Auto merge of #143684 - nikic:llvm-21, r=<try>

Update to LLVM 21

Depends on:
 * [x] llvm/llvm-project#147781
 * [x] llvm/llvm-project#147935
 * [x] llvm/llvm-project#139443
 * [x] llvm/llvm-project#148207
 * [x] llvm/llvm-project#148607

r? `@ghost`

Author: rust-bors[bot]

.gitmodules

@@ -24,8 +24,8 @@
 	shallow = true
 [submodule "src/llvm-project"]
 	path = src/llvm-project
-	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/20.1-2025-07-13
+	url = https://github.com/nikic/llvm-project.git
+	branch = rust-llvm-21
 	shallow = true
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book

compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs

@@ -39,6 +39,7 @@ impl OwnedTargetMachine {
         debug_info_compression: &CStr,
         use_emulated_tls: bool,
         args_cstr_buff: &[u8],
+        use_wasm_eh: bool,
     ) -> Result<Self, LlvmError<'static>> {
         assert!(args_cstr_buff.len() > 0);
         assert!(
@@ -72,6 +73,7 @@ impl OwnedTargetMachine {
                 use_emulated_tls,
                 args_cstr_buff.as_ptr() as *const c_char,
                 args_cstr_buff.len(),
+                use_wasm_eh,
             )
         };
 

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -15,6 +15,7 @@ use rustc_codegen_ssa::back::write::{
     BitcodeSection, CodegenContext, EmitObj, ModuleConfig, TargetMachineFactoryConfig,
     TargetMachineFactoryFn,
 };
+use rustc_codegen_ssa::base::wants_wasm_eh;
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen, ModuleKind};
 use rustc_data_structures::profiling::SelfProfilerRef;
@@ -285,6 +286,8 @@ pub(crate) fn target_machine_factory(
     let file_name_display_preference =
         sess.filename_display_preference(RemapPathScopeComponents::DEBUGINFO);
 
+    let use_wasm_eh = wants_wasm_eh(sess);
+
     Arc::new(move |config: TargetMachineFactoryConfig| {
         let path_to_cstring_helper = |path: Option<PathBuf>| -> CString {
             let path = path.unwrap_or_default();
@@ -321,6 +324,7 @@ pub(crate) fn target_machine_factory(
             &debuginfo_compression,
             use_emulated_tls,
             &args_cstr_buff,
+            use_wasm_eh,
         )
     })
 }

compiler/rustc_codegen_llvm/src/context.rs

@@ -206,6 +206,11 @@ pub(crate) unsafe fn create_module<'ll>(
             // LLVM 21 updated the default layout on nvptx: https://github.com/llvm/llvm-project/pull/124961
             target_data_layout = target_data_layout.replace("e-p6:32:32-i64", "e-i64");
         }
+        if sess.target.arch == "amdgpu" {
+            // LLVM 21 adds the address width for address space 8.
+            // See https://github.com/llvm/llvm-project/pull/139419
+            target_data_layout = target_data_layout.replace("p8:128:128:128:48", "p8:128:128")
+        }
     }
 
     // Ensure the data-layout values hardcoded remain the defaults.

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -2425,6 +2425,7 @@ unsafe extern "C" {
         UseEmulatedTls: bool,
         ArgsCstrBuff: *const c_char,
         ArgsCstrBuffLen: usize,
+        UseWasmEH: bool,
     ) -> *mut TargetMachine;
 
     pub(crate) fn LLVMRustDisposeTargetMachine(T: *mut TargetMachine);

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -396,7 +396,7 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     bool EmitStackSizeSection, bool RelaxELFRelocations, bool UseInitArray,
     const char *SplitDwarfFile, const char *OutputObjFile,
     const char *DebugInfoCompression, bool UseEmulatedTls,
-    const char *ArgsCstrBuff, size_t ArgsCstrBuffLen) {
+    const char *ArgsCstrBuff, size_t ArgsCstrBuffLen, bool UseWasmEH) {
 
   auto OptLevel = fromRust(RustOptLevel);
   auto RM = fromRust(RustReloc);
@@ -462,6 +462,9 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     Options.ThreadModel = ThreadModel::Single;
   }
 
+  if (UseWasmEH)
+    Options.ExceptionModel = ExceptionHandling::Wasm;
+
   Options.EmitStackSizeSection = EmitStackSizeSection;
 
   if (ArgsCstrBuff != nullptr) {

compiler/rustc_target/src/spec/targets/amdgcn_amd_amdhsa.rs

@@ -3,7 +3,7 @@ use crate::spec::{Cc, LinkerFlavor, Lld, PanicStrategy, Target, TargetMetadata,
 pub(crate) fn target() -> Target {
     Target {
         arch: "amdgpu".into(),
-        data_layout: "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128-p9:192:256:256:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9".into(),
+        data_layout: "e-p:64:64-p1:64:64-p2:32:32-p3:32:32-p4:64:64-p5:32:32-p6:32:32-p7:160:256:256:32-p8:128:128:128:48-p9:192:256:256:32-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-v2048:2048-n32:64-S32-A5-G1-ni:7:8:9".into(),
         llvm_target: "amdgcn-amd-amdhsa".into(),
         metadata: TargetMetadata {
             description: Some("AMD GPU".into()),

src/llvm-project

@@ -8,6 +8,14 @@
 //@ min-llvm-version: 21.0.0
 
 #![crate_type = "lib"]
+#![feature(no_core)]
+#![no_core]
+
+extern crate minicore;
+
+unsafe extern "C" {
+    safe fn add(x: i32, y: i32) -> i32;
+}
 
 pub fn add_one(x: i32) -> i32 {
     // CHECK-LABEL: __cfi__{{.*}}7add_one{{.*}}:
@@ -23,7 +31,7 @@ pub fn add_one(x: i32) -> i32 {
     // CHECK-NEXT:  nop
     // CHECK-NEXT:  nop
     // CHECK-NEXT:  mov ecx, 2628068948
-    x + 1
+    add(x, 1)
 }
 
 pub fn add_two(x: i32, _y: i32) -> i32 {
@@ -40,7 +48,7 @@ pub fn add_two(x: i32, _y: i32) -> i32 {
     // CHECK-NEXT:  nop
     // CHECK-NEXT:  nop
     // CHECK-NEXT:  mov edx, 2505940310
-    x + 2
+    add(x, 2)
 }
 
 pub fn do_twice(f: fn(i32) -> i32, arg: i32) -> i32 {
@@ -57,5 +65,5 @@ pub fn do_twice(f: fn(i32) -> i32, arg: i32) -> i32 {
     // CHECK-NEXT:  nop
     // CHECK-NEXT:  nop
     // CHECK-NEXT:  mov edx, 653723426
-    f(arg) + f(arg)
+    add(f(arg), f(arg))
 }

tests/assembly/sanitizer/kcfi/emit-arity-indicator.rs

@@ -2,7 +2,6 @@
 //@ assembly-output: emit-asm
 //@ compile-flags: -C target-feature=+exception-handling
 //@ compile-flags: -C panic=unwind
-//@ compile-flags: -C llvm-args=-wasm-enable-eh
 
 #![crate_type = "lib"]
 #![feature(core_intrinsics)]