From a1d7c51d27734f5af98e96d26a50357d6e145009 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Tue, 24 Aug 2021 20:42:32 +0300
Subject: [PATCH 01/10] ty::layout: move `trait FnAbiExt` to just before its
 `impl`.

---
 compiler/rustc_middle/src/ty/layout.rs | 56 +++++++++++++-------------
 1 file changed, 28 insertions(+), 28 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 1bea1cbc3b94b..83bb6b15262fd 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2633,34 +2633,6 @@ impl<'tcx> ty::Instance<'tcx> {
     }
 }
 
-pub trait FnAbiExt<'tcx, C>
-where
-    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
-{
-    /// Compute a `FnAbi` suitable for indirect calls, i.e. to `fn` pointers.
-    ///
-    /// NB: this doesn't handle virtual calls - those should use `FnAbi::of_instance`
-    /// instead, where the instance is an `InstanceDef::Virtual`.
-    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
-
-    /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for
-    /// direct calls to an `fn`.
-    ///
-    /// NB: that includes virtual calls, which are represented by "direct calls"
-    /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`).
-    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
-
-    fn new_internal(
-        cx: &C,
-        sig: ty::PolyFnSig<'tcx>,
-        extra_args: &[Ty<'tcx>],
-        caller_location: Option<Ty<'tcx>>,
-        codegen_fn_attr_flags: CodegenFnAttrFlags,
-        make_self_ptr_thin: bool,
-    ) -> Self;
-    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
-}
-
 /// Calculates whether a function's ABI can unwind or not.
 ///
 /// This takes two primary parameters:
@@ -2816,6 +2788,34 @@ pub fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
     }
 }
 
+pub trait FnAbiExt<'tcx, C>
+where
+    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+{
+    /// Compute a `FnAbi` suitable for indirect calls, i.e. to `fn` pointers.
+    ///
+    /// NB: this doesn't handle virtual calls - those should use `FnAbi::of_instance`
+    /// instead, where the instance is an `InstanceDef::Virtual`.
+    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
+
+    /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for
+    /// direct calls to an `fn`.
+    ///
+    /// NB: that includes virtual calls, which are represented by "direct calls"
+    /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`).
+    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
+
+    fn new_internal(
+        cx: &C,
+        sig: ty::PolyFnSig<'tcx>,
+        extra_args: &[Ty<'tcx>],
+        caller_location: Option<Ty<'tcx>>,
+        codegen_fn_attr_flags: CodegenFnAttrFlags,
+        make_self_ptr_thin: bool,
+    ) -> Self;
+    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
+}
+
 impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
 where
     C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,

From feca7d0a03ffe1c786f6fe00330b6d2df59bcfef Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Tue, 24 Aug 2021 20:45:37 +0300
Subject: [PATCH 02/10] ty::layout: split out a private trait from `FnAbiExt`.

---
 compiler/rustc_middle/src/ty/layout.rs | 31 +++++++++++++++++---------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 83bb6b15262fd..793dda5c928bc 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2804,16 +2804,6 @@ where
     /// NB: that includes virtual calls, which are represented by "direct calls"
     /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`).
     fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
-
-    fn new_internal(
-        cx: &C,
-        sig: ty::PolyFnSig<'tcx>,
-        extra_args: &[Ty<'tcx>],
-        caller_location: Option<Ty<'tcx>>,
-        codegen_fn_attr_flags: CodegenFnAttrFlags,
-        make_self_ptr_thin: bool,
-    ) -> Self;
-    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
 }
 
 impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
@@ -2844,7 +2834,28 @@ where
             matches!(instance.def, ty::InstanceDef::Virtual(..)),
         )
     }
+}
+
+/// Implementation detail of computing `FnAbi`s, shouldn't be exported.
+trait FnAbiInternalExt<'tcx, C>
+where
+    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+{
+    fn new_internal(
+        cx: &C,
+        sig: ty::PolyFnSig<'tcx>,
+        extra_args: &[Ty<'tcx>],
+        caller_location: Option<Ty<'tcx>>,
+        codegen_fn_attr_flags: CodegenFnAttrFlags,
+        make_self_ptr_thin: bool,
+    ) -> Self;
+    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
+}
 
+impl<'tcx, C> FnAbiInternalExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
+where
+    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+{
     fn new_internal(
         cx: &C,
         sig: ty::PolyFnSig<'tcx>,

From 4d36faf9ef10bda32c606517d0f2007fd53b16ac Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Wed, 25 Aug 2021 11:50:26 +0300
Subject: [PATCH 03/10] rustc_target: `adjust_for_cabi` ->
 `adjust_for_foreign_abi`.

---
 compiler/rustc_middle/src/ty/layout.rs    | 2 +-
 compiler/rustc_target/src/abi/call/mod.rs | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 793dda5c928bc..95dda620cd445 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -3098,7 +3098,7 @@ where
             return;
         }
 
-        if let Err(msg) = self.adjust_for_cabi(cx, abi) {
+        if let Err(msg) = self.adjust_for_foreign_abi(cx, abi) {
             cx.tcx().sess.fatal(&msg);
         }
     }
diff --git a/compiler/rustc_target/src/abi/call/mod.rs b/compiler/rustc_target/src/abi/call/mod.rs
index 927bebd8157a6..bce86ca809d2a 100644
--- a/compiler/rustc_target/src/abi/call/mod.rs
+++ b/compiler/rustc_target/src/abi/call/mod.rs
@@ -600,7 +600,7 @@ pub struct FnAbi<'a, Ty> {
 }
 
 impl<'a, Ty> FnAbi<'a, Ty> {
-    pub fn adjust_for_cabi<C>(&mut self, cx: &C, abi: spec::abi::Abi) -> Result<(), String>
+    pub fn adjust_for_foreign_abi<C>(&mut self, cx: &C, abi: spec::abi::Abi) -> Result<(), String>
     where
         Ty: TyAbiInterface<'a, C> + Copy,
         C: HasDataLayout + HasTargetSpec,

From 7f2f927eb81c75fd0f8e5900588eb962be0a4be9 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Thu, 26 Aug 2021 19:01:55 +0300
Subject: [PATCH 04/10] ty::layout: propagate errors up to (but not out of)
 `FnAbi::of_*`.

---
 compiler/rustc_middle/src/ty/layout.rs    | 129 +++++++++++++++++-----
 compiler/rustc_target/src/abi/call/mod.rs |  27 ++++-
 2 files changed, 129 insertions(+), 27 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 95dda620cd445..e11993c758099 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -18,7 +18,7 @@ use rustc_target::abi::call::{
     ArgAbi, ArgAttribute, ArgAttributes, ArgExtension, Conv, FnAbi, PassMode, Reg, RegKind,
 };
 use rustc_target::abi::*;
-use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy};
+use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy, Target};
 
 use std::cmp;
 use std::fmt;
@@ -2015,6 +2015,12 @@ impl<'tcx> HasDataLayout for TyCtxt<'tcx> {
     }
 }
 
+impl<'tcx> HasTargetSpec for TyCtxt<'tcx> {
+    fn target_spec(&self) -> &Target {
+        &self.sess.target
+    }
+}
+
 impl<'tcx> HasTyCtxt<'tcx> for TyCtxt<'tcx> {
     #[inline]
     fn tcx(&self) -> TyCtxt<'tcx> {
@@ -2048,6 +2054,12 @@ impl<'tcx, T: HasDataLayout> HasDataLayout for LayoutCx<'tcx, T> {
     }
 }
 
+impl<'tcx, T: HasTargetSpec> HasTargetSpec for LayoutCx<'tcx, T> {
+    fn target_spec(&self) -> &Target {
+        self.tcx.target_spec()
+    }
+}
+
 impl<'tcx, T: HasTyCtxt<'tcx>> HasTyCtxt<'tcx> for LayoutCx<'tcx, T> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx.tcx()
@@ -2788,9 +2800,39 @@ pub fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
     }
 }
 
+/// Error produced by attempting to compute or adjust a `FnAbi`.
+enum FnAbiError<'tcx> {
+    /// Error produced by a `layout_of` call, while computing `FnAbi` initially.
+    Layout(LayoutError<'tcx>),
+
+    /// Error produced by attempting to adjust a `FnAbi`, for a "foreign" ABI.
+    AdjustForForeignAbi(call::AdjustForForeignAbiError),
+}
+
+impl From<LayoutError<'tcx>> for FnAbiError<'tcx> {
+    fn from(err: LayoutError<'tcx>) -> Self {
+        Self::Layout(err)
+    }
+}
+
+impl From<call::AdjustForForeignAbiError> for FnAbiError<'_> {
+    fn from(err: call::AdjustForForeignAbiError) -> Self {
+        Self::AdjustForForeignAbi(err)
+    }
+}
+
+impl<'tcx> fmt::Display for FnAbiError<'tcx> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Layout(err) => err.fmt(f),
+            Self::AdjustForForeignAbi(err) => err.fmt(f),
+        }
+    }
+}
+
 pub trait FnAbiExt<'tcx, C>
 where
-    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+    C: HasTyCtxt<'tcx> + HasParamEnv<'tcx>,
 {
     /// Compute a `FnAbi` suitable for indirect calls, i.e. to `fn` pointers.
     ///
@@ -2808,10 +2850,26 @@ where
 
 impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
 where
-    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+    C: HasTyCtxt<'tcx> + HasParamEnv<'tcx>,
 {
     fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
-        call::FnAbi::new_internal(cx, sig, extra_args, None, CodegenFnAttrFlags::empty(), false)
+        call::FnAbi::new_internal(
+            &LayoutCx { tcx: cx.tcx(), param_env: cx.param_env() },
+            sig,
+            extra_args,
+            None,
+            CodegenFnAttrFlags::empty(),
+            false,
+        )
+        .unwrap_or_else(|err| {
+            // FIXME(eddyb) get a better `span` here.
+            let span = DUMMY_SP;
+            if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+                cx.tcx().sess.span_fatal(span, &err.to_string())
+            } else {
+                span_bug!(span, "`FnAbi::of_fn_ptr({}, {:?})` failed: {}", sig, extra_args, err);
+            }
+        })
     }
 
     fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
@@ -2826,35 +2884,57 @@ where
         let attrs = cx.tcx().codegen_fn_attrs(instance.def_id()).flags;
 
         call::FnAbi::new_internal(
-            cx,
+            &LayoutCx { tcx: cx.tcx(), param_env: cx.param_env() },
             sig,
             extra_args,
             caller_location,
             attrs,
             matches!(instance.def, ty::InstanceDef::Virtual(..)),
         )
+        .unwrap_or_else(|err| {
+            // FIXME(eddyb) get a better `span` here.
+            let span = cx.tcx().def_span(instance.def_id());
+            if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+                cx.tcx().sess.span_fatal(span, &err.to_string())
+            } else {
+                span_bug!(
+                    span,
+                    "`FnAbi::of_instance({}, {:?})` failed: {}",
+                    instance,
+                    extra_args,
+                    err
+                );
+            }
+        })
     }
 }
 
 /// Implementation detail of computing `FnAbi`s, shouldn't be exported.
-trait FnAbiInternalExt<'tcx, C>
+// FIXME(eddyb) move this off of being generic on `C: LayoutOf`, and
+// explicitly take `LayoutCx` *or* `TyCtxt` and `ParamEnvAnd<...>`.
+trait FnAbiInternalExt<'tcx, C>: Sized
 where
-    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+    C: LayoutOf<'tcx, LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>>
+        + HasTargetSpec,
 {
+    // FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
+    // arguments of this method, into a separate `struct`.
     fn new_internal(
         cx: &C,
         sig: ty::PolyFnSig<'tcx>,
         extra_args: &[Ty<'tcx>],
         caller_location: Option<Ty<'tcx>>,
         codegen_fn_attr_flags: CodegenFnAttrFlags,
+        // FIXME(eddyb) replace this with something typed, like an `enum`.
         make_self_ptr_thin: bool,
-    ) -> Self;
-    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi);
+    ) -> Result<Self, FnAbiError<'tcx>>;
+    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) -> Result<(), FnAbiError<'tcx>>;
 }
 
 impl<'tcx, C> FnAbiInternalExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
 where
-    C: LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>> + HasTargetSpec,
+    C: LayoutOf<'tcx, LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>>
+        + HasTargetSpec,
 {
     fn new_internal(
         cx: &C,
@@ -2863,10 +2943,10 @@ where
         caller_location: Option<Ty<'tcx>>,
         codegen_fn_attr_flags: CodegenFnAttrFlags,
         force_thin_self_ptr: bool,
-    ) -> Self {
+    ) -> Result<Self, FnAbiError<'tcx>> {
         debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args);
 
-        let sig = cx.tcx().normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig);
+        let sig = cx.tcx().normalize_erasing_late_bound_regions(cx.param_env(), sig);
 
         let conv = conv_from_spec_abi(cx.tcx(), sig.abi);
 
@@ -2972,10 +3052,10 @@ where
             }
         };
 
-        let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| {
+        let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
             let is_return = arg_idx.is_none();
 
-            let layout = cx.layout_of(ty);
+            let layout = cx.layout_of(ty)?;
             let layout = if force_thin_self_ptr && arg_idx == Some(0) {
                 // Don't pass the vtable, it's not an argument of the virtual fn.
                 // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
@@ -3006,11 +3086,11 @@ where
                 }
             }
 
-            arg
+            Ok(arg)
         };
 
         let mut fn_abi = FnAbi {
-            ret: arg_of(sig.output(), None),
+            ret: arg_of(sig.output(), None)?,
             args: inputs
                 .iter()
                 .cloned()
@@ -3018,20 +3098,20 @@ where
                 .chain(caller_location)
                 .enumerate()
                 .map(|(i, ty)| arg_of(ty, Some(i)))
-                .collect(),
+                .collect::<Result<_, _>>()?,
             c_variadic: sig.c_variadic,
             fixed_count: inputs.len(),
             conv,
             can_unwind: fn_can_unwind(cx.tcx(), codegen_fn_attr_flags, sig.abi),
         };
-        fn_abi.adjust_for_abi(cx, sig.abi);
+        fn_abi.adjust_for_abi(cx, sig.abi)?;
         debug!("FnAbi::new_internal = {:?}", fn_abi);
-        fn_abi
+        Ok(fn_abi)
     }
 
-    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) {
+    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) -> Result<(), FnAbiError<'tcx>> {
         if abi == SpecAbi::Unadjusted {
-            return;
+            return Ok(());
         }
 
         if abi == SpecAbi::Rust
@@ -3095,12 +3175,11 @@ where
             for arg in &mut self.args {
                 fixup(arg);
             }
-            return;
+        } else {
+            self.adjust_for_foreign_abi(cx, abi)?;
         }
 
-        if let Err(msg) = self.adjust_for_foreign_abi(cx, abi) {
-            cx.tcx().sess.fatal(&msg);
-        }
+        Ok(())
     }
 }
 
diff --git a/compiler/rustc_target/src/abi/call/mod.rs b/compiler/rustc_target/src/abi/call/mod.rs
index bce86ca809d2a..75c526c97414f 100644
--- a/compiler/rustc_target/src/abi/call/mod.rs
+++ b/compiler/rustc_target/src/abi/call/mod.rs
@@ -1,6 +1,7 @@
 use crate::abi::{self, Abi, Align, FieldsShape, Size};
 use crate::abi::{HasDataLayout, TyAbiInterface, TyAndLayout};
 use crate::spec::{self, HasTargetSpec};
+use std::fmt;
 
 mod aarch64;
 mod amdgpu;
@@ -599,8 +600,28 @@ pub struct FnAbi<'a, Ty> {
     pub can_unwind: bool,
 }
 
+/// Error produced by attempting to adjust a `FnAbi`, for a "foreign" ABI.
+pub enum AdjustForForeignAbiError {
+    /// Target architecture doesn't support "foreign" (i.e. non-Rust) ABIs.
+    Unsupported { arch: String, abi: spec::abi::Abi },
+}
+
+impl fmt::Display for AdjustForForeignAbiError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Unsupported { arch, abi } => {
+                write!(f, "target architecture {:?} does not support `extern {}` ABI", arch, abi)
+            }
+        }
+    }
+}
+
 impl<'a, Ty> FnAbi<'a, Ty> {
-    pub fn adjust_for_foreign_abi<C>(&mut self, cx: &C, abi: spec::abi::Abi) -> Result<(), String>
+    pub fn adjust_for_foreign_abi<C>(
+        &mut self,
+        cx: &C,
+        abi: spec::abi::Abi,
+    ) -> Result<(), AdjustForForeignAbiError>
     where
         Ty: TyAbiInterface<'a, C> + Copy,
         C: HasDataLayout + HasTargetSpec,
@@ -655,7 +676,9 @@ impl<'a, Ty> FnAbi<'a, Ty> {
             }
             "asmjs" => wasm::compute_c_abi_info(cx, self),
             "bpf" => bpf::compute_abi_info(self),
-            a => return Err(format!("unrecognized arch \"{}\" in target specification", a)),
+            arch => {
+                return Err(AdjustForForeignAbiError::Unsupported { arch: arch.to_string(), abi });
+            }
         }
 
         Ok(())

From 0c02e3f550dbebe297f897b03be4e9dd3454695e Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Thu, 26 Aug 2021 19:47:07 +0300
Subject: [PATCH 05/10] ty::context: move interning `Allocation`s and `Layout`s
 to `direct_interners!`.

---
 compiler/rustc_middle/src/ty/context.rs | 81 ++++++++-----------------
 1 file changed, 26 insertions(+), 55 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 1f5057d1da22f..7cd5584c3589b 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -118,8 +118,8 @@ pub struct CtxtInterners<'tcx> {
     /// The arena that types, regions, etc. are allocated from.
     arena: &'tcx WorkerLocal<Arena<'tcx>>,
 
-    /// Specifically use a speedy hash algorithm for these hash sets, since
-    /// they're accessed quite often.
+    // Specifically use a speedy hash algorithm for these hash sets, since
+    // they're accessed quite often.
     type_: InternedSet<'tcx, TyS<'tcx>>,
     type_list: InternedSet<'tcx, List<Ty<'tcx>>>,
     substs: InternedSet<'tcx, InternalSubsts<'tcx>>,
@@ -132,9 +132,9 @@ pub struct CtxtInterners<'tcx> {
     projs: InternedSet<'tcx, List<ProjectionKind>>,
     place_elems: InternedSet<'tcx, List<PlaceElem<'tcx>>>,
     const_: InternedSet<'tcx, Const<'tcx>>,
-    /// Const allocations.
-    allocation: InternedSet<'tcx, Allocation>,
+    const_allocation: InternedSet<'tcx, Allocation>,
     bound_variable_kinds: InternedSet<'tcx, List<ty::BoundVariableKind>>,
+    layout: InternedSet<'tcx, Layout>,
 }
 
 impl<'tcx> CtxtInterners<'tcx> {
@@ -152,8 +152,9 @@ impl<'tcx> CtxtInterners<'tcx> {
             projs: Default::default(),
             place_elems: Default::default(),
             const_: Default::default(),
-            allocation: Default::default(),
+            const_allocation: Default::default(),
             bound_variable_kinds: Default::default(),
+            layout: Default::default(),
         }
     }
 
@@ -1062,10 +1063,9 @@ pub struct GlobalCtxt<'tcx> {
     /// Stores memory for globals (statics/consts).
     pub(crate) alloc_map: Lock<interpret::AllocMap<'tcx>>,
 
-    layout_interner: ShardedHashMap<&'tcx Layout, ()>,
-
     output_filenames: Arc<OutputFilenames>,
 
+    // FIXME(eddyb) this doesn't belong here and should be using a query.
     pub(super) vtables_cache:
         Lock<FxHashMap<(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>), AllocId>>,
 }
@@ -1107,13 +1107,6 @@ impl<'tcx> TyCtxt<'tcx> {
         self.arena.alloc(ty::AdtDef::new(self, did, kind, variants, repr))
     }
 
-    pub fn intern_const_alloc(self, alloc: Allocation) -> &'tcx Allocation {
-        self.interners
-            .allocation
-            .intern(alloc, |alloc| Interned(self.interners.arena.alloc(alloc)))
-            .0
-    }
-
     /// Allocates a read-only byte or string literal for `mir::interpret`.
     pub fn allocate_bytes(self, bytes: &[u8]) -> interpret::AllocId {
         // Create an allocation that just contains these bytes.
@@ -1122,20 +1115,19 @@ impl<'tcx> TyCtxt<'tcx> {
         self.create_memory_alloc(alloc)
     }
 
+    // FIXME(eddyb) move to `direct_interners!`.
     pub fn intern_stability(self, stab: attr::Stability) -> &'tcx attr::Stability {
         self.stability_interner.intern(stab, |stab| self.arena.alloc(stab))
     }
 
+    // FIXME(eddyb) move to `direct_interners!`.
     pub fn intern_const_stability(self, stab: attr::ConstStability) -> &'tcx attr::ConstStability {
         self.const_stability_interner.intern(stab, |stab| self.arena.alloc(stab))
     }
 
-    pub fn intern_layout(self, layout: Layout) -> &'tcx Layout {
-        self.layout_interner.intern(layout, |layout| self.arena.alloc(layout))
-    }
-
     /// Returns a range of the start/end indices specified with the
     /// `rustc_layout_scalar_valid_range` attribute.
+    // FIXME(eddyb) this is an awkward spot for this method, maybe move it?
     pub fn layout_scalar_valid_range(self, def_id: DefId) -> (Bound<u128>, Bound<u128>) {
         let attrs = self.get_attrs(def_id);
         let get = |name| {
@@ -1210,7 +1202,6 @@ impl<'tcx> TyCtxt<'tcx> {
             evaluation_cache: Default::default(),
             crate_name: Symbol::intern(crate_name),
             data_layout,
-            layout_interner: Default::default(),
             stability_interner: Default::default(),
             const_stability_interner: Default::default(),
             alloc_map: Lock::new(interpret::AllocMap::new()),
@@ -1670,7 +1661,7 @@ macro_rules! nop_list_lift {
 nop_lift! {type_; Ty<'a> => Ty<'tcx>}
 nop_lift! {region; Region<'a> => Region<'tcx>}
 nop_lift! {const_; &'a Const<'a> => &'tcx Const<'tcx>}
-nop_lift! {allocation; &'a Allocation => &'tcx Allocation}
+nop_lift! {const_allocation; &'a Allocation => &'tcx Allocation}
 nop_lift! {predicate; &'a PredicateInner<'a> => &'tcx PredicateInner<'tcx>}
 
 nop_list_lift! {type_list; Ty<'a> => Ty<'tcx>}
@@ -1962,8 +1953,12 @@ impl<'tcx> TyCtxt<'tcx> {
                     "Const Stability interner: #{}",
                     self.0.const_stability_interner.len()
                 )?;
-                writeln!(fmt, "Allocation interner: #{}", self.0.interners.allocation.len())?;
-                writeln!(fmt, "Layout interner: #{}", self.0.layout_interner.len())?;
+                writeln!(
+                    fmt,
+                    "Const Allocation interner: #{}",
+                    self.0.interners.const_allocation.len()
+                )?;
+                writeln!(fmt, "Layout interner: #{}", self.0.interners.layout.len())?;
 
                 Ok(())
             }
@@ -2051,38 +2046,6 @@ impl<'tcx, T> Borrow<[T]> for Interned<'tcx, List<T>> {
     }
 }
 
-impl<'tcx> Borrow<RegionKind> for Interned<'tcx, RegionKind> {
-    fn borrow(&self) -> &RegionKind {
-        &self.0
-    }
-}
-
-impl<'tcx> Borrow<Const<'tcx>> for Interned<'tcx, Const<'tcx>> {
-    fn borrow<'a>(&'a self) -> &'a Const<'tcx> {
-        &self.0
-    }
-}
-
-impl<'tcx> Borrow<Allocation> for Interned<'tcx, Allocation> {
-    fn borrow<'a>(&'a self) -> &'a Allocation {
-        &self.0
-    }
-}
-
-impl<'tcx> PartialEq for Interned<'tcx, Allocation> {
-    fn eq(&self, other: &Self) -> bool {
-        self.0 == other.0
-    }
-}
-
-impl<'tcx> Eq for Interned<'tcx, Allocation> {}
-
-impl<'tcx> Hash for Interned<'tcx, Allocation> {
-    fn hash<H: Hasher>(&self, s: &mut H) {
-        self.0.hash(s)
-    }
-}
-
 macro_rules! direct_interners {
     ($($name:ident: $method:ident($ty:ty),)+) => {
         $(impl<'tcx> PartialEq for Interned<'tcx, $ty> {
@@ -2099,9 +2062,15 @@ macro_rules! direct_interners {
             }
         }
 
+        impl<'tcx> Borrow<$ty> for Interned<'tcx, $ty> {
+            fn borrow<'a>(&'a self) -> &'a $ty {
+                &self.0
+            }
+        }
+
         impl<'tcx> TyCtxt<'tcx> {
             pub fn $method(self, v: $ty) -> &'tcx $ty {
-                self.interners.$name.intern_ref(&v, || {
+                self.interners.$name.intern(v, |v| {
                     Interned(self.interners.arena.alloc(v))
                 }).0
             }
@@ -2112,6 +2081,8 @@ macro_rules! direct_interners {
 direct_interners! {
     region: mk_region(RegionKind),
     const_: mk_const(Const<'tcx>),
+    const_allocation: intern_const_alloc(Allocation),
+    layout: intern_layout(Layout),
 }
 
 macro_rules! slice_interners {

From 344df76fed727b565b905f3f32ee467f8e3aec2d Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Thu, 26 Aug 2021 21:58:34 +0300
Subject: [PATCH 06/10] ty::layout: intern `FnAbi`s as `&'tcx`.

---
 .../rustc_codegen_cranelift/src/common.rs     |  2 +-
 compiler/rustc_codegen_ssa/src/mir/block.rs   |  2 +-
 compiler/rustc_codegen_ssa/src/mir/mod.rs     |  2 +-
 compiler/rustc_middle/src/arena.rs            |  3 ++-
 compiler/rustc_middle/src/ty/context.rs       |  5 +++++
 compiler/rustc_middle/src/ty/layout.rs        | 16 +++++++-------
 compiler/rustc_target/src/abi/call/mod.rs     | 22 +++++++++----------
 7 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/src/common.rs b/compiler/rustc_codegen_cranelift/src/common.rs
index 6f7ca51d038c0..06d1fc717cc92 100644
--- a/compiler/rustc_codegen_cranelift/src/common.rs
+++ b/compiler/rustc_codegen_cranelift/src/common.rs
@@ -239,7 +239,7 @@ pub(crate) struct FunctionCx<'m, 'clif, 'tcx: 'm> {
     pub(crate) instance: Instance<'tcx>,
     pub(crate) symbol_name: SymbolName<'tcx>,
     pub(crate) mir: &'tcx Body<'tcx>,
-    pub(crate) fn_abi: Option<FnAbi<'tcx, Ty<'tcx>>>,
+    pub(crate) fn_abi: Option<&'tcx FnAbi<'tcx, Ty<'tcx>>>,
 
     pub(crate) bcx: FunctionBuilder<'clif>,
     pub(crate) block_map: IndexVec<BasicBlock, Block>,
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index cd0e9354c2441..c557946afbc4b 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -124,7 +124,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
         &self,
         fx: &mut FunctionCx<'a, 'tcx, Bx>,
         bx: &mut Bx,
-        fn_abi: FnAbi<'tcx, Ty<'tcx>>,
+        fn_abi: &'tcx FnAbi<'tcx, Ty<'tcx>>,
         fn_ptr: Bx::Value,
         llargs: &[Bx::Value],
         destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index e2edd44826717..2c7636f1913dd 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -29,7 +29,7 @@ pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
 
     cx: &'a Bx::CodegenCx,
 
-    fn_abi: FnAbi<'tcx, Ty<'tcx>>,
+    fn_abi: &'tcx FnAbi<'tcx, Ty<'tcx>>,
 
     /// When unwinding is initiated, we have to store this personality
     /// value somewhere so that we can load it and re-use it in the
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index 59db2c6636ff9..2dd43a4e8522d 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -11,7 +11,8 @@
 macro_rules! arena_types {
     ($macro:path, $tcx:lifetime) => (
         $macro!([
-            [] layouts: rustc_target::abi::Layout,
+            [] layout: rustc_target::abi::Layout,
+            [] fn_abi: rustc_target::abi::call::FnAbi<$tcx, rustc_middle::ty::Ty<$tcx>>,
             // AdtDef are interned and compared by address
             [] adt_def: rustc_middle::ty::AdtDef,
             [] steal_thir: rustc_data_structures::steal::Steal<rustc_middle::thir::Thir<$tcx>>,
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 7cd5584c3589b..e803a667879a1 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -55,6 +55,7 @@ use rustc_span::def_id::{DefPathHash, StableCrateId};
 use rustc_span::source_map::{MultiSpan, SourceMap};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
+use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::{Layout, TargetDataLayout, VariantIdx};
 use rustc_target::spec::abi;
 
@@ -135,6 +136,7 @@ pub struct CtxtInterners<'tcx> {
     const_allocation: InternedSet<'tcx, Allocation>,
     bound_variable_kinds: InternedSet<'tcx, List<ty::BoundVariableKind>>,
     layout: InternedSet<'tcx, Layout>,
+    fn_abi: InternedSet<'tcx, FnAbi<'tcx, Ty<'tcx>>>,
 }
 
 impl<'tcx> CtxtInterners<'tcx> {
@@ -155,6 +157,7 @@ impl<'tcx> CtxtInterners<'tcx> {
             const_allocation: Default::default(),
             bound_variable_kinds: Default::default(),
             layout: Default::default(),
+            fn_abi: Default::default(),
         }
     }
 
@@ -1959,6 +1962,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     self.0.interners.const_allocation.len()
                 )?;
                 writeln!(fmt, "Layout interner: #{}", self.0.interners.layout.len())?;
+                writeln!(fmt, "FnAbi interner: #{}", self.0.interners.fn_abi.len())?;
 
                 Ok(())
             }
@@ -2083,6 +2087,7 @@ direct_interners! {
     const_: mk_const(Const<'tcx>),
     const_allocation: intern_const_alloc(Allocation),
     layout: intern_layout(Layout),
+    fn_abi: intern_fn_abi(FnAbi<'tcx, Ty<'tcx>>),
 }
 
 macro_rules! slice_interners {
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index e11993c758099..42ac77054190a 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2838,21 +2838,21 @@ where
     ///
     /// NB: this doesn't handle virtual calls - those should use `FnAbi::of_instance`
     /// instead, where the instance is an `InstanceDef::Virtual`.
-    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
+    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self;
 
     /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for
     /// direct calls to an `fn`.
     ///
     /// NB: that includes virtual calls, which are represented by "direct calls"
     /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`).
-    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self;
+    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self;
 }
 
 impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
 where
     C: HasTyCtxt<'tcx> + HasParamEnv<'tcx>,
 {
-    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
+    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self {
         call::FnAbi::new_internal(
             &LayoutCx { tcx: cx.tcx(), param_env: cx.param_env() },
             sig,
@@ -2872,7 +2872,7 @@ where
         })
     }
 
-    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> Self {
+    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self {
         let sig = instance.fn_sig_for_fn_abi(cx.tcx());
 
         let caller_location = if instance.def.requires_caller_location(cx.tcx()) {
@@ -2912,7 +2912,7 @@ where
 /// Implementation detail of computing `FnAbi`s, shouldn't be exported.
 // FIXME(eddyb) move this off of being generic on `C: LayoutOf`, and
 // explicitly take `LayoutCx` *or* `TyCtxt` and `ParamEnvAnd<...>`.
-trait FnAbiInternalExt<'tcx, C>: Sized
+trait FnAbiInternalExt<'tcx, C>
 where
     C: LayoutOf<'tcx, LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>>
         + HasTargetSpec,
@@ -2927,7 +2927,7 @@ where
         codegen_fn_attr_flags: CodegenFnAttrFlags,
         // FIXME(eddyb) replace this with something typed, like an `enum`.
         make_self_ptr_thin: bool,
-    ) -> Result<Self, FnAbiError<'tcx>>;
+    ) -> Result<&'tcx Self, FnAbiError<'tcx>>;
     fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) -> Result<(), FnAbiError<'tcx>>;
 }
 
@@ -2943,7 +2943,7 @@ where
         caller_location: Option<Ty<'tcx>>,
         codegen_fn_attr_flags: CodegenFnAttrFlags,
         force_thin_self_ptr: bool,
-    ) -> Result<Self, FnAbiError<'tcx>> {
+    ) -> Result<&'tcx Self, FnAbiError<'tcx>> {
         debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args);
 
         let sig = cx.tcx().normalize_erasing_late_bound_regions(cx.param_env(), sig);
@@ -3106,7 +3106,7 @@ where
         };
         fn_abi.adjust_for_abi(cx, sig.abi)?;
         debug!("FnAbi::new_internal = {:?}", fn_abi);
-        Ok(fn_abi)
+        Ok(cx.tcx().intern_fn_abi(fn_abi))
     }
 
     fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) -> Result<(), FnAbiError<'tcx>> {
diff --git a/compiler/rustc_target/src/abi/call/mod.rs b/compiler/rustc_target/src/abi/call/mod.rs
index 75c526c97414f..6f06f2b56ada6 100644
--- a/compiler/rustc_target/src/abi/call/mod.rs
+++ b/compiler/rustc_target/src/abi/call/mod.rs
@@ -25,7 +25,7 @@ mod x86;
 mod x86_64;
 mod x86_win64;
 
-#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub enum PassMode {
     /// Ignore the argument.
     ///
@@ -60,7 +60,7 @@ pub use attr_impl::ArgAttribute;
 mod attr_impl {
     // The subset of llvm::Attribute needed for arguments, packed into a bitfield.
     bitflags::bitflags! {
-        #[derive(Default)]
+        #[derive(Default, HashStable_Generic)]
         pub struct ArgAttribute: u16 {
             const NoAlias   = 1 << 1;
             const NoCapture = 1 << 2;
@@ -77,7 +77,7 @@ mod attr_impl {
 /// Sometimes an ABI requires small integers to be extended to a full or partial register. This enum
 /// defines if this extension should be zero-extension or sign-extension when necessary. When it is
 /// not necessary to extend the argument, this enum is ignored.
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub enum ArgExtension {
     None,
     Zext,
@@ -86,7 +86,7 @@ pub enum ArgExtension {
 
 /// A compact representation of LLVM attributes (at least those relevant for this module)
 /// that can be manipulated without interacting with LLVM's Attribute machinery.
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct ArgAttributes {
     pub regular: ArgAttribute,
     pub arg_ext: ArgExtension,
@@ -127,14 +127,14 @@ impl ArgAttributes {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub enum RegKind {
     Integer,
     Float,
     Vector,
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct Reg {
     pub kind: RegKind,
     pub size: Size,
@@ -184,7 +184,7 @@ impl Reg {
 
 /// An argument passed entirely registers with the
 /// same kind (e.g., HFA / HVA on PPC64 and AArch64).
-#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct Uniform {
     pub unit: Reg,
 
@@ -209,7 +209,7 @@ impl Uniform {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct CastTarget {
     pub prefix: [Option<RegKind>; 8],
     pub prefix_chunk_size: Size,
@@ -437,7 +437,7 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
 
 /// Information about how to pass an argument to,
 /// or return a value from, a function, under some ABI.
-#[derive(Debug)]
+#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct ArgAbi<'a, Ty> {
     pub layout: TyAndLayout<'a, Ty>,
 
@@ -545,7 +545,7 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub enum Conv {
     // General language calling conventions, for which every target
     // should have its own backend (e.g. LLVM) support.
@@ -579,7 +579,7 @@ pub enum Conv {
 ///
 /// I will do my best to describe this structure, but these
 /// comments are reverse-engineered and may be inaccurate. -NDM
-#[derive(Debug)]
+#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
 pub struct FnAbi<'a, Ty> {
     /// The LLVM types of each argument.
     pub args: Vec<ArgAbi<'a, Ty>>,

From 319dec89e7cee269a4a9b029a2da846bb76ea813 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Wed, 1 Sep 2021 14:19:49 +0300
Subject: [PATCH 07/10] rustc_codegen_llvm: move misplaced `HasParamEnv` impl.

---
 compiler/rustc_codegen_llvm/src/context.rs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 2d397dc583534..1d6efdf5f2510 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -835,6 +835,12 @@ impl ty::layout::HasTyCtxt<'tcx> for CodegenCx<'ll, 'tcx> {
     }
 }
 
+impl<'tcx, 'll> HasParamEnv<'tcx> for CodegenCx<'ll, 'tcx> {
+    fn param_env(&self) -> ty::ParamEnv<'tcx> {
+        ty::ParamEnv::reveal_all()
+    }
+}
+
 impl LayoutOfHelpers<'tcx> for CodegenCx<'ll, 'tcx> {
     type LayoutOfResult = TyAndLayout<'tcx>;
 
@@ -847,9 +853,3 @@ impl LayoutOfHelpers<'tcx> for CodegenCx<'ll, 'tcx> {
         }
     }
 }
-
-impl<'tcx, 'll> HasParamEnv<'tcx> for CodegenCx<'ll, 'tcx> {
-    fn param_env(&self) -> ty::ParamEnv<'tcx> {
-        ty::ParamEnv::reveal_all()
-    }
-}

From e9b68304efc447a7bcd35b06511f6dfdfe9da16d Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Thu, 2 Sep 2021 00:09:34 +0300
Subject: [PATCH 08/10] ty::layout: replicate `layout_of` setup for
 `fn_abi_of_{fn_ptr,instance}`.

---
 .../rustc_codegen_cranelift/src/abi/mod.rs    |  12 +-
 compiler/rustc_codegen_cranelift/src/base.rs  |   5 +-
 .../rustc_codegen_cranelift/src/common.rs     |  55 ++++-
 .../rustc_codegen_cranelift/src/constant.rs   |   4 +-
 .../src/pretty_clif.rs                        |   5 +-
 compiler/rustc_codegen_llvm/src/builder.rs    |  20 +-
 compiler/rustc_codegen_llvm/src/callee.rs     |   6 +-
 compiler/rustc_codegen_llvm/src/context.rs    |  46 +++-
 .../src/coverageinfo/mod.rs                   |   7 +-
 .../src/debuginfo/create_scope_map.rs         |   5 +-
 compiler/rustc_codegen_llvm/src/intrinsic.rs  |   4 +-
 compiler/rustc_codegen_llvm/src/mono_item.rs  |   5 +-
 compiler/rustc_codegen_llvm/src/type_of.rs    |   5 +-
 compiler/rustc_codegen_ssa/src/mir/block.rs   |  14 +-
 compiler/rustc_codegen_ssa/src/mir/mod.rs     |   4 +-
 .../rustc_codegen_ssa/src/traits/backend.rs   |  16 +-
 compiler/rustc_middle/src/ty/layout.rs        | 221 +++++++++---------
 17 files changed, 277 insertions(+), 157 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/src/abi/mod.rs b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
index 13790409e59f6..6317e1d5d1aba 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
@@ -5,7 +5,7 @@ mod pass_mode;
 mod returning;
 
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use rustc_middle::ty::layout::FnAbiExt;
+use rustc_middle::ty::layout::FnAbiOf;
 use rustc_target::abi::call::{Conv, FnAbi};
 use rustc_target::spec::abi::Abi;
 
@@ -53,7 +53,7 @@ pub(crate) fn get_function_sig<'tcx>(
     inst: Instance<'tcx>,
 ) -> Signature {
     assert!(!inst.substs.needs_infer());
-    clif_sig_from_fn_abi(tcx, triple, &FnAbi::of_instance(&RevealAllLayoutCx(tcx), inst, &[]))
+    clif_sig_from_fn_abi(tcx, triple, &RevealAllLayoutCx(tcx).fn_abi_of_instance(inst, &[]))
 }
 
 /// Instance must be monomorphized
@@ -355,9 +355,9 @@ pub(crate) fn codegen_terminator_call<'tcx>(
         .map(|op_arg| fx.monomorphize(op_arg.ty(fx.mir, fx.tcx)))
         .collect::<Vec<_>>();
     let fn_abi = if let Some(instance) = instance {
-        FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), instance, &extra_args)
+        RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(instance, &extra_args)
     } else {
-        FnAbi::of_fn_ptr(&RevealAllLayoutCx(fx.tcx), fn_ty.fn_sig(fx.tcx), &extra_args)
+        RevealAllLayoutCx(fx.tcx).fn_abi_of_fn_ptr(fn_ty.fn_sig(fx.tcx), &extra_args)
     };
 
     let is_cold = instance
@@ -525,7 +525,7 @@ pub(crate) fn codegen_drop<'tcx>(
                     def: ty::InstanceDef::Virtual(drop_instance.def_id(), 0),
                     substs: drop_instance.substs,
                 };
-                let fn_abi = FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), virtual_drop, &[]);
+                let fn_abi = RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(virtual_drop, &[]);
 
                 let sig = clif_sig_from_fn_abi(fx.tcx, fx.triple(), &fn_abi);
                 let sig = fx.bcx.import_signature(sig);
@@ -534,7 +534,7 @@ pub(crate) fn codegen_drop<'tcx>(
             _ => {
                 assert!(!matches!(drop_instance.def, InstanceDef::Virtual(_, _)));
 
-                let fn_abi = FnAbi::of_instance(&RevealAllLayoutCx(fx.tcx), drop_instance, &[]);
+                let fn_abi = RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(drop_instance, &[]);
 
                 let arg_value = drop_place.place_ref(
                     fx,
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index d29558a4e1f65..872c7edc791ff 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -3,8 +3,7 @@
 use cranelift_codegen::binemit::{NullStackMapSink, NullTrapSink};
 use rustc_index::vec::IndexVec;
 use rustc_middle::ty::adjustment::PointerCast;
-use rustc_middle::ty::layout::FnAbiExt;
-use rustc_target::abi::call::FnAbi;
+use rustc_middle::ty::layout::FnAbiOf;
 
 use crate::constant::ConstantCx;
 use crate::prelude::*;
@@ -62,7 +61,7 @@ pub(crate) fn codegen_fn<'tcx>(
         instance,
         symbol_name,
         mir,
-        fn_abi: Some(FnAbi::of_instance(&RevealAllLayoutCx(tcx), instance, &[])),
+        fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, &[])),
 
         bcx,
         block_map,
diff --git a/compiler/rustc_codegen_cranelift/src/common.rs b/compiler/rustc_codegen_cranelift/src/common.rs
index 06d1fc717cc92..4a8be89460fcf 100644
--- a/compiler/rustc_codegen_cranelift/src/common.rs
+++ b/compiler/rustc_codegen_cranelift/src/common.rs
@@ -1,5 +1,7 @@
 use rustc_index::vec::IndexVec;
-use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers};
+use rustc_middle::ty::layout::{
+    FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOfHelpers,
+};
 use rustc_middle::ty::SymbolName;
 use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::{Integer, Primitive};
@@ -266,6 +268,20 @@ impl<'tcx> LayoutOfHelpers<'tcx> for FunctionCx<'_, '_, 'tcx> {
     }
 }
 
+impl<'tcx> FnAbiOfHelpers<'tcx> for FunctionCx<'_, '_, 'tcx> {
+    type FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>;
+
+    #[inline]
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+    ) -> ! {
+        RevealAllLayoutCx(self.tcx).handle_fn_abi_err(err, span, fn_abi_request)
+    }
+}
+
 impl<'tcx> layout::HasTyCtxt<'tcx> for FunctionCx<'_, '_, 'tcx> {
     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
         self.tcx
@@ -378,6 +394,43 @@ impl<'tcx> LayoutOfHelpers<'tcx> for RevealAllLayoutCx<'tcx> {
     }
 }
 
+impl<'tcx> FnAbiOfHelpers<'tcx> for RevealAllLayoutCx<'tcx> {
+    type FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>;
+
+    #[inline]
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+    ) -> ! {
+        if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+            self.0.sess.span_fatal(span, &err.to_string())
+        } else {
+            match fn_abi_request {
+                FnAbiRequest::OfFnPtr { sig, extra_args } => {
+                    span_bug!(
+                        span,
+                        "`fn_abi_of_fn_ptr({}, {:?})` failed: {}",
+                        sig,
+                        extra_args,
+                        err
+                    );
+                }
+                FnAbiRequest::OfInstance { instance, extra_args } => {
+                    span_bug!(
+                        span,
+                        "`fn_abi_of_instance({}, {:?})` failed: {}",
+                        instance,
+                        extra_args,
+                        err
+                    );
+                }
+            }
+        }
+    }
+}
+
 impl<'tcx> layout::HasTyCtxt<'tcx> for RevealAllLayoutCx<'tcx> {
     fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
         self.0
diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
index 424a0d742d12b..5c4991f1fb667 100644
--- a/compiler/rustc_codegen_cranelift/src/constant.rs
+++ b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -129,9 +129,7 @@ pub(crate) fn codegen_constant<'tcx>(
     };
     let const_val = match const_.val {
         ConstKind::Value(const_val) => const_val,
-        ConstKind::Unevaluated(uv)
-            if fx.tcx.is_static(uv.def.did) =>
-        {
+        ConstKind::Unevaluated(uv) if fx.tcx.is_static(uv.def.did) => {
             assert!(uv.substs(fx.tcx).is_empty());
             assert!(uv.promoted.is_none());
 
diff --git a/compiler/rustc_codegen_cranelift/src/pretty_clif.rs b/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
index 05db74745a1c0..0b80ef1c04e76 100644
--- a/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
+++ b/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
@@ -61,9 +61,8 @@ use cranelift_codegen::{
     write::{FuncWriter, PlainWriter},
 };
 
-use rustc_middle::ty::layout::FnAbiExt;
+use rustc_middle::ty::layout::FnAbiOf;
 use rustc_session::config::OutputType;
-use rustc_target::abi::call::FnAbi;
 
 use crate::prelude::*;
 
@@ -81,7 +80,7 @@ impl CommentWriter {
             vec![
                 format!("symbol {}", tcx.symbol_name(instance).name),
                 format!("instance {:?}", instance),
-                format!("abi {:?}", FnAbi::of_instance(&RevealAllLayoutCx(tcx), instance, &[])),
+                format!("abi {:?}", RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, &[])),
                 String::new(),
             ]
         } else {
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 799f9a57e93a2..8e3aaf56382b1 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -15,10 +15,12 @@ use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::MemFlags;
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_hir::def_id::DefId;
-use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
+use rustc_middle::ty::layout::{
+    FnAbiError, FnAbiOfHelpers, FnAbiRequest, LayoutError, LayoutOfHelpers, TyAndLayout,
+};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
-use rustc_target::abi::{self, Align, Size, WrappingRange};
+use rustc_target::abi::{self, call::FnAbi, Align, Size, WrappingRange};
 use rustc_target::spec::{HasTargetSpec, Target};
 use std::borrow::Cow;
 use std::ffi::CStr;
@@ -97,6 +99,20 @@ impl LayoutOfHelpers<'tcx> for Builder<'_, '_, 'tcx> {
     }
 }
 
+impl FnAbiOfHelpers<'tcx> for Builder<'_, '_, 'tcx> {
+    type FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>;
+
+    #[inline]
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+    ) -> ! {
+        self.cx.handle_fn_abi_err(err, span, fn_abi_request)
+    }
+}
+
 impl Deref for Builder<'_, 'll, 'tcx> {
     type Target = CodegenCx<'ll, 'tcx>;
 
diff --git a/compiler/rustc_codegen_llvm/src/callee.rs b/compiler/rustc_codegen_llvm/src/callee.rs
index bb16c90cd12f1..1a2aea015b1af 100644
--- a/compiler/rustc_codegen_llvm/src/callee.rs
+++ b/compiler/rustc_codegen_llvm/src/callee.rs
@@ -4,7 +4,7 @@
 //! and methods are represented as just a fn ptr and not a full
 //! closure.
 
-use crate::abi::{FnAbi, FnAbiLlvmExt};
+use crate::abi::FnAbiLlvmExt;
 use crate::attributes;
 use crate::context::CodegenCx;
 use crate::llvm;
@@ -12,7 +12,7 @@ use crate::value::Value;
 use rustc_codegen_ssa::traits::*;
 use tracing::debug;
 
-use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt};
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt};
 use rustc_middle::ty::{self, Instance, TypeFoldable};
 
 /// Codegens a reference to a fn/method item, monomorphizing and
@@ -42,7 +42,7 @@ pub fn get_fn(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) -> &'ll Value
         sym
     );
 
-    let fn_abi = FnAbi::of_instance(cx, instance, &[]);
+    let fn_abi = cx.fn_abi_of_instance(instance, &[]);
 
     let llfn = if let Some(llfn) = cx.get_declared_value(&sym) {
         // Create a fn pointer with the new signature.
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 1d6efdf5f2510..f1a2968ce59b1 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -15,14 +15,19 @@ use rustc_data_structures::base_n;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_middle::mir::mono::CodegenUnit;
-use rustc_middle::ty::layout::{HasParamEnv, LayoutError, LayoutOfHelpers, TyAndLayout};
+use rustc_middle::ty::layout::{
+    FnAbiError, FnAbiOfHelpers, FnAbiRequest, HasParamEnv, LayoutError, LayoutOfHelpers,
+    TyAndLayout,
+};
 use rustc_middle::ty::{self, Instance, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::config::{CFGuard, CrateType, DebugInfo};
 use rustc_session::Session;
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
-use rustc_target::abi::{HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
+use rustc_target::abi::{
+    call::FnAbi, HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx,
+};
 use rustc_target::spec::{HasTargetSpec, RelocModel, Target, TlsModel};
 use smallvec::SmallVec;
 
@@ -853,3 +858,40 @@ impl LayoutOfHelpers<'tcx> for CodegenCx<'ll, 'tcx> {
         }
     }
 }
+
+impl FnAbiOfHelpers<'tcx> for CodegenCx<'ll, 'tcx> {
+    type FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>;
+
+    #[inline]
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+    ) -> ! {
+        if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+            self.sess().span_fatal(span, &err.to_string())
+        } else {
+            match fn_abi_request {
+                FnAbiRequest::OfFnPtr { sig, extra_args } => {
+                    span_bug!(
+                        span,
+                        "`fn_abi_of_fn_ptr({}, {:?})` failed: {}",
+                        sig,
+                        extra_args,
+                        err
+                    );
+                }
+                FnAbiRequest::OfInstance { instance, extra_args } => {
+                    span_bug!(
+                        span,
+                        "`fn_abi_of_instance({}, {:?})` failed: {}",
+                        instance,
+                        extra_args,
+                        err
+                    );
+                }
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
index 019bf4a09a787..cc1376278aaa4 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
@@ -1,6 +1,6 @@
 use crate::llvm;
 
-use crate::abi::{Abi, FnAbi};
+use crate::abi::Abi;
 use crate::builder::Builder;
 use crate::common::CodegenCx;
 
@@ -20,7 +20,7 @@ use rustc_middle::mir::coverage::{
     CodeRegion, CounterValueReference, ExpressionOperandId, InjectedExpressionId, Op,
 };
 use rustc_middle::ty;
-use rustc_middle::ty::layout::FnAbiExt;
+use rustc_middle::ty::layout::FnAbiOf;
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::Instance;
 
@@ -200,8 +200,7 @@ fn declare_unused_fn(cx: &CodegenCx<'ll, 'tcx>, def_id: &DefId) -> Instance<'tcx
 
     let llfn = cx.declare_fn(
         &tcx.symbol_name(instance).name,
-        &FnAbi::of_fn_ptr(
-            cx,
+        &cx.fn_abi_of_fn_ptr(
             ty::Binder::dummy(tcx.mk_fn_sig(
                 iter::once(tcx.mk_unit()),
                 tcx.mk_unit(),
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
index c2725b83f50d6..e5fd5bae01b74 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
@@ -3,12 +3,11 @@ use super::utils::DIB;
 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext};
 use rustc_codegen_ssa::traits::*;
 
-use crate::abi::FnAbi;
 use crate::common::CodegenCx;
 use crate::llvm;
 use crate::llvm::debuginfo::{DILocation, DIScope};
 use rustc_middle::mir::{Body, SourceScope};
-use rustc_middle::ty::layout::FnAbiExt;
+use rustc_middle::ty::layout::FnAbiOf;
 use rustc_middle::ty::{self, Instance};
 use rustc_session::config::DebugInfo;
 
@@ -94,7 +93,7 @@ fn make_mir_scope(
                 ty::ParamEnv::reveal_all(),
                 callee,
             );
-            let callee_fn_abi = FnAbi::of_instance(cx, callee, &[]);
+            let callee_fn_abi = cx.fn_abi_of_instance(callee, &[]);
             cx.dbg_scope_fn(callee, &callee_fn_abi, None)
         }
         None => unsafe {
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index 1060f911a9ed4..a046c518e1aa7 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -15,7 +15,7 @@ use rustc_codegen_ssa::mir::operand::OperandRef;
 use rustc_codegen_ssa::mir::place::PlaceRef;
 use rustc_codegen_ssa::traits::*;
 use rustc_hir as hir;
-use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt, LayoutOf};
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf};
 use rustc_middle::ty::{self, Ty};
 use rustc_middle::{bug, span_bug};
 use rustc_span::{sym, symbol::kw, Span, Symbol};
@@ -737,7 +737,7 @@ fn gen_fn<'ll, 'tcx>(
     rust_fn_sig: ty::PolyFnSig<'tcx>,
     codegen: &mut dyn FnMut(Builder<'_, 'll, 'tcx>),
 ) -> (&'ll Type, &'ll Value) {
-    let fn_abi = FnAbi::of_fn_ptr(cx, rust_fn_sig, &[]);
+    let fn_abi = cx.fn_abi_of_fn_ptr(rust_fn_sig, &[]);
     let llty = fn_abi.llvm_type(cx);
     let llfn = cx.declare_fn(name, &fn_abi);
     cx.set_frame_pointer_type(llfn);
diff --git a/compiler/rustc_codegen_llvm/src/mono_item.rs b/compiler/rustc_codegen_llvm/src/mono_item.rs
index 8ba3e870fbb71..b0301fa75aadf 100644
--- a/compiler/rustc_codegen_llvm/src/mono_item.rs
+++ b/compiler/rustc_codegen_llvm/src/mono_item.rs
@@ -1,4 +1,3 @@
-use crate::abi::FnAbi;
 use crate::attributes;
 use crate::base;
 use crate::context::CodegenCx;
@@ -8,7 +7,7 @@ use rustc_codegen_ssa::traits::*;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 pub use rustc_middle::mir::mono::MonoItem;
 use rustc_middle::mir::mono::{Linkage, Visibility};
-use rustc_middle::ty::layout::{FnAbiExt, LayoutOf};
+use rustc_middle::ty::layout::{FnAbiOf, LayoutOf};
 use rustc_middle::ty::{self, Instance, TypeFoldable};
 use rustc_session::config::CrateType;
 use rustc_target::spec::RelocModel;
@@ -53,7 +52,7 @@ impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     ) {
         assert!(!instance.substs.needs_infer());
 
-        let fn_abi = FnAbi::of_instance(self, instance, &[]);
+        let fn_abi = self.fn_abi_of_instance(instance, &[]);
         let lldecl = self.declare_fn(symbol_name, &fn_abi);
         unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
         let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
diff --git a/compiler/rustc_codegen_llvm/src/type_of.rs b/compiler/rustc_codegen_llvm/src/type_of.rs
index 3e39bf3e995a2..94ad84aadd84c 100644
--- a/compiler/rustc_codegen_llvm/src/type_of.rs
+++ b/compiler/rustc_codegen_llvm/src/type_of.rs
@@ -1,10 +1,9 @@
-use crate::abi::FnAbi;
 use crate::common::*;
 use crate::context::TypeLowering;
 use crate::type_::Type;
 use rustc_codegen_ssa::traits::*;
 use rustc_middle::bug;
-use rustc_middle::ty::layout::{FnAbiExt, LayoutOf, TyAndLayout};
+use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, Ty, TypeFoldable};
 use rustc_target::abi::{Abi, AddressSpace, Align, FieldsShape};
@@ -231,7 +230,7 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
                 ty::Adt(def, _) if def.is_box() => {
                     cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).llvm_type(cx))
                 }
-                ty::FnPtr(sig) => cx.fn_ptr_backend_type(&FnAbi::of_fn_ptr(cx, sig, &[])),
+                ty::FnPtr(sig) => cx.fn_ptr_backend_type(&cx.fn_abi_of_fn_ptr(sig, &[])),
                 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO),
             };
             cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index c557946afbc4b..fac72c39b5e68 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -14,7 +14,7 @@ use rustc_hir::lang_items::LangItem;
 use rustc_index::vec::Idx;
 use rustc_middle::mir::AssertKind;
 use rustc_middle::mir::{self, SwitchTargets};
-use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt, LayoutOf};
+use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self, Instance, Ty, TypeFoldable};
 use rustc_span::source_map::Span;
@@ -337,7 +337,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
                     substs: drop_fn.substs,
                 };
-                let fn_abi = FnAbi::of_instance(&bx, virtual_drop, &[]);
+                let fn_abi = bx.fn_abi_of_instance(virtual_drop, &[]);
                 let vtable = args[1];
                 args = &args[..1];
                 (
@@ -346,7 +346,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     fn_abi,
                 )
             }
-            _ => (bx.get_fn_addr(drop_fn), FnAbi::of_instance(&bx, drop_fn, &[])),
+            _ => (bx.get_fn_addr(drop_fn), bx.fn_abi_of_instance(drop_fn, &[])),
         };
         helper.do_call(
             self,
@@ -433,7 +433,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         // Obtain the panic entry point.
         let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item);
         let instance = ty::Instance::mono(bx.tcx(), def_id);
-        let fn_abi = FnAbi::of_instance(&bx, instance, &[]);
+        let fn_abi = bx.fn_abi_of_instance(instance, &[]);
         let llfn = bx.get_fn_addr(instance);
 
         // Codegen the actual panic invoke/call.
@@ -494,7 +494,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let def_id =
                     common::langcall(bx.tcx(), Some(source_info.span), "", LangItem::Panic);
                 let instance = ty::Instance::mono(bx.tcx(), def_id);
-                let fn_abi = FnAbi::of_instance(bx, instance, &[]);
+                let fn_abi = bx.fn_abi_of_instance(instance, &[]);
                 let llfn = bx.get_fn_addr(instance);
 
                 // Codegen the actual panic invoke/call.
@@ -579,8 +579,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             .collect::<Vec<_>>();
 
         let fn_abi = match instance {
-            Some(instance) => FnAbi::of_instance(&bx, instance, &extra_args),
-            None => FnAbi::of_fn_ptr(&bx, sig, &extra_args),
+            Some(instance) => bx.fn_abi_of_instance(instance, &extra_args),
+            None => bx.fn_abi_of_fn_ptr(sig, &extra_args),
         };
 
         if intrinsic == Some(sym::transmute) {
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 2c7636f1913dd..3fd9dc08c2be2 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -2,7 +2,7 @@ use crate::traits::*;
 use rustc_errors::ErrorReported;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
-use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt, TyAndLayout};
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
 use rustc_middle::ty::{self, Instance, Ty, TypeFoldable};
 use rustc_target::abi::call::{FnAbi, PassMode};
 
@@ -139,7 +139,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
     let mir = cx.tcx().instance_mir(instance.def);
 
-    let fn_abi = FnAbi::of_instance(cx, instance, &[]);
+    let fn_abi = cx.fn_abi_of_instance(instance, &[]);
     debug!("fn_abi: {:?}", fn_abi);
 
     let debug_context = cx.create_function_debug_context(instance, &fn_abi, llfn, &mir);
diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index dbb7e1ee8b17f..82b79fd0b2ac3 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -8,14 +8,15 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::ErrorReported;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::middle::cstore::{EncodedMetadata, MetadataLoaderDyn};
-use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf, TyAndLayout};
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_session::{
     config::{self, OutputFilenames, PrintRequest},
     Session,
 };
 use rustc_span::symbol::Symbol;
+use rustc_target::abi::call::FnAbi;
 use rustc_target::spec::Target;
 
 pub use rustc_data_structures::sync::MetadataRef;
@@ -38,12 +39,19 @@ pub trait BackendTypes {
 }
 
 pub trait Backend<'tcx>:
-    Sized + BackendTypes + HasTyCtxt<'tcx> + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
+    Sized
+    + BackendTypes
+    + HasTyCtxt<'tcx>
+    + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
+    + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
 {
 }
 
 impl<'tcx, T> Backend<'tcx> for T where
-    Self: BackendTypes + HasTyCtxt<'tcx> + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
+    Self: BackendTypes
+        + HasTyCtxt<'tcx>
+        + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
+        + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
 {
 }
 
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 42ac77054190a..04d8eaf7c9f80 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -2035,6 +2035,12 @@ impl<'tcx> HasDataLayout for ty::query::TyCtxtAt<'tcx> {
     }
 }
 
+impl<'tcx> HasTargetSpec for ty::query::TyCtxtAt<'tcx> {
+    fn target_spec(&self) -> &Target {
+        &self.sess.target
+    }
+}
+
 impl<'tcx> HasTyCtxt<'tcx> for ty::query::TyCtxtAt<'tcx> {
     #[inline]
     fn tcx(&self) -> TyCtxt<'tcx> {
@@ -2142,10 +2148,10 @@ pub trait LayoutOf<'tcx>: LayoutOfHelpers<'tcx> {
     #[inline]
     fn spanned_layout_of(&self, ty: Ty<'tcx>, span: Span) -> Self::LayoutOfResult {
         let span = if !span.is_dummy() { span } else { self.layout_tcx_at_span() };
+        let tcx = self.tcx().at(span);
+
         MaybeResult::from(
-            self.tcx()
-                .at(span)
-                .layout_of(self.param_env().and(ty))
+            tcx.layout_of(self.param_env().and(ty))
                 .map_err(|err| self.handle_layout_err(err, span, ty)),
         )
     }
@@ -2545,10 +2551,10 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for LayoutError<'tcx> {
 
 impl<'tcx> ty::Instance<'tcx> {
     // NOTE(eddyb) this is private to avoid using it from outside of
-    // `FnAbi::of_instance` - any other uses are either too high-level
+    // `fn_abi_of_instance` - any other uses are either too high-level
     // for `Instance` (e.g. typeck would use `Ty::fn_sig` instead),
     // or should go through `FnAbi` instead, to avoid losing any
-    // adjustments `FnAbi::of_instance` might be performing.
+    // adjustments `fn_abi_of_instance` might be performing.
     fn fn_sig_for_fn_abi(&self, tcx: TyCtxt<'tcx>) -> ty::PolyFnSig<'tcx> {
         // FIXME(davidtwco,eddyb): A `ParamEnv` should be passed through to this function.
         let ty = self.ty(tcx, ty::ParamEnv::reveal_all());
@@ -2801,7 +2807,7 @@ pub fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
 }
 
 /// Error produced by attempting to compute or adjust a `FnAbi`.
-enum FnAbiError<'tcx> {
+pub enum FnAbiError<'tcx> {
     /// Error produced by a `layout_of` call, while computing `FnAbi` initially.
     Layout(LayoutError<'tcx>),
 
@@ -2830,125 +2836,124 @@ impl<'tcx> fmt::Display for FnAbiError<'tcx> {
     }
 }
 
-pub trait FnAbiExt<'tcx, C>
-where
-    C: HasTyCtxt<'tcx> + HasParamEnv<'tcx>,
-{
+// FIXME(eddyb) maybe use something like this for an unified `fn_abi_of`, not
+// just for error handling.
+#[derive(Debug)]
+pub enum FnAbiRequest<'a, 'tcx> {
+    OfFnPtr { sig: ty::PolyFnSig<'tcx>, extra_args: &'a [Ty<'tcx>] },
+    OfInstance { instance: ty::Instance<'tcx>, extra_args: &'a [Ty<'tcx>] },
+}
+
+/// Trait for contexts that want to be able to compute `FnAbi`s.
+/// This automatically gives access to `FnAbiOf`, through a blanket `impl`.
+pub trait FnAbiOfHelpers<'tcx>: LayoutOfHelpers<'tcx> {
+    /// The `&FnAbi`-wrapping type (or `&FnAbi` itself), which will be
+    /// returned from `fn_abi_of_*` (see also `handle_fn_abi_err`).
+    type FnAbiOfResult: MaybeResult<&'tcx FnAbi<'tcx, Ty<'tcx>>>;
+
+    /// Helper used for `fn_abi_of_*`, to adapt `tcx.fn_abi_of_*(...)` into a
+    /// `Self::FnAbiOfResult` (which does not need to be a `Result<...>`).
+    ///
+    /// Most `impl`s, which propagate `FnAbiError`s, should simply return `err`,
+    /// but this hook allows e.g. codegen to return only `&FnABi` from its
+    /// `cx.fn_abi_of_*(...)`, without any `Result<...>` around it to deal with
+    /// (and any `FnAbiError`s are turned into fatal errors or ICEs).
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+    ) -> <Self::FnAbiOfResult as MaybeResult<&'tcx FnAbi<'tcx, Ty<'tcx>>>>::Error;
+}
+
+/// Blanket extension trait for contexts that can compute `FnAbi`s.
+pub trait FnAbiOf<'tcx>: FnAbiOfHelpers<'tcx> {
     /// Compute a `FnAbi` suitable for indirect calls, i.e. to `fn` pointers.
     ///
-    /// NB: this doesn't handle virtual calls - those should use `FnAbi::of_instance`
+    /// NB: this doesn't handle virtual calls - those should use `fn_abi_of_instance`
     /// instead, where the instance is an `InstanceDef::Virtual`.
-    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self;
+    #[inline]
+    fn fn_abi_of_fn_ptr(
+        &self,
+        sig: ty::PolyFnSig<'tcx>,
+        extra_args: &[Ty<'tcx>],
+    ) -> Self::FnAbiOfResult {
+        // FIXME(eddyb) get a better `span` here.
+        let span = self.layout_tcx_at_span();
+        let cx = LayoutCx { tcx: self.tcx().at(span), param_env: self.param_env() };
+
+        MaybeResult::from(
+            cx.fn_abi_new_internal(sig, extra_args, None, CodegenFnAttrFlags::empty(), false)
+                .map_err(|err| {
+                    self.handle_fn_abi_err(err, span, FnAbiRequest::OfFnPtr { sig, extra_args })
+                }),
+        )
+    }
 
     /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for
     /// direct calls to an `fn`.
     ///
     /// NB: that includes virtual calls, which are represented by "direct calls"
     /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`).
-    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self;
-}
-
-impl<'tcx, C> FnAbiExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
-where
-    C: HasTyCtxt<'tcx> + HasParamEnv<'tcx>,
-{
-    fn of_fn_ptr(cx: &C, sig: ty::PolyFnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self {
-        call::FnAbi::new_internal(
-            &LayoutCx { tcx: cx.tcx(), param_env: cx.param_env() },
-            sig,
-            extra_args,
-            None,
-            CodegenFnAttrFlags::empty(),
-            false,
-        )
-        .unwrap_or_else(|err| {
-            // FIXME(eddyb) get a better `span` here.
-            let span = DUMMY_SP;
-            if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
-                cx.tcx().sess.span_fatal(span, &err.to_string())
-            } else {
-                span_bug!(span, "`FnAbi::of_fn_ptr({}, {:?})` failed: {}", sig, extra_args, err);
-            }
-        })
-    }
+    #[inline]
+    fn fn_abi_of_instance(
+        &self,
+        instance: ty::Instance<'tcx>,
+        extra_args: &[Ty<'tcx>],
+    ) -> Self::FnAbiOfResult {
+        // FIXME(eddyb) get a better `span` here.
+        let span = self.layout_tcx_at_span();
+        let cx = LayoutCx { tcx: self.tcx().at(span), param_env: self.param_env() };
 
-    fn of_instance(cx: &C, instance: ty::Instance<'tcx>, extra_args: &[Ty<'tcx>]) -> &'tcx Self {
         let sig = instance.fn_sig_for_fn_abi(cx.tcx());
 
         let caller_location = if instance.def.requires_caller_location(cx.tcx()) {
-            Some(cx.tcx().caller_location_ty())
+            Some(cx.tcx.caller_location_ty())
         } else {
             None
         };
 
-        let attrs = cx.tcx().codegen_fn_attrs(instance.def_id()).flags;
+        let attrs = cx.tcx.codegen_fn_attrs(instance.def_id()).flags;
 
-        call::FnAbi::new_internal(
-            &LayoutCx { tcx: cx.tcx(), param_env: cx.param_env() },
-            sig,
-            extra_args,
-            caller_location,
-            attrs,
-            matches!(instance.def, ty::InstanceDef::Virtual(..)),
+        MaybeResult::from(
+            cx.fn_abi_new_internal(
+                sig,
+                extra_args,
+                caller_location,
+                attrs,
+                matches!(instance.def, ty::InstanceDef::Virtual(..)),
+            )
+            .map_err(|err| {
+                // HACK(eddyb) at least for definitions of/calls to `Instance`s,
+                // we can get some kind of span even if one wasn't provided.
+                // However, we don't do this early in order to avoid calling
+                // `def_span` unconditionally (which may have a perf penalty).
+                let span = if !span.is_dummy() { span } else { cx.tcx.def_span(instance.def_id()) };
+                self.handle_fn_abi_err(err, span, FnAbiRequest::OfInstance { instance, extra_args })
+            }),
         )
-        .unwrap_or_else(|err| {
-            // FIXME(eddyb) get a better `span` here.
-            let span = cx.tcx().def_span(instance.def_id());
-            if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
-                cx.tcx().sess.span_fatal(span, &err.to_string())
-            } else {
-                span_bug!(
-                    span,
-                    "`FnAbi::of_instance({}, {:?})` failed: {}",
-                    instance,
-                    extra_args,
-                    err
-                );
-            }
-        })
     }
 }
 
-/// Implementation detail of computing `FnAbi`s, shouldn't be exported.
-// FIXME(eddyb) move this off of being generic on `C: LayoutOf`, and
-// explicitly take `LayoutCx` *or* `TyCtxt` and `ParamEnvAnd<...>`.
-trait FnAbiInternalExt<'tcx, C>
-where
-    C: LayoutOf<'tcx, LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>>
-        + HasTargetSpec,
-{
+impl<C: FnAbiOfHelpers<'tcx>> FnAbiOf<'tcx> for C {}
+
+impl<'tcx> LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> {
     // FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
     // arguments of this method, into a separate `struct`.
-    fn new_internal(
-        cx: &C,
+    fn fn_abi_new_internal(
+        &self,
         sig: ty::PolyFnSig<'tcx>,
         extra_args: &[Ty<'tcx>],
         caller_location: Option<Ty<'tcx>>,
         codegen_fn_attr_flags: CodegenFnAttrFlags,
         // FIXME(eddyb) replace this with something typed, like an `enum`.
-        make_self_ptr_thin: bool,
-    ) -> Result<&'tcx Self, FnAbiError<'tcx>>;
-    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) -> Result<(), FnAbiError<'tcx>>;
-}
-
-impl<'tcx, C> FnAbiInternalExt<'tcx, C> for call::FnAbi<'tcx, Ty<'tcx>>
-where
-    C: LayoutOf<'tcx, LayoutOfResult = Result<TyAndLayout<'tcx>, LayoutError<'tcx>>>
-        + HasTargetSpec,
-{
-    fn new_internal(
-        cx: &C,
-        sig: ty::PolyFnSig<'tcx>,
-        extra_args: &[Ty<'tcx>],
-        caller_location: Option<Ty<'tcx>>,
-        codegen_fn_attr_flags: CodegenFnAttrFlags,
         force_thin_self_ptr: bool,
-    ) -> Result<&'tcx Self, FnAbiError<'tcx>> {
+    ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
         debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args);
 
-        let sig = cx.tcx().normalize_erasing_late_bound_regions(cx.param_env(), sig);
+        let sig = self.tcx.normalize_erasing_late_bound_regions(self.param_env, sig);
 
-        let conv = conv_from_spec_abi(cx.tcx(), sig.abi);
+        let conv = conv_from_spec_abi(self.tcx(), sig.abi);
 
         let mut inputs = sig.inputs();
         let extra_args = if sig.abi == RustCall {
@@ -2975,7 +2980,7 @@ where
             extra_args.to_vec()
         };
 
-        let target = &cx.tcx().sess.target;
+        let target = &self.tcx.sess.target;
         let target_env_gnu_like = matches!(&target.env[..], "gnu" | "musl");
         let win_x64_gnu = target.os == "windows" && target.arch == "x86_64" && target.env == "gnu";
         let linux_s390x_gnu_like =
@@ -3008,7 +3013,7 @@ where
                 attrs.set(ArgAttribute::NonNull);
             }
 
-            if let Some(pointee) = layout.pointee_info_at(cx, offset) {
+            if let Some(pointee) = layout.pointee_info_at(self, offset) {
                 if let Some(kind) = pointee.safe {
                     attrs.pointee_align = Some(pointee.align);
 
@@ -3055,17 +3060,17 @@ where
         let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
             let is_return = arg_idx.is_none();
 
-            let layout = cx.layout_of(ty)?;
+            let layout = self.layout_of(ty)?;
             let layout = if force_thin_self_ptr && arg_idx == Some(0) {
                 // Don't pass the vtable, it's not an argument of the virtual fn.
                 // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
                 // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
-                make_thin_self_ptr(cx, layout)
+                make_thin_self_ptr(self, layout)
             } else {
                 layout
             };
 
-            let mut arg = ArgAbi::new(cx, layout, |layout, scalar, offset| {
+            let mut arg = ArgAbi::new(self, layout, |layout, scalar, offset| {
                 let mut attrs = ArgAttributes::new();
                 adjust_for_rust_scalar(&mut attrs, scalar, *layout, offset, is_return);
                 attrs
@@ -3102,14 +3107,18 @@ where
             c_variadic: sig.c_variadic,
             fixed_count: inputs.len(),
             conv,
-            can_unwind: fn_can_unwind(cx.tcx(), codegen_fn_attr_flags, sig.abi),
+            can_unwind: fn_can_unwind(self.tcx(), codegen_fn_attr_flags, sig.abi),
         };
-        fn_abi.adjust_for_abi(cx, sig.abi)?;
+        self.fn_abi_adjust_for_abi(&mut fn_abi, sig.abi)?;
         debug!("FnAbi::new_internal = {:?}", fn_abi);
-        Ok(cx.tcx().intern_fn_abi(fn_abi))
+        Ok(self.tcx.intern_fn_abi(fn_abi))
     }
 
-    fn adjust_for_abi(&mut self, cx: &C, abi: SpecAbi) -> Result<(), FnAbiError<'tcx>> {
+    fn fn_abi_adjust_for_abi(
+        &self,
+        fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
+        abi: SpecAbi,
+    ) -> Result<(), FnAbiError<'tcx>> {
         if abi == SpecAbi::Unadjusted {
             return Ok(());
         }
@@ -3148,7 +3157,7 @@ where
                     // anyway, we control all calls to it in libstd.
                     Abi::Vector { .. }
                         if abi != SpecAbi::PlatformIntrinsic
-                            && cx.tcx().sess.target.simd_types_indirect =>
+                            && self.tcx.sess.target.simd_types_indirect =>
                     {
                         arg.make_indirect();
                         return;
@@ -3159,7 +3168,7 @@ where
 
                 // Pass and return structures up to 2 pointers in size by value, matching `ScalarPair`.
                 // LLVM will usually pass these in 2 registers, which is more efficient than by-ref.
-                let max_by_val_size = Pointer.size(cx) * 2;
+                let max_by_val_size = Pointer.size(self) * 2;
                 let size = arg.layout.size;
 
                 if arg.layout.is_unsized() || size > max_by_val_size {
@@ -3171,12 +3180,12 @@ where
                     arg.cast_to(Reg { kind: RegKind::Integer, size });
                 }
             };
-            fixup(&mut self.ret);
-            for arg in &mut self.args {
+            fixup(&mut fn_abi.ret);
+            for arg in &mut fn_abi.args {
                 fixup(arg);
             }
         } else {
-            self.adjust_for_foreign_abi(cx, abi)?;
+            fn_abi.adjust_for_foreign_abi(self, abi)?;
         }
 
         Ok(())

From c1837ef1c58edd48c81341126ecc94e7adc5bd3d Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Thu, 2 Sep 2021 00:29:15 +0300
Subject: [PATCH 09/10] Querify `fn_abi_of_{fn_ptr,instance}`.

---
 .../rustc_codegen_cranelift/src/abi/mod.rs    |  23 ++--
 compiler/rustc_codegen_cranelift/src/base.rs  |   2 +-
 .../rustc_codegen_cranelift/src/common.rs     |   4 +-
 .../src/pretty_clif.rs                        |   5 +-
 compiler/rustc_codegen_llvm/src/builder.rs    |   2 +-
 compiler/rustc_codegen_llvm/src/callee.rs     |   2 +-
 compiler/rustc_codegen_llvm/src/context.rs    |   2 +-
 .../src/coverageinfo/mod.rs                   |   2 +-
 .../src/debuginfo/create_scope_map.rs         |   2 +-
 compiler/rustc_codegen_llvm/src/intrinsic.rs  |   2 +-
 compiler/rustc_codegen_llvm/src/mono_item.rs  |   2 +-
 compiler/rustc_codegen_llvm/src/type_of.rs    |   4 +-
 compiler/rustc_codegen_ssa/src/mir/block.rs   |  23 ++--
 compiler/rustc_codegen_ssa/src/mir/mod.rs     |   2 +-
 compiler/rustc_middle/src/query/mod.rs        |  21 +++
 compiler/rustc_middle/src/ty/layout.rs        | 123 +++++++++---------
 compiler/rustc_middle/src/ty/query.rs         |   1 +
 compiler/rustc_query_impl/src/keys.rs         |  22 ++++
 compiler/rustc_target/src/abi/call/mod.rs     |   1 +
 19 files changed, 152 insertions(+), 93 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/src/abi/mod.rs b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
index 6317e1d5d1aba..15bb90678059d 100644
--- a/compiler/rustc_codegen_cranelift/src/abi/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/abi/mod.rs
@@ -53,7 +53,11 @@ pub(crate) fn get_function_sig<'tcx>(
     inst: Instance<'tcx>,
 ) -> Signature {
     assert!(!inst.substs.needs_infer());
-    clif_sig_from_fn_abi(tcx, triple, &RevealAllLayoutCx(tcx).fn_abi_of_instance(inst, &[]))
+    clif_sig_from_fn_abi(
+        tcx,
+        triple,
+        &RevealAllLayoutCx(tcx).fn_abi_of_instance(inst, ty::List::empty()),
+    )
 }
 
 /// Instance must be monomorphized
@@ -350,14 +354,13 @@ pub(crate) fn codegen_terminator_call<'tcx>(
     };
 
     let extra_args = &args[fn_sig.inputs().len()..];
-    let extra_args = extra_args
-        .iter()
-        .map(|op_arg| fx.monomorphize(op_arg.ty(fx.mir, fx.tcx)))
-        .collect::<Vec<_>>();
+    let extra_args = fx
+        .tcx
+        .mk_type_list(extra_args.iter().map(|op_arg| fx.monomorphize(op_arg.ty(fx.mir, fx.tcx))));
     let fn_abi = if let Some(instance) = instance {
-        RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(instance, &extra_args)
+        RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(instance, extra_args)
     } else {
-        RevealAllLayoutCx(fx.tcx).fn_abi_of_fn_ptr(fn_ty.fn_sig(fx.tcx), &extra_args)
+        RevealAllLayoutCx(fx.tcx).fn_abi_of_fn_ptr(fn_ty.fn_sig(fx.tcx), extra_args)
     };
 
     let is_cold = instance
@@ -525,7 +528,8 @@ pub(crate) fn codegen_drop<'tcx>(
                     def: ty::InstanceDef::Virtual(drop_instance.def_id(), 0),
                     substs: drop_instance.substs,
                 };
-                let fn_abi = RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(virtual_drop, &[]);
+                let fn_abi =
+                    RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(virtual_drop, ty::List::empty());
 
                 let sig = clif_sig_from_fn_abi(fx.tcx, fx.triple(), &fn_abi);
                 let sig = fx.bcx.import_signature(sig);
@@ -534,7 +538,8 @@ pub(crate) fn codegen_drop<'tcx>(
             _ => {
                 assert!(!matches!(drop_instance.def, InstanceDef::Virtual(_, _)));
 
-                let fn_abi = RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(drop_instance, &[]);
+                let fn_abi =
+                    RevealAllLayoutCx(fx.tcx).fn_abi_of_instance(drop_instance, ty::List::empty());
 
                 let arg_value = drop_place.place_ref(
                     fx,
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index 872c7edc791ff..d8fa2c7690468 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -61,7 +61,7 @@ pub(crate) fn codegen_fn<'tcx>(
         instance,
         symbol_name,
         mir,
-        fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, &[])),
+        fn_abi: Some(RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, ty::List::empty())),
 
         bcx,
         block_map,
diff --git a/compiler/rustc_codegen_cranelift/src/common.rs b/compiler/rustc_codegen_cranelift/src/common.rs
index 4a8be89460fcf..0e84681d9ad94 100644
--- a/compiler/rustc_codegen_cranelift/src/common.rs
+++ b/compiler/rustc_codegen_cranelift/src/common.rs
@@ -276,7 +276,7 @@ impl<'tcx> FnAbiOfHelpers<'tcx> for FunctionCx<'_, '_, 'tcx> {
         &self,
         err: FnAbiError<'tcx>,
         span: Span,
-        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+        fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
         RevealAllLayoutCx(self.tcx).handle_fn_abi_err(err, span, fn_abi_request)
     }
@@ -402,7 +402,7 @@ impl<'tcx> FnAbiOfHelpers<'tcx> for RevealAllLayoutCx<'tcx> {
         &self,
         err: FnAbiError<'tcx>,
         span: Span,
-        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+        fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
         if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
             self.0.sess.span_fatal(span, &err.to_string())
diff --git a/compiler/rustc_codegen_cranelift/src/pretty_clif.rs b/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
index 0b80ef1c04e76..ec846d71960b8 100644
--- a/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
+++ b/compiler/rustc_codegen_cranelift/src/pretty_clif.rs
@@ -80,7 +80,10 @@ impl CommentWriter {
             vec![
                 format!("symbol {}", tcx.symbol_name(instance).name),
                 format!("instance {:?}", instance),
-                format!("abi {:?}", RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, &[])),
+                format!(
+                    "abi {:?}",
+                    RevealAllLayoutCx(tcx).fn_abi_of_instance(instance, ty::List::empty())
+                ),
                 String::new(),
             ]
         } else {
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 8e3aaf56382b1..dab7d3eaa8cfd 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -107,7 +107,7 @@ impl FnAbiOfHelpers<'tcx> for Builder<'_, '_, 'tcx> {
         &self,
         err: FnAbiError<'tcx>,
         span: Span,
-        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+        fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
         self.cx.handle_fn_abi_err(err, span, fn_abi_request)
     }
diff --git a/compiler/rustc_codegen_llvm/src/callee.rs b/compiler/rustc_codegen_llvm/src/callee.rs
index 1a2aea015b1af..a96ba148a6ce3 100644
--- a/compiler/rustc_codegen_llvm/src/callee.rs
+++ b/compiler/rustc_codegen_llvm/src/callee.rs
@@ -42,7 +42,7 @@ pub fn get_fn(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'tcx>) -> &'ll Value
         sym
     );
 
-    let fn_abi = cx.fn_abi_of_instance(instance, &[]);
+    let fn_abi = cx.fn_abi_of_instance(instance, ty::List::empty());
 
     let llfn = if let Some(llfn) = cx.get_declared_value(&sym) {
         // Create a fn pointer with the new signature.
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index f1a2968ce59b1..52a12b2fd81d8 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -867,7 +867,7 @@ impl FnAbiOfHelpers<'tcx> for CodegenCx<'ll, 'tcx> {
         &self,
         err: FnAbiError<'tcx>,
         span: Span,
-        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+        fn_abi_request: FnAbiRequest<'tcx>,
     ) -> ! {
         if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
             self.sess().span_fatal(span, &err.to_string())
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
index cc1376278aaa4..093aceda2b741 100644
--- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
@@ -208,7 +208,7 @@ fn declare_unused_fn(cx: &CodegenCx<'ll, 'tcx>, def_id: &DefId) -> Instance<'tcx
                 hir::Unsafety::Unsafe,
                 Abi::Rust,
             )),
-            &[],
+            ty::List::empty(),
         ),
     );
 
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
index e5fd5bae01b74..1612922d43953 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/create_scope_map.rs
@@ -93,7 +93,7 @@ fn make_mir_scope(
                 ty::ParamEnv::reveal_all(),
                 callee,
             );
-            let callee_fn_abi = cx.fn_abi_of_instance(callee, &[]);
+            let callee_fn_abi = cx.fn_abi_of_instance(callee, ty::List::empty());
             cx.dbg_scope_fn(callee, &callee_fn_abi, None)
         }
         None => unsafe {
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index a046c518e1aa7..9d0e0e6394434 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -737,7 +737,7 @@ fn gen_fn<'ll, 'tcx>(
     rust_fn_sig: ty::PolyFnSig<'tcx>,
     codegen: &mut dyn FnMut(Builder<'_, 'll, 'tcx>),
 ) -> (&'ll Type, &'ll Value) {
-    let fn_abi = cx.fn_abi_of_fn_ptr(rust_fn_sig, &[]);
+    let fn_abi = cx.fn_abi_of_fn_ptr(rust_fn_sig, ty::List::empty());
     let llty = fn_abi.llvm_type(cx);
     let llfn = cx.declare_fn(name, &fn_abi);
     cx.set_frame_pointer_type(llfn);
diff --git a/compiler/rustc_codegen_llvm/src/mono_item.rs b/compiler/rustc_codegen_llvm/src/mono_item.rs
index b0301fa75aadf..34982f769d03a 100644
--- a/compiler/rustc_codegen_llvm/src/mono_item.rs
+++ b/compiler/rustc_codegen_llvm/src/mono_item.rs
@@ -52,7 +52,7 @@ impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
     ) {
         assert!(!instance.substs.needs_infer());
 
-        let fn_abi = self.fn_abi_of_instance(instance, &[]);
+        let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty());
         let lldecl = self.declare_fn(symbol_name, &fn_abi);
         unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
         let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
diff --git a/compiler/rustc_codegen_llvm/src/type_of.rs b/compiler/rustc_codegen_llvm/src/type_of.rs
index 94ad84aadd84c..757ccbddbeedf 100644
--- a/compiler/rustc_codegen_llvm/src/type_of.rs
+++ b/compiler/rustc_codegen_llvm/src/type_of.rs
@@ -230,7 +230,9 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
                 ty::Adt(def, _) if def.is_box() => {
                     cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).llvm_type(cx))
                 }
-                ty::FnPtr(sig) => cx.fn_ptr_backend_type(&cx.fn_abi_of_fn_ptr(sig, &[])),
+                ty::FnPtr(sig) => {
+                    cx.fn_ptr_backend_type(&cx.fn_abi_of_fn_ptr(sig, ty::List::empty()))
+                }
                 _ => self.scalar_llvm_type_at(cx, scalar, Size::ZERO),
             };
             cx.scalar_lltypes.borrow_mut().insert(self.ty, llty);
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index fac72c39b5e68..cc9dd378ee497 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -337,7 +337,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
                     substs: drop_fn.substs,
                 };
-                let fn_abi = bx.fn_abi_of_instance(virtual_drop, &[]);
+                let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
                 let vtable = args[1];
                 args = &args[..1];
                 (
@@ -346,7 +346,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     fn_abi,
                 )
             }
-            _ => (bx.get_fn_addr(drop_fn), bx.fn_abi_of_instance(drop_fn, &[])),
+            _ => (bx.get_fn_addr(drop_fn), bx.fn_abi_of_instance(drop_fn, ty::List::empty())),
         };
         helper.do_call(
             self,
@@ -433,7 +433,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         // Obtain the panic entry point.
         let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item);
         let instance = ty::Instance::mono(bx.tcx(), def_id);
-        let fn_abi = bx.fn_abi_of_instance(instance, &[]);
+        let fn_abi = bx.fn_abi_of_instance(instance, ty::List::empty());
         let llfn = bx.get_fn_addr(instance);
 
         // Codegen the actual panic invoke/call.
@@ -494,7 +494,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let def_id =
                     common::langcall(bx.tcx(), Some(source_info.span), "", LangItem::Panic);
                 let instance = ty::Instance::mono(bx.tcx(), def_id);
-                let fn_abi = bx.fn_abi_of_instance(instance, &[]);
+                let fn_abi = bx.fn_abi_of_instance(instance, ty::List::empty());
                 let llfn = bx.get_fn_addr(instance);
 
                 // Codegen the actual panic invoke/call.
@@ -570,17 +570,14 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         };
 
         let extra_args = &args[sig.inputs().skip_binder().len()..];
-        let extra_args = extra_args
-            .iter()
-            .map(|op_arg| {
-                let op_ty = op_arg.ty(self.mir, bx.tcx());
-                self.monomorphize(op_ty)
-            })
-            .collect::<Vec<_>>();
+        let extra_args = bx.tcx().mk_type_list(extra_args.iter().map(|op_arg| {
+            let op_ty = op_arg.ty(self.mir, bx.tcx());
+            self.monomorphize(op_ty)
+        }));
 
         let fn_abi = match instance {
-            Some(instance) => bx.fn_abi_of_instance(instance, &extra_args),
-            None => bx.fn_abi_of_fn_ptr(sig, &extra_args),
+            Some(instance) => bx.fn_abi_of_instance(instance, extra_args),
+            None => bx.fn_abi_of_fn_ptr(sig, extra_args),
         };
 
         if intrinsic == Some(sym::transmute) {
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index 3fd9dc08c2be2..9ad2a66bc6aec 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -139,7 +139,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
 
     let mir = cx.tcx().instance_mir(instance.def);
 
-    let fn_abi = cx.fn_abi_of_instance(instance, &[]);
+    let fn_abi = cx.fn_abi_of_instance(instance, ty::List::empty());
     debug!("fn_abi: {:?}", fn_abi);
 
     let debug_context = cx.create_function_debug_context(instance, &fn_abi, llfn, &mir);
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 4296acce1ffbe..6a1ebbba817db 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -1128,6 +1128,27 @@ rustc_queries! {
         desc { "computing layout of `{}`", key.value }
     }
 
+    /// Compute a `FnAbi` suitable for indirect calls, i.e. to `fn` pointers.
+    ///
+    /// NB: this doesn't handle virtual calls - those should use `fn_abi_of_instance`
+    /// instead, where the instance is an `InstanceDef::Virtual`.
+    query fn_abi_of_fn_ptr(
+        key: ty::ParamEnvAnd<'tcx, (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>)>
+    ) -> Result<&'tcx abi::call::FnAbi<'tcx, Ty<'tcx>>, ty::layout::FnAbiError<'tcx>> {
+        desc { "computing call ABI of `{}` function pointers", key.value.0 }
+    }
+
+    /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for
+    /// direct calls to an `fn`.
+    ///
+    /// NB: that includes virtual calls, which are represented by "direct calls"
+    /// to an `InstanceDef::Virtual` instance (of `<dyn Trait as Trait>::fn`).
+    query fn_abi_of_instance(
+        key: ty::ParamEnvAnd<'tcx, (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>)>
+    ) -> Result<&'tcx abi::call::FnAbi<'tcx, Ty<'tcx>>, ty::layout::FnAbiError<'tcx>> {
+        desc { "computing call ABI of `{}`", key.value.0 }
+    }
+
     query dylib_dependency_formats(_: CrateNum)
                                     -> &'tcx [(CrateNum, LinkagePreference)] {
         desc { "dylib dependency formats of crate" }
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 04d8eaf7c9f80..f72f045e9079c 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1,4 +1,3 @@
-use crate::ich::StableHashingContext;
 use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use crate::mir::{GeneratorLayout, GeneratorSavedLocal};
 use crate::ty::subst::Subst;
@@ -6,7 +5,6 @@ use crate::ty::{self, subst::SubstsRef, ReprOptions, Ty, TyCtxt, TypeFoldable};
 
 use rustc_ast as ast;
 use rustc_attr as attr;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir as hir;
 use rustc_hir::lang_items::LangItem;
 use rustc_index::bit_set::BitSet;
@@ -23,10 +21,14 @@ use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec, PanicStrategy, Targ
 use std::cmp;
 use std::fmt;
 use std::iter;
-use std::mem;
 use std::num::NonZeroUsize;
 use std::ops::Bound;
 
+pub fn provide(providers: &mut ty::query::Providers) {
+    *providers =
+        ty::query::Providers { layout_of, fn_abi_of_fn_ptr, fn_abi_of_instance, ..*providers };
+}
+
 pub trait IntegerExt {
     fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>, signed: bool) -> Ty<'tcx>;
     fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer;
@@ -191,7 +193,7 @@ pub const FAT_PTR_EXTRA: usize = 1;
 /// * Cranelift stores the base-2 log of the lane count in a 4 bit integer.
 pub const MAX_SIMD_LANES: u64 = 1 << 0xF;
 
-#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable)]
+#[derive(Copy, Clone, Debug, HashStable, TyEncodable, TyDecodable)]
 pub enum LayoutError<'tcx> {
     Unknown(Ty<'tcx>),
     SizeOverflow(Ty<'tcx>),
@@ -248,10 +250,6 @@ fn layout_of<'tcx>(
     })
 }
 
-pub fn provide(providers: &mut ty::query::Providers) {
-    *providers = ty::query::Providers { layout_of, ..*providers };
-}
-
 pub struct LayoutCx<'tcx, C> {
     pub tcx: C,
     pub param_env: ty::ParamEnv<'tcx>,
@@ -2537,18 +2535,6 @@ where
     }
 }
 
-impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for LayoutError<'tcx> {
-    #[inline]
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        use crate::ty::layout::LayoutError::*;
-        mem::discriminant(self).hash_stable(hcx, hasher);
-
-        match *self {
-            Unknown(t) | SizeOverflow(t) => t.hash_stable(hcx, hasher),
-        }
-    }
-}
-
 impl<'tcx> ty::Instance<'tcx> {
     // NOTE(eddyb) this is private to avoid using it from outside of
     // `fn_abi_of_instance` - any other uses are either too high-level
@@ -2807,6 +2793,7 @@ pub fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
 }
 
 /// Error produced by attempting to compute or adjust a `FnAbi`.
+#[derive(Clone, Debug, HashStable)]
 pub enum FnAbiError<'tcx> {
     /// Error produced by a `layout_of` call, while computing `FnAbi` initially.
     Layout(LayoutError<'tcx>),
@@ -2839,9 +2826,9 @@ impl<'tcx> fmt::Display for FnAbiError<'tcx> {
 // FIXME(eddyb) maybe use something like this for an unified `fn_abi_of`, not
 // just for error handling.
 #[derive(Debug)]
-pub enum FnAbiRequest<'a, 'tcx> {
-    OfFnPtr { sig: ty::PolyFnSig<'tcx>, extra_args: &'a [Ty<'tcx>] },
-    OfInstance { instance: ty::Instance<'tcx>, extra_args: &'a [Ty<'tcx>] },
+pub enum FnAbiRequest<'tcx> {
+    OfFnPtr { sig: ty::PolyFnSig<'tcx>, extra_args: &'tcx ty::List<Ty<'tcx>> },
+    OfInstance { instance: ty::Instance<'tcx>, extra_args: &'tcx ty::List<Ty<'tcx>> },
 }
 
 /// Trait for contexts that want to be able to compute `FnAbi`s.
@@ -2855,14 +2842,14 @@ pub trait FnAbiOfHelpers<'tcx>: LayoutOfHelpers<'tcx> {
     /// `Self::FnAbiOfResult` (which does not need to be a `Result<...>`).
     ///
     /// Most `impl`s, which propagate `FnAbiError`s, should simply return `err`,
-    /// but this hook allows e.g. codegen to return only `&FnABi` from its
+    /// but this hook allows e.g. codegen to return only `&FnAbi` from its
     /// `cx.fn_abi_of_*(...)`, without any `Result<...>` around it to deal with
     /// (and any `FnAbiError`s are turned into fatal errors or ICEs).
     fn handle_fn_abi_err(
         &self,
         err: FnAbiError<'tcx>,
         span: Span,
-        fn_abi_request: FnAbiRequest<'_, 'tcx>,
+        fn_abi_request: FnAbiRequest<'tcx>,
     ) -> <Self::FnAbiOfResult as MaybeResult<&'tcx FnAbi<'tcx, Ty<'tcx>>>>::Error;
 }
 
@@ -2876,18 +2863,15 @@ pub trait FnAbiOf<'tcx>: FnAbiOfHelpers<'tcx> {
     fn fn_abi_of_fn_ptr(
         &self,
         sig: ty::PolyFnSig<'tcx>,
-        extra_args: &[Ty<'tcx>],
+        extra_args: &'tcx ty::List<Ty<'tcx>>,
     ) -> Self::FnAbiOfResult {
         // FIXME(eddyb) get a better `span` here.
         let span = self.layout_tcx_at_span();
-        let cx = LayoutCx { tcx: self.tcx().at(span), param_env: self.param_env() };
+        let tcx = self.tcx().at(span);
 
-        MaybeResult::from(
-            cx.fn_abi_new_internal(sig, extra_args, None, CodegenFnAttrFlags::empty(), false)
-                .map_err(|err| {
-                    self.handle_fn_abi_err(err, span, FnAbiRequest::OfFnPtr { sig, extra_args })
-                }),
-        )
+        MaybeResult::from(tcx.fn_abi_of_fn_ptr(self.param_env().and((sig, extra_args))).map_err(
+            |err| self.handle_fn_abi_err(err, span, FnAbiRequest::OfFnPtr { sig, extra_args }),
+        ))
     }
 
     /// Compute a `FnAbi` suitable for declaring/defining an `fn` instance, and for
@@ -2899,36 +2883,19 @@ pub trait FnAbiOf<'tcx>: FnAbiOfHelpers<'tcx> {
     fn fn_abi_of_instance(
         &self,
         instance: ty::Instance<'tcx>,
-        extra_args: &[Ty<'tcx>],
+        extra_args: &'tcx ty::List<Ty<'tcx>>,
     ) -> Self::FnAbiOfResult {
         // FIXME(eddyb) get a better `span` here.
         let span = self.layout_tcx_at_span();
-        let cx = LayoutCx { tcx: self.tcx().at(span), param_env: self.param_env() };
-
-        let sig = instance.fn_sig_for_fn_abi(cx.tcx());
-
-        let caller_location = if instance.def.requires_caller_location(cx.tcx()) {
-            Some(cx.tcx.caller_location_ty())
-        } else {
-            None
-        };
-
-        let attrs = cx.tcx.codegen_fn_attrs(instance.def_id()).flags;
+        let tcx = self.tcx().at(span);
 
         MaybeResult::from(
-            cx.fn_abi_new_internal(
-                sig,
-                extra_args,
-                caller_location,
-                attrs,
-                matches!(instance.def, ty::InstanceDef::Virtual(..)),
-            )
-            .map_err(|err| {
+            tcx.fn_abi_of_instance(self.param_env().and((instance, extra_args))).map_err(|err| {
                 // HACK(eddyb) at least for definitions of/calls to `Instance`s,
                 // we can get some kind of span even if one wasn't provided.
                 // However, we don't do this early in order to avoid calling
                 // `def_span` unconditionally (which may have a perf penalty).
-                let span = if !span.is_dummy() { span } else { cx.tcx.def_span(instance.def_id()) };
+                let span = if !span.is_dummy() { span } else { tcx.def_span(instance.def_id()) };
                 self.handle_fn_abi_err(err, span, FnAbiRequest::OfInstance { instance, extra_args })
             }),
         )
@@ -2937,10 +2904,50 @@ pub trait FnAbiOf<'tcx>: FnAbiOfHelpers<'tcx> {
 
 impl<C: FnAbiOfHelpers<'tcx>> FnAbiOf<'tcx> for C {}
 
-impl<'tcx> LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> {
+fn fn_abi_of_fn_ptr<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    query: ty::ParamEnvAnd<'tcx, (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
+) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
+    let (param_env, (sig, extra_args)) = query.into_parts();
+
+    LayoutCx { tcx, param_env }.fn_abi_new_uncached(
+        sig,
+        extra_args,
+        None,
+        CodegenFnAttrFlags::empty(),
+        false,
+    )
+}
+
+fn fn_abi_of_instance<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    query: ty::ParamEnvAnd<'tcx, (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
+) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
+    let (param_env, (instance, extra_args)) = query.into_parts();
+
+    let sig = instance.fn_sig_for_fn_abi(tcx);
+
+    let caller_location = if instance.def.requires_caller_location(tcx) {
+        Some(tcx.caller_location_ty())
+    } else {
+        None
+    };
+
+    let attrs = tcx.codegen_fn_attrs(instance.def_id()).flags;
+
+    LayoutCx { tcx, param_env }.fn_abi_new_uncached(
+        sig,
+        extra_args,
+        caller_location,
+        attrs,
+        matches!(instance.def, ty::InstanceDef::Virtual(..)),
+    )
+}
+
+impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
     // FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
     // arguments of this method, into a separate `struct`.
-    fn fn_abi_new_internal(
+    fn fn_abi_new_uncached(
         &self,
         sig: ty::PolyFnSig<'tcx>,
         extra_args: &[Ty<'tcx>],
@@ -2949,7 +2956,7 @@ impl<'tcx> LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> {
         // FIXME(eddyb) replace this with something typed, like an `enum`.
         force_thin_self_ptr: bool,
     ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
-        debug!("FnAbi::new_internal({:?}, {:?})", sig, extra_args);
+        debug!("fn_abi_new_uncached({:?}, {:?})", sig, extra_args);
 
         let sig = self.tcx.normalize_erasing_late_bound_regions(self.param_env, sig);
 
@@ -3110,7 +3117,7 @@ impl<'tcx> LayoutCx<'tcx, ty::query::TyCtxtAt<'tcx>> {
             can_unwind: fn_can_unwind(self.tcx(), codegen_fn_attr_flags, sig.abi),
         };
         self.fn_abi_adjust_for_abi(&mut fn_abi, sig.abi)?;
-        debug!("FnAbi::new_internal = {:?}", fn_abi);
+        debug!("fn_abi_new_uncached = {:?}", fn_abi);
         Ok(self.tcx.intern_fn_abi(fn_abi))
     }
 
diff --git a/compiler/rustc_middle/src/ty/query.rs b/compiler/rustc_middle/src/ty/query.rs
index 15a8888ee65ed..154b26464a804 100644
--- a/compiler/rustc_middle/src/ty/query.rs
+++ b/compiler/rustc_middle/src/ty/query.rs
@@ -48,6 +48,7 @@ use rustc_index::{bit_set::FiniteBitSet, vec::IndexVec};
 use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
 use rustc_session::utils::NativeLibKind;
 use rustc_session::Limits;
+use rustc_target::abi;
 use rustc_target::spec::PanicStrategy;
 
 use rustc_ast as ast;
diff --git a/compiler/rustc_query_impl/src/keys.rs b/compiler/rustc_query_impl/src/keys.rs
index 42e8b4023cfad..563a3cf14382c 100644
--- a/compiler/rustc_query_impl/src/keys.rs
+++ b/compiler/rustc_query_impl/src/keys.rs
@@ -449,3 +449,25 @@ impl<'tcx> Key for (ty::Predicate<'tcx>, traits::WellFormedLoc) {
         DUMMY_SP
     }
 }
+
+impl<'tcx> Key for (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
+    #[inline(always)]
+    fn query_crate_is_local(&self) -> bool {
+        true
+    }
+
+    fn default_span(&self, _: TyCtxt<'_>) -> Span {
+        DUMMY_SP
+    }
+}
+
+impl<'tcx> Key for (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>) {
+    #[inline(always)]
+    fn query_crate_is_local(&self) -> bool {
+        true
+    }
+
+    fn default_span(&self, tcx: TyCtxt<'_>) -> Span {
+        self.0.default_span(tcx)
+    }
+}
diff --git a/compiler/rustc_target/src/abi/call/mod.rs b/compiler/rustc_target/src/abi/call/mod.rs
index 6f06f2b56ada6..324278c57bf14 100644
--- a/compiler/rustc_target/src/abi/call/mod.rs
+++ b/compiler/rustc_target/src/abi/call/mod.rs
@@ -601,6 +601,7 @@ pub struct FnAbi<'a, Ty> {
 }
 
 /// Error produced by attempting to adjust a `FnAbi`, for a "foreign" ABI.
+#[derive(Clone, Debug, HashStable_Generic)]
 pub enum AdjustForForeignAbiError {
     /// Target architecture doesn't support "foreign" (i.e. non-Rust) ABIs.
     Unsupported { arch: String, abi: spec::abi::Abi },

From 8c918d7e2d973ac3d148097224e0951daba16835 Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <eddyb@lyken.rs>
Date: Thu, 9 Sep 2021 09:43:47 +0300
Subject: [PATCH 10/10] [HACK(eddyb)] arena-allocate but don't intern `FnAbi`s.

---
 compiler/rustc_middle/src/ty/context.rs | 5 -----
 compiler/rustc_middle/src/ty/layout.rs  | 2 +-
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index e803a667879a1..7cd5584c3589b 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -55,7 +55,6 @@ use rustc_span::def_id::{DefPathHash, StableCrateId};
 use rustc_span::source_map::{MultiSpan, SourceMap};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
-use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::{Layout, TargetDataLayout, VariantIdx};
 use rustc_target::spec::abi;
 
@@ -136,7 +135,6 @@ pub struct CtxtInterners<'tcx> {
     const_allocation: InternedSet<'tcx, Allocation>,
     bound_variable_kinds: InternedSet<'tcx, List<ty::BoundVariableKind>>,
     layout: InternedSet<'tcx, Layout>,
-    fn_abi: InternedSet<'tcx, FnAbi<'tcx, Ty<'tcx>>>,
 }
 
 impl<'tcx> CtxtInterners<'tcx> {
@@ -157,7 +155,6 @@ impl<'tcx> CtxtInterners<'tcx> {
             const_allocation: Default::default(),
             bound_variable_kinds: Default::default(),
             layout: Default::default(),
-            fn_abi: Default::default(),
         }
     }
 
@@ -1962,7 +1959,6 @@ impl<'tcx> TyCtxt<'tcx> {
                     self.0.interners.const_allocation.len()
                 )?;
                 writeln!(fmt, "Layout interner: #{}", self.0.interners.layout.len())?;
-                writeln!(fmt, "FnAbi interner: #{}", self.0.interners.fn_abi.len())?;
 
                 Ok(())
             }
@@ -2087,7 +2083,6 @@ direct_interners! {
     const_: mk_const(Const<'tcx>),
     const_allocation: intern_const_alloc(Allocation),
     layout: intern_layout(Layout),
-    fn_abi: intern_fn_abi(FnAbi<'tcx, Ty<'tcx>>),
 }
 
 macro_rules! slice_interners {
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index f72f045e9079c..cfbbec374a172 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -3118,7 +3118,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
         };
         self.fn_abi_adjust_for_abi(&mut fn_abi, sig.abi)?;
         debug!("fn_abi_new_uncached = {:?}", fn_abi);
-        Ok(self.tcx.intern_fn_abi(fn_abi))
+        Ok(self.tcx.arena.alloc(fn_abi))
     }
 
     fn fn_abi_adjust_for_abi(