[CUDA][HIP] Externalize kernels in anonymous name space

kernels in anonymous name space needs to have unique name
to avoid duplicate symbols.

Fixes: #54560

Reviewed by: Artem Belevich

Differential Revision: https://reviews.llvm.org/D123353

(cherry picked from commit 4ea1d43)

Author: yxsamliu

clang/include/clang/AST/ASTContext.h

@@ -3279,10 +3279,10 @@ OPT_LIST(V)
   /// Return a new OMPTraitInfo object owned by this context.
   OMPTraitInfo &getNewOMPTraitInfo();
 
-  /// Whether a C++ static variable may be externalized.
+  /// Whether a C++ static variable or CUDA/HIP kernel may be externalized.
   bool mayExternalizeStaticVar(const Decl *D) const;
 
-  /// Whether a C++ static variable should be externalized.
+  /// Whether a C++ static variable or CUDA/HIP kernel should be externalized.
   bool shouldExternalizeStaticVar(const Decl *D) const;
 
   StringRef getCUIDHash() const;

clang/lib/AST/ASTContext.cpp

@@ -12263,14 +12263,16 @@ bool ASTContext::mayExternalizeStaticVar(const Decl *D) const {
                              (D->hasAttr<CUDAConstantAttr>() &&
                               !D->getAttr<CUDAConstantAttr>()->isImplicit());
   // CUDA/HIP: static managed variables need to be externalized since it is
-  // a declaration in IR, therefore cannot have internal linkage.
-  return IsStaticVar &&
-         (D->hasAttr<HIPManagedAttr>() || IsExplicitDeviceVar);
+  // a declaration in IR, therefore cannot have internal linkage. Kernels in
+  // anonymous name space needs to be externalized to avoid duplicate symbols.
+  return (IsStaticVar &&
+          (D->hasAttr<HIPManagedAttr>() || IsExplicitDeviceVar)) ||
+         (D->hasAttr<CUDAGlobalAttr>() && D->isInAnonymousNamespace());
 }
 
 bool ASTContext::shouldExternalizeStaticVar(const Decl *D) const {
   return mayExternalizeStaticVar(D) &&
-         (D->hasAttr<HIPManagedAttr>() ||
+         (D->hasAttr<HIPManagedAttr>() || D->hasAttr<CUDAGlobalAttr>() ||
           CUDADeviceVarODRUsedByHost.count(cast<VarDecl>(D)));
 }
 

clang/lib/CodeGen/CGCUDANV.cpp

@@ -287,7 +287,7 @@ std::string CGNVCUDARuntime::getDeviceSideName(const NamedDecl *ND) {
     SmallString<256> Buffer;
     llvm::raw_svector_ostream Out(Buffer);
     Out << DeviceSideName;
-    CGM.printPostfixForExternalizedStaticVar(Out);
+    CGM.printPostfixForExternalizedDecl(Out, ND);
     DeviceSideName = std::string(Out.str());
   }
   return DeviceSideName;

clang/lib/CodeGen/CodeGenModule.cpp

@@ -1367,7 +1367,7 @@ static std::string getMangledNameImpl(CodeGenModule &CGM, GlobalDecl GD,
   if (CGM.getContext().shouldExternalizeStaticVar(ND) &&
       CGM.getLangOpts().GPURelocatableDeviceCode &&
       CGM.getLangOpts().CUDAIsDevice && !CGM.getLangOpts().CUID.empty())
-    CGM.printPostfixForExternalizedStaticVar(Out);
+    CGM.printPostfixForExternalizedDecl(Out, ND);
   return std::string(Out.str());
 }
 
@@ -1455,7 +1455,7 @@ StringRef CodeGenModule::getMangledName(GlobalDecl GD) {
   // directly between host- and device-compilations, the host- and
   // device-mangling in host compilation could help catching certain ones.
   assert(!isa<FunctionDecl>(ND) || !ND->hasAttr<CUDAGlobalAttr>() ||
-         getLangOpts().CUDAIsDevice ||
+         getContext().shouldExternalizeStaticVar(ND) || getLangOpts().CUDAIsDevice ||
          (getContext().getAuxTargetInfo() &&
           (getContext().getAuxTargetInfo()->getCXXABI() !=
            getContext().getTargetInfo().getCXXABI())) ||
@@ -6645,7 +6645,8 @@ bool CodeGenModule::stopAutoInit() {
   return false;
 }
 
-void CodeGenModule::printPostfixForExternalizedStaticVar(
-    llvm::raw_ostream &OS) const {
-  OS << "__static__" << getContext().getCUIDHash();
+void CodeGenModule::printPostfixForExternalizedDecl(llvm::raw_ostream &OS,
+                                                    const Decl *D) const {
+  OS << (isa<VarDecl>(D) ? "__static__" : ".anon.")
+     << getContext().getCUIDHash();
 }

clang/lib/CodeGen/CodeGenModule.h

@@ -1447,9 +1447,10 @@ class CodeGenModule : public CodeGenTypeCache {
                                            TBAAAccessInfo *TBAAInfo = nullptr);
   bool stopAutoInit();
 
-  /// Print the postfix for externalized static variable for single source
-  /// offloading languages CUDA and HIP.
-  void printPostfixForExternalizedStaticVar(llvm::raw_ostream &OS) const;
+  /// Print the postfix for externalized static variable or kernels for single
+  /// source offloading languages CUDA and HIP.
+  void printPostfixForExternalizedDecl(llvm::raw_ostream &OS,
+                                       const Decl *D) const;
 
 private:
   llvm::Constant *GetOrCreateLLVMFunction(

clang/test/CodeGenCUDA/kernel-in-anon-ns.cu

@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -fcuda-is-device -cuid=abc \
+// RUN:   -aux-triple x86_64-unknown-linux-gnu -std=c++11 -fgpu-rdc \
+// RUN:   -emit-llvm -o - -x hip %s > %t.dev
+
+// RUN: %clang_cc1 -triple x86_64-gnu-linux -cuid=abc \
+// RUN:   -aux-triple amdgcn-amd-amdhsa -std=c++11 -fgpu-rdc \
+// RUN:   -emit-llvm -o - -x hip %s > %t.host
+
+// RUN: cat %t.dev %t.host | FileCheck %s
+
+#include "Inputs/cuda.h"
+
+// CHECK: define weak_odr {{.*}}void @[[KERN:_ZN12_GLOBAL__N_16kernelEv\.anon\.b04fd23c98500190]](
+// CHECK: @[[STR:.*]] = {{.*}} c"[[KERN]]\00"
+// CHECK: call i32 @__hipRegisterFunction({{.*}}@[[STR]]
+
+namespace {
+__global__ void kernel() {
+}
+}
+
+void test() {
+  kernel<<<1, 1>>>();
+}