[PATCH] D75402: [HIP] Make sure, unused hip-pinned-shadow global var is kept within device code

[Mahesha S via Phabricator via cfe-commits]

hsmhsm updated this revision to Diff 247689.
hsmhsm added a comment.

Take care review comments by hliao.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D75402/new/

https://reviews.llvm.org/D75402

Files:
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/lib/CodeGen/CodeGenModule.h
  clang/test/CodeGenCUDA/hip-pinned-shadow.cu


Index: clang/test/CodeGenCUDA/hip-pinned-shadow.cu
===================================================================
--- clang/test/CodeGenCUDA/hip-pinned-shadow.cu
+++ clang/test/CodeGenCUDA/hip-pinned-shadow.cu
@@ -4,6 +4,8 @@
 // RUN:     -emit-llvm -o - -x hip %s | FileCheck -check-prefixes=HIPDEV %s
 // RUN: %clang_cc1 -triple x86_64 -std=c++11 \
 // RUN:     -emit-llvm -o - -x hip %s | FileCheck -check-prefixes=HIPHOST %s
+// RUN: %clang_cc1 -triple amdgcn -fcuda-is-device -std=c++11 -fvisibility hidden -fapply-global-visibility-to-externs \
+// RUN:     -O3 -emit-llvm -o - -x hip %s | FileCheck -check-prefixes=HIPDEVUNSED %s
 
 struct textureReference {
   int a;
@@ -21,3 +23,5 @@
 // HIPDEV-NOT: declare{{.*}}void @_ZN7textureIfLi2ELi1EEC1Ev
 // HIPHOST:  define{{.*}}@_ZN7textureIfLi2ELi1EEC1Ev
 // HIPHOST:  call i32 @__hipRegisterVar{{.*}}@tex{{.*}}i32 0, i32 4, i32 0, i32 0)
+// HIPDEVUNSED: @tex = external addrspace(1) global %struct.texture
+// HIPDEVUNSED-NOT: declare{{.*}}void @_ZN7textureIfLi2ELi1EEC1Ev
Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -1037,7 +1037,7 @@
   void MaybeHandleStaticInExternC(const SomeDecl *D, llvm::GlobalValue *GV);
 
   /// Add a global to a list to be added to the llvm.used metadata.
-  void addUsedGlobal(llvm::GlobalValue *GV);
+  void addUsedGlobal(llvm::GlobalValue *GV, bool SkipCheck = false);
 
   /// Add a global to a list to be added to the llvm.compiler.used metadata.
   void addCompilerUsedGlobal(llvm::GlobalValue *GV);
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -1916,9 +1916,9 @@
   }
 }
 
-void CodeGenModule::addUsedGlobal(llvm::GlobalValue *GV) {
-  assert(!GV->isDeclaration() &&
-         "Only globals with definition can force usage.");
+void CodeGenModule::addUsedGlobal(llvm::GlobalValue *GV, bool SkipCheck) {
+  assert(SkipCheck || (!GV->isDeclaration() &&
+                       "Only globals with definition can force usage."));
   LLVMUsed.emplace_back(GV);
 }
 
@@ -4071,9 +4071,17 @@
     }
   }
 
-  if (!IsHIPPinnedShadowVar)
+  // HIPPinnedShadowVar should remain in the final code object irrespective of
+  // whether it is used or not within the code. Add it to used list, so that
+  // it will not get eliminated when it is unused. Also, it is an extern var
+  // within device code, and it should *not* get initialized within device code.
+  if (IsHIPPinnedShadowVar)
+    addUsedGlobal(GV, /*SkipCheck=*/true);
+  else
     GV->setInitializer(Init);
-  if (emitter) emitter->finalize(GV);
+
+  if (emitter)
+    emitter->finalize(GV);
 
   // If it is safe to mark the global 'constant', do so now.
   GV->setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&


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