[clang] [HLSL][SPIRV] Fix calling convention for call in entry function. (PR #110542)

[Steven Perron via cfe-commits]

https://github.com/s-perron created https://github.com/llvm/llvm-project/pull/110542

Fix the calling convention used for the call in the entry point
wrapper. No calling convention is currently set. It can easily use the
calling convention of the function that is being called.

Without this, there is a mismatch in the calling convention between the
call site and the callee. This is undefined behaviour.


>From 5cd884067e3e2caeacc59988a0ac31ee39b11572 Mon Sep 17 00:00:00 2001
From: Steven Perron <stevenperron at google.com>
Date: Tue, 17 Sep 2024 16:22:57 -0400
Subject: [PATCH] [HLSL][SPIRV] Fix calling convention for call in entry
 function.

Fix the calling convention used for the call in the entry point
wrapper. No calling convention is currently set. It can easily use the
calling convention of the function that is being called.

Without this, there is a mismatch in the calling convention between the
call site and the callee. This is undefined behaviour.
---
 clang/lib/CodeGen/CGHLSLRuntime.cpp                    | 2 +-
 clang/test/CodeGenHLSL/semantics/DispatchThreadID.hlsl | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
index 59d8fc830dcc8f..3237d93ca31ceb 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -415,7 +415,7 @@ void CGHLSLRuntime::emitEntryFunction(const FunctionDecl *FD,
   }
 
   CallInst *CI = B.CreateCall(FunctionCallee(Fn), Args);
-  (void)CI;
+  CI->setCallingConv(Fn->getCallingConv());
   // FIXME: Handle codegen for return type semantics.
   // See: https://github.com/llvm/llvm-project/issues/57875
   B.CreateRetVoid();
diff --git a/clang/test/CodeGenHLSL/semantics/DispatchThreadID.hlsl b/clang/test/CodeGenHLSL/semantics/DispatchThreadID.hlsl
index 59c1620334d0e3..975a7264fd3f01 100644
--- a/clang/test/CodeGenHLSL/semantics/DispatchThreadID.hlsl
+++ b/clang/test/CodeGenHLSL/semantics/DispatchThreadID.hlsl
@@ -6,7 +6,8 @@
 // CHECK:       define void @foo()
 // CHECK-DXIL:  %[[#ID:]] = call i32 @llvm.[[TARGET]].thread.id(i32 0)
 // CHECK-SPIRV: %[[#ID:]] = call i32 @llvm.[[TARGET]].thread.id(i32 0)
-// CHECK:       call void @{{.*}}foo{{.*}}(i32 %[[#ID]])
+// CHECK-DXIL:       call void @{{.*}}foo{{.*}}(i32 %[[#ID]])
+// CHECK-SPIRV:      call spir_func void @{{.*}}foo{{.*}}(i32 %[[#ID]])
 [shader("compute")]
 [numthreads(8,8,1)]
 void foo(uint Idx : SV_DispatchThreadID) {}
@@ -17,6 +18,7 @@ void foo(uint Idx : SV_DispatchThreadID) {}
 // CHECK:       %[[#ID_Y:]] = call i32 @llvm.[[TARGET]].thread.id(i32 1)
 // CHECK:       %[[#ID_XY:]] = insertelement <2 x i32> %[[#ID_X_]], i32 %[[#ID_Y]], i64 1
 // CHECK-DXIL:  call void @{{.*}}bar{{.*}}(<2 x i32> %[[#ID_XY]])
+// CHECK-SPIRV:  call spir_func void @{{.*}}bar{{.*}}(<2 x i32> %[[#ID_XY]])
 [shader("compute")]
 [numthreads(8,8,1)]
 void bar(uint2 Idx : SV_DispatchThreadID) {}