constexpr irgen: Add irgen support for APValue::Struct, APValue::Union,

APValue::Array and APValue::MemberPointer. All APValue values can now be emitted
as constants.

Add new CGCXXABI entry point for emitting an APValue MemberPointer. The other
entrypoints dealing with constant member pointers are no longer necessary and
will be removed in a later change.

Switch codegen from using EvaluateAsRValue/EvaluateAsLValue to
VarDecl::evaluateValue. This performs caching and deals with the nasty cases in
C++11 where a non-const object's initializer can refer indirectly to
previously-initialized fields within the same object.

Building the intermediate APValue object incurs a measurable performance hit on
pathological testcases with huge initializer lists, so we continue to build IR
directly from the Expr nodes for array and record types outside of C++11.

llvm-svn: 148178

1 files changed, 8 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 8fc43442018..e6ecb6a88bc 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -215,6 +215,7 @@ static bool isSafeForCXXConstantCapture(QualType type) {
 /// acceptable because we make no promises about address stability of
 /// captured variables.
 static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
+                                            CodeGenFunction *CGF,
                                             const VarDecl *var) {
   QualType type = var->getType();
 
@@ -235,7 +236,7 @@ static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
   const Expr *init = var->getInit();
   if (!init) return 0;
 
-  return CGM.EmitConstantExpr(init, var->getType());
+  return CGM.EmitConstantInit(*var, CGF);
 }
 
 /// Get the low bit of a nonzero character count.  This is the
@@ -278,7 +279,8 @@ static void initializeForBlockHeader(CodeGenModule &CGM, CGBlockInfo &info,
 
 /// Compute the layout of the given block.  Attempts to lay the block
 /// out with minimal space requirements.
-static void computeBlockInfo(CodeGenModule &CGM, CGBlockInfo &info) {
+static void computeBlockInfo(CodeGenModule &CGM, CodeGenFunction *CGF,
+                             CGBlockInfo &info) {
   ASTContext &C = CGM.getContext();
   const BlockDecl *block = info.getBlockDecl();
 
@@ -342,7 +344,7 @@ static void computeBlockInfo(CodeGenModule &CGM, CGBlockInfo &info) {
 
     // Otherwise, build a layout chunk with the size and alignment of
     // the declaration.
-    if (llvm::Constant *constant = tryCaptureAsConstant(CGM, variable)) {
+    if (llvm::Constant *constant = tryCaptureAsConstant(CGM, CGF, variable)) {
       info.Captures[variable] = CGBlockInfo::Capture::makeConstant(constant);
       continue;
     }
@@ -497,7 +499,7 @@ static void enterBlockScope(CodeGenFunction &CGF, BlockDecl *block) {
 
   // Compute information about the layout, etc., of this block,
   // pushing cleanups as necessary.
-  computeBlockInfo(CGF.CGM, blockInfo);
+  computeBlockInfo(CGF.CGM, &CGF, blockInfo);
 
   // Nothing else to do if it can be global.
   if (blockInfo.CanBeGlobal) return;
@@ -604,7 +606,7 @@ llvm::Value *CodeGenFunction::EmitBlockLiteral(const BlockExpr *blockExpr) {
   // layout for it.
   if (!blockExpr->getBlockDecl()->hasCaptures()) {
     CGBlockInfo blockInfo(blockExpr->getBlockDecl(), CurFn->getName());
-    computeBlockInfo(CGM, blockInfo);
+    computeBlockInfo(CGM, this, blockInfo);
     blockInfo.BlockExpression = blockExpr;
     return EmitBlockLiteral(blockInfo);
   }
@@ -911,7 +913,7 @@ CodeGenModule::GetAddrOfGlobalBlock(const BlockExpr *blockExpr,
   blockInfo.BlockExpression = blockExpr;
 
   // Compute information about the layout, etc., of this block.
-  computeBlockInfo(*this, blockInfo);
+  computeBlockInfo(*this, 0, blockInfo);
 
   // Using that metadata, generate the actual block function.
   llvm::Constant *blockFn;