https://github.com/AlexVlx created
https://github.com/llvm/llvm-project/pull/152023
Client apps can (and in the case of the MSVC STL do) set cdecl explicitly on
`new` / `delete` implementations. On the other hand, Clang generates implicit
decls with the target's default CC. This is problematic for SPIR-V, since the
default there is spir_function, which is not compatible. Since we cannot change
pre-existing headers / implementations, this patch sets the CC to C for the
implicit host-side decls, when compiling for device, to prevent the conflict.
This is fine because the host-side overloards do not get emitted on device.
>From e33787e50ac261d09aa9bcc7b9e25b162abb00d6 Mon Sep 17 00:00:00 2001
From: Alex Voicu <alexandru.vo...@amd.com>
Date: Mon, 4 Aug 2025 21:08:56 +0100
Subject: [PATCH] Prevent spurious CC clashes.
---
clang/lib/Sema/SemaExprCXX.cpp | 7 +++++
...v-implicit-alloc-function-calling-conv.hip | 26 +++++++++++++++++++
2 files changed, 33 insertions(+)
create mode 100644
clang/test/SemaHIP/amdgcnspirv-implicit-alloc-function-calling-conv.hip
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 0edfd6015cbd9..5b9cd65c52099 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -3497,6 +3497,13 @@ void
Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
}
auto CreateAllocationFunctionDecl = [&](Attr *ExtraAttr) {
+ // The MSVC STL has explicit cdecl on its (host-side) allocation function
+ // specializations for the allocation, so in order to prevent a CC clash
+ // we set cdecl on the host-side implicit decls, knowing these do not get
+ // emitted when compiling for device.
+ if (getLangOpts().CUDAIsDevice && ExtraAttr && isa<CUDAHostAttr>(ExtraAttr)
+ && Context.getTargetInfo().getTriple().isSPIRV())
+ EPI.ExtInfo = EPI.ExtInfo.withCallingConv(CallingConv::CC_C);
QualType FnType = Context.getFunctionType(Return, Params, EPI);
FunctionDecl *Alloc = FunctionDecl::Create(
Context, GlobalCtx, SourceLocation(), SourceLocation(), Name, FnType,
diff --git
a/clang/test/SemaHIP/amdgcnspirv-implicit-alloc-function-calling-conv.hip
b/clang/test/SemaHIP/amdgcnspirv-implicit-alloc-function-calling-conv.hip
new file mode 100644
index 0000000000000..7e87a904054ce
--- /dev/null
+++ b/clang/test/SemaHIP/amdgcnspirv-implicit-alloc-function-calling-conv.hip
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 %s -fcuda-is-device -std=c++17 -triple spirv32 -verify
+// RUN: %clang_cc1 %s -fcuda-is-device -std=c++17 -triple spirv64 -verify
+// RUN: %clang_cc1 %s -fcuda-is-device -std=c++17 -triple spirv64-amd-amdhsa
-verify
+
+// expected-no-diagnostics
+
+namespace std
+{
+ enum class align_val_t : __SIZE_TYPE__ {};
+ struct nothrow_t { explicit nothrow_t() = default; };
+ extern nothrow_t const nothrow;
+}
+
+void* __attribute__((cdecl)) operator new(__SIZE_TYPE__);
+void* __attribute__((cdecl)) operator new[](__SIZE_TYPE__);
+void* __attribute__((cdecl)) operator new(__SIZE_TYPE__, ::std::align_val_t);
+void* __attribute__((cdecl)) operator new[](__SIZE_TYPE__, ::std::align_val_t);
+
+void __attribute__((cdecl)) operator delete(void*) noexcept;
+void __attribute__((cdecl)) operator delete[](void*) noexcept;
+void __attribute__((cdecl)) operator delete(void*, __SIZE_TYPE__) noexcept;
+void __attribute__((cdecl)) operator delete[](void*, __SIZE_TYPE__) noexcept;
+void __attribute__((cdecl)) operator delete(void*, ::std::align_val_t)
noexcept;
+void __attribute__((cdecl)) operator delete[](void*, ::std::align_val_t)
noexcept;
+void __attribute__((cdecl)) operator delete(void*, __SIZE_TYPE__,
::std::align_val_t) noexcept;
+void __attribute__((cdecl)) operator delete[](void*, __SIZE_TYPE__,
::std::align_val_t) noexcept;
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