Extract IRGen's constant-emitter into its own helper class and clean up

the interface.

The ultimate goal here is to make it easier to do some more interesting
things in constant emission, like emit constant initializers that have
ignorable side-effects, or doing the majority of an initialization
in-place and then patching up the last few things with calls.  But for
now this is mostly just a refactoring.

llvm-svn: 310964

1 files changed, 16 insertions, 5 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index fe45d16dc2d..c726d90f2e3 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -24,6 +24,7 @@
 #include "CodeGenFunction.h"
 #include "CodeGenPGO.h"
 #include "CodeGenTBAA.h"
+#include "ConstantEmitter.h"
 #include "CoverageMappingGen.h"
 #include "TargetInfo.h"
 #include "clang/AST/ASTContext.h"
@@ -2686,6 +2687,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
   const VarDecl *InitDecl;
   const Expr *InitExpr = D->getAnyInitializer(InitDecl);
 
+  Optional<ConstantEmitter> emitter;
+
   // CUDA E.2.4.1 "__shared__ variables cannot have an initialization
   // as part of their declaration."  Sema has already checked for
   // error cases, so we just need to set Init to UndefValue.
@@ -2706,7 +2709,8 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
     Init = EmitNullConstant(D->getType());
   } else {
     initializedGlobalDecl = GlobalDecl(D);
-    Init = EmitConstantInit(*InitDecl);
+    emitter.emplace(*this);
+    Init = emitter->tryEmitForInitializer(*InitDecl);
 
     if (!Init) {
       QualType T = InitExpr->getType();
@@ -2819,7 +2823,9 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
         Linkage = llvm::GlobalValue::InternalLinkage;
     }
   }
+
   GV->setInitializer(Init);
+  if (emitter) emitter->finalize(GV);
 
   // If it is safe to mark the global 'constant', do so now.
   GV->setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&
@@ -3735,12 +3741,18 @@ ConstantAddress CodeGenModule::GetAddrOfGlobalTemporary(
       !EvalResult.hasSideEffects())
     Value = &EvalResult.Val;
 
+  unsigned AddrSpace =
+      VD ? GetGlobalVarAddressSpace(VD) : MaterializedType.getAddressSpace();
+
+  Optional<ConstantEmitter> emitter;
   llvm::Constant *InitialValue = nullptr;
   bool Constant = false;
   llvm::Type *Type;
   if (Value) {
     // The temporary has a constant initializer, use it.
-    InitialValue = EmitConstantValue(*Value, MaterializedType, nullptr);
+    emitter.emplace(*this);
+    InitialValue = emitter->emitForInitializer(*Value, AddrSpace,
+                                               MaterializedType);
     Constant = isTypeConstant(MaterializedType, /*ExcludeCtor*/Value);
     Type = InitialValue->getType();
   } else {
@@ -3765,12 +3777,11 @@ ConstantAddress CodeGenModule::GetAddrOfGlobalTemporary(
       Linkage = llvm::GlobalVariable::InternalLinkage;
     }
   }
-  unsigned AddrSpace =
-      VD ? GetGlobalVarAddressSpace(VD) : MaterializedType.getAddressSpace();
   auto TargetAS = getContext().getTargetAddressSpace(AddrSpace);
   auto *GV = new llvm::GlobalVariable(
       getModule(), Type, Constant, Linkage, InitialValue, Name.c_str(),
       /*InsertBefore=*/nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS);
+  if (emitter) emitter->finalize(GV);
   setGlobalVisibility(GV, VD);
   GV->setAlignment(Align.getQuantity());
   if (supportsCOMDAT() && GV->isWeakForLinker())
@@ -4535,7 +4546,7 @@ llvm::SanitizerStatReport &CodeGenModule::getSanStats() {
 llvm::Value *
 CodeGenModule::createOpenCLIntToSamplerConversion(const Expr *E,
                                                   CodeGenFunction &CGF) {
-  llvm::Constant *C = EmitConstantExpr(E, E->getType(), &CGF);
+  llvm::Constant *C = ConstantEmitter(CGF).emitAbstract(E, E->getType());
   auto SamplerT = getOpenCLRuntime().getSamplerType(E->getType().getTypePtr());
   auto FTy = llvm::FunctionType::get(SamplerT, {C->getType()}, false);
   return CGF.Builder.CreateCall(CreateRuntimeFunction(FTy,