[clang] Cache OpenCL types

[aeubanks]

Summary

If we call CGOpenCLRuntime::convertOpenCLSpecificType() multiple times
we should get the same type back.

[Anastasia]

Just to understand the intent - is this a performance optimization or functionality fix?

Also is there any way to test this?

clang/lib/CodeGen/CGOpenCLRuntime.h

42

Maybe it can be named CachedTys?

55

getType -> getPointerType ?

[aeubanks]

address comments

[aeubanks]

In D119011#3297305, @Anastasia wrote:

Just to understand the intent - is this a performance optimization or functionality fix?

This is a functionality fix.

Also is there any way to test this?

I came across this while working on another patch. This should be NFC with ToT clang, but was required my other patch. Since this part was easily split apart I wanted to do that.
Separately I think this makes sense in general.

[svenvh]

LGTM, thanks!

clang/lib/CodeGen/CGOpenCLRuntime.h

 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_LIB_CODEGEN_CGOPENCLRUNTIME_H
 #define LLVM_CLANG_LIB_CODEGEN_CGOPENCLRUNTIME_H
 
 #include "clang/AST/Expr.h"
 #include "clang/AST/Type.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 
 namespace clang {
 
 class BlockExpr;
 class Expr;
 class VarDecl;
 
 namespace CodeGen {
 
 class CodeGenFunction;
 class CodeGenModule;
 
 class CGOpenCLRuntime {
 protected:
   CodeGenModule &CGM;
   llvm::Type *PipeROTy;
   llvm::Type *PipeWOTy;
   llvm::PointerType *SamplerTy;
+  llvm::StringMap<llvm::PointerType *> CachedTys;
 
   /// Structure for enqueued block information.
   struct EnqueuedBlockInfo {
     llvm::Function *InvokeFunc; /// Block invoke function.
     llvm::Function *Kernel;     /// Enqueued block kernel.
     llvm::Value *BlockArg;      /// The first argument to enqueued block kernel.
   };
   /// Maps block expression to block information.
   llvm::DenseMap<const Expr *, EnqueuedBlockInfo> EnqueuedBlockMap;
 
   virtual llvm::Type *getPipeType(const PipeType *T, StringRef Name,
                                   llvm::Type *&PipeTy);
+  llvm::PointerType *getPointerType(const Type *T, StringRef Name);
 
 public:
   CGOpenCLRuntime(CodeGenModule &CGM) : CGM(CGM),
     PipeROTy(nullptr), PipeWOTy(nullptr), SamplerTy(nullptr) {}
   virtual ~CGOpenCLRuntime();
 
   /// Emit the IR required for a work-group-local variable declaration, and add
   /// an entry to CGF's LocalDeclMap for D.  The base class does this using

clang/lib/CodeGen/CGOpenCLRuntime.cpp

void CGOpenCLRuntime::EmitWorkGroupLocalVarDecl(CodeGenFunction &CGF,
                                                 const VarDecl &D) {
   return CGF.EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
 }
 
 llvm::Type *CGOpenCLRuntime::convertOpenCLSpecificType(const Type *T) {
   assert(T->isOpenCLSpecificType() &&
          "Not an OpenCL specific type!");
 
-  llvm::LLVMContext& Ctx = CGM.getLLVMContext();
-  uint32_t AddrSpc = CGM.getContext().getTargetAddressSpace(
-      CGM.getContext().getOpenCLTypeAddrSpace(T));
   switch (cast<BuiltinType>(T)->getKind()) {
   default:
     llvm_unreachable("Unexpected opencl builtin type!");
     return nullptr;
-#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
-  case BuiltinType::Id: \
-    return llvm::PointerType::get( \
-        llvm::StructType::create(Ctx, "opencl." #ImgType "_" #Suffix "_t"), \
-        AddrSpc);
+#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix)                   \
+  case BuiltinType::Id:                                                        \
+    return getPointerType(T, "opencl." #ImgType "_" #Suffix "_t");
 #include "clang/Basic/OpenCLImageTypes.def"
   case BuiltinType::OCLSampler:
     return getSamplerType(T);
   case BuiltinType::OCLEvent:
-    return llvm::PointerType::get(
-        llvm::StructType::create(Ctx, "opencl.event_t"), AddrSpc);
+    return getPointerType(T, "opencl.event_t");
   case BuiltinType::OCLClkEvent:
-    return llvm::PointerType::get(
-        llvm::StructType::create(Ctx, "opencl.clk_event_t"), AddrSpc);
+    return getPointerType(T, "opencl.clk_event_t");
   case BuiltinType::OCLQueue:
-    return llvm::PointerType::get(
-        llvm::StructType::create(Ctx, "opencl.queue_t"), AddrSpc);
+    return getPointerType(T, "opencl.queue_t");
   case BuiltinType::OCLReserveID:
-    return llvm::PointerType::get(
-        llvm::StructType::create(Ctx, "opencl.reserve_id_t"), AddrSpc);
-#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
-  case BuiltinType::Id: \
-    return llvm::PointerType::get( \
-        llvm::StructType::create(Ctx, "opencl." #ExtType), AddrSpc);
+    return getPointerType(T, "opencl.reserve_id_t");
+#define EXT_OPAQUE_TYPE(ExtType, Id, Ext)                                      \
+  case BuiltinType::Id:                                                        \
+    return getPointerType(T, "opencl." #ExtType);
 #include "clang/Basic/OpenCLExtensionTypes.def"
   }
 }
 
+llvm::PointerType *CGOpenCLRuntime::getPointerType(const Type *T,
+                                                   StringRef Name) {
+  auto I = CachedTys.find(Name);
+  if (I != CachedTys.end())
+    return I->second;
+
+  llvm::LLVMContext &Ctx = CGM.getLLVMContext();
+  uint32_t AddrSpc = CGM.getContext().getTargetAddressSpace(
+      CGM.getContext().getOpenCLTypeAddrSpace(T));
+  auto *PTy =
+      llvm::PointerType::get(llvm::StructType::create(Ctx, Name), AddrSpc);
+  CachedTys[Name] = PTy;
+  return PTy;
+}
+
 llvm::Type *CGOpenCLRuntime::getPipeType(const PipeType *T) {
   if (T->isReadOnly())
     return getPipeType(T, "opencl.pipe_ro_t", PipeROTy);
   else
     return getPipeType(T, "opencl.pipe_wo_t", PipeWOTy);
 }
 
 llvm::Type *CGOpenCLRuntime::getPipeType(const PipeType *T, StringRef Name,