CUDA: add CodeGen support for global variable address spaces.

Because in CUDA types do not have associated address spaces,
globals are declared in their "native" address space, and accessed
by bitcasting the pointer to address space 0.  This relies on address
space 0 being a unified address space.

llvm-svn: 157167

1 files changed, 21 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index f2dda5d658f..0da493ffb55 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1172,11 +1172,12 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName,
     DeferredDecls.erase(DDI);
   }
 
+  unsigned AddrSpace = GetGlobalVarAddressSpace(D, Ty->getAddressSpace());
   llvm::GlobalVariable *GV =
     new llvm::GlobalVariable(getModule(), Ty->getElementType(), false,
                              llvm::GlobalValue::ExternalLinkage,
                              0, MangledName, 0,
-                             false, Ty->getAddressSpace());
+                             false, AddrSpace);
 
   // Handle things which are present even on external declarations.
   if (D) {
@@ -1202,7 +1203,10 @@ CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName,
     GV->setThreadLocal(D->isThreadSpecified());
   }
 
-  return GV;
+  if (AddrSpace != Ty->getAddressSpace())
+    return llvm::ConstantExpr::getBitCast(GV, Ty);
+  else
+    return GV;
 }
 
 
@@ -1487,6 +1491,20 @@ CodeGenModule::MaybeEmitGlobalStdInitializerListInitializer(const VarDecl *D,
   return llvmInit;
 }
 
+unsigned CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D,
+                                                 unsigned AddrSpace) {
+  if (LangOpts.CUDA && CodeGenOpts.CUDAIsDevice) {
+    if (D->hasAttr<CUDAConstantAttr>())
+      AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_constant);
+    else if (D->hasAttr<CUDASharedAttr>())
+      AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_shared);
+    else
+      AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_device);
+  }
+
+  return AddrSpace;
+}
+
 void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
   llvm::Constant *Init = 0;
   QualType ASTTy = D->getType();
@@ -1566,7 +1584,7 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
   if (GV == 0 ||
       GV->getType()->getElementType() != InitType ||
       GV->getType()->getAddressSpace() !=
-        getContext().getTargetAddressSpace(ASTTy)) {
+       GetGlobalVarAddressSpace(D, getContext().getTargetAddressSpace(ASTTy))) {
 
     // Move the old entry aside so that we'll create a new one.
     Entry->setName(StringRef());