[CUDA][HIP] Allow comdat for kernels

Two identical instantiations of a template function can be emitted by two TU's
with linkonce_odr linkage without causing duplicate symbols in linker. MSVC
also requires these symbols be in comdat sections. Linux does not require
the symbols in comdat sections to be merged by linker but by default
clang puts them in comdat sections.

If a template kernel is instantiated identically in two TU's. MSVC requires
that them to be in comdat sections, otherwise MSVC linker will diagnose them as
duplicate symbols. However, currently clang does not put instantiated template
kernels in comdat sections, which causes link error for MSVC.

This patch allows putting instantiated template kernels into comdat sections.

Reviewed by: Artem Belevich, Reid Kleckner

Differential Revision: https://reviews.llvm.org/D112492

1 files changed, 0 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index d36cff82f9dd..a4c60f0c50c2 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4308,11 +4308,6 @@ static bool shouldBeInCOMDAT(CodeGenModule &CGM, const Decl &D) {
   if (!CGM.supportsCOMDAT())
     return false;
 
-  // Do not set COMDAT attribute for CUDA/HIP stub functions to prevent
-  // them being "merged" by the COMDAT Folding linker optimization.
-  if (D.hasAttr<CUDAGlobalAttr>())
-    return false;
-
   if (D.hasAttr<SelectAnyAttr>())
     return true;