[SYCL] Cherry-pick llvm-spirv patch (#7930)

I want to use this immediately for a bugfix. It's self contained and
shouldn't affect anthing else

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@2439639

Signed-off-by: Sarnie, Nick <[email protected]>

Author: sarnex

llvm-spirv/lib/SPIRV/SPIRVWriter.cpp

@@ -904,6 +904,8 @@ SPIRVFunction *LLVMToSPIRVBase::transFunctionDecl(Function *F) {
 
   transFPGAFunctionMetadata(BF, F);
 
+  transFunctionMetadataAsUserSemanticDecoration(BF, F);
+
   SPIRVDBG(dbgs() << "[transFunction] " << *F << " => ";
            spvdbgs() << *BF << '\n';)
   return BF;
@@ -1048,6 +1050,29 @@ void LLVMToSPIRVBase::transFPGAFunctionMetadata(SPIRVFunction *BF,
     transMetadataDecorations(FDecoMD, BF);
 }
 
+void LLVMToSPIRVBase::transFunctionMetadataAsUserSemanticDecoration(
+    SPIRVFunction *BF, Function *F) {
+  if (auto *RegisterAllocModeMD = F->getMetadata("RegisterAllocMode")) {
+    // TODO: Once the design for per-kernel register size allocation is
+    // finalized, we will need to move away from UserSemantic and introduce an
+    // extension
+    int RegisterAllocNodeMDOp = getMDOperandAsInt(RegisterAllocModeMD, 0);
+    // The current RegisterAllocMode metadata format is as follows
+    // AUTO - 0
+    // SMALL - 1
+    // LARGE - 2
+    // DEFAULT - 3
+    // Currently we only support SMALL and LARGE
+    if (RegisterAllocNodeMDOp == 1 || RegisterAllocNodeMDOp == 2) {
+      // 4 threads per eu means large grf mode, and 8 threads per eu
+      // means small grf mode
+      std::string NumThreads = RegisterAllocNodeMDOp == 2 ? "4" : "8";
+      BF->addDecorate(new SPIRVDecorateUserSemanticAttr(
+          BF, "num-thread-per-eu " + NumThreads));
+    }
+  }
+}
+
 SPIRVValue *LLVMToSPIRVBase::transConstantUse(Constant *C) {
   // Constant expressions expect their pointer types to be i8* in opaque pointer
   // mode, but the value may have a different "natural" type. If that is the

llvm-spirv/lib/SPIRV/SPIRVWriter.h

@@ -122,6 +122,8 @@ class LLVMToSPIRVBase : protected BuiltinCallHelper {
   SPIRVFunction *transFunctionDecl(Function *F);
   void transVectorComputeMetadata(Function *F);
   void transFPGAFunctionMetadata(SPIRVFunction *BF, Function *F);
+  void transFunctionMetadataAsUserSemanticDecoration(SPIRVFunction *BF,
+                                                     Function *F);
   bool transGlobalVariables();
 
   Op transBoolOpCode(SPIRVValue *Opn, Op OC);

llvm-spirv/test/transcoding/registerallocmode.ll

@@ -0,0 +1,72 @@
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv -spirv-text %t.bc -o - | FileCheck %s --check-prefix=CHECK-SPIRV
+; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: spirv-val %t.spv
+; RUN: llvm-spirv -r -emit-opaque-pointers %t.spv -o - | llvm-dis -o - | FileCheck %s --check-prefix=CHECK-LLVM
+
+; CHECK-SPIRV: 8 Decorate 4 UserSemantic "num-thread-per-eu 4"
+; CHECK-SPIRV: 8 Decorate 6 UserSemantic "num-thread-per-eu 8"
+; CHECK-SPIRV-NOT: 8 Decorate 8
+; CHECK-SPIRV-NOT: 8 Decorate 10
+; CHECK-SPIRV-NOT: 8 Decorate 12
+
+; CHECK-LLVM: @[[FLAG0:[0-9]+]] = private unnamed_addr constant [20 x i8] c"num-thread-per-eu 4\00", section "llvm.metadata"
+; CHECK-LLVM: @[[FLAG1:[0-9]+]] = private unnamed_addr constant [20 x i8] c"num-thread-per-eu 8\00", section "llvm.metadata"
+
+; CHECK-LLVM: @llvm.global.annotations = appending global [2 x { ptr, ptr, ptr, i32, ptr }] [{ ptr, ptr, ptr, i32, ptr } { ptr @main_l3, ptr @[[FLAG0]], ptr undef, i32 undef, ptr undef }, { ptr, ptr, ptr, i32, ptr } { ptr @main_l6, ptr @[[FLAG1]], ptr undef, i32 undef, ptr undef }], section "llvm.metadata"
+
+target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
+target triple = "spir64"
+
+; Function Attrs: noinline nounwind optnone
+define weak dso_local spir_kernel void @main_l3() #0 !RegisterAllocMode !10 {
+newFuncRoot:
+  ret void
+}
+
+; Function Attrs: noinline nounwind optnone
+define weak dso_local spir_kernel void @main_l6() #0 !RegisterAllocMode !11 {
+newFuncRoot:
+  ret void
+}
+
+; Function Attrs: noinline nounwind optnone
+define weak dso_local spir_kernel void @main_l9() #0 !RegisterAllocMode !12 {
+newFuncRoot:
+  ret void
+}
+
+; Function Attrs: noinline nounwind optnone
+define weak dso_local spir_kernel void @main_l13() #0 !RegisterAllocMode !13 {
+newFuncRoot:
+  ret void
+}
+
+; Function Attrs: noinline nounwind optnone
+define weak dso_local spir_kernel void @main_l19() #0 {
+newFuncRoot:
+  ret void
+}
+
+attributes #0 = { noinline nounwind optnone }
+
+
+!opencl.compiler.options = !{!0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0, !0}
+!spirv.Source = !{!2, !3, !3, !3, !3, !3, !2, !3, !2, !2, !2, !2, !2, !2, !2, !2, !2, !2, !2, !2, !2, !2}
+!llvm.module.flags = !{!4, !5, !6, !7, !8}
+!spirv.MemoryModel = !{!9, !9, !9, !9, !9, !9}
+!spirv.ExecutionMode = !{}
+
+!0 = !{}
+!2 = !{i32 4, i32 200000}
+!3 = !{i32 3, i32 200000}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 7, !"openmp", i32 50}
+!6 = !{i32 7, !"openmp-device", i32 50}
+!7 = !{i32 8, !"PIC Level", i32 2}
+!8 = !{i32 7, !"frame-pointer", i32 2}
+!9 = !{i32 2, i32 2}
+!10 = !{i32 2}
+!11 = !{i32 1}
+!12 = !{i32 0}
+!13 = !{i32 3}