[CodeGen] Unique constant CompoundLiterals.
Our newly aggressive constant folding logic makes it possible for
CGExprConstant to see the same CompoundLiteralExpr more than once. So,
emitting a new GlobalVariable every time we see a CompoundLiteral is no
longer correct.
We had a similar issue with BlockExprs that was caught while testing
said aggressive folding, so I applied the same style of fix (see D26410)
here. If we find yet another case where this needs to happen, we should
probably refactor this so we don't have a third DenseMap+getter+setter.
As a design note: getAddrOfConstantCompoundLiteralIfEmitted is really
only intended to be called by ConstExprEmitter::EmitLValue. So,
returning a GlobalVariable* instead of a ConstantAddress costs us
effectively nothing, and saves us either a few bytes per entry in our
map or a bit of code duplication.
llvm-svn: 290661
diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 5f06ba9..1d72b4e 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -455,6 +455,10 @@
bool isTriviallyRecursive(const FunctionDecl *F);
bool shouldEmitFunction(GlobalDecl GD);
+ /// Map used to be sure we don't emit the same CompoundLiteral twice.
+ llvm::DenseMap<const CompoundLiteralExpr *, llvm::GlobalVariable *>
+ EmittedCompoundLiterals;
+
/// Map of the global blocks we've emitted, so that we don't have to re-emit
/// them if the constexpr evaluator gets aggressive.
llvm::DenseMap<const BlockExpr *, llvm::Constant *> EmittedGlobalBlocks;
@@ -824,6 +828,16 @@
/// compound literal expression.
ConstantAddress GetAddrOfConstantCompoundLiteral(const CompoundLiteralExpr*E);
+ /// If it's been emitted already, returns the GlobalVariable corresponding to
+ /// a compound literal. Otherwise, returns null.
+ llvm::GlobalVariable *
+ getAddrOfConstantCompoundLiteralIfEmitted(const CompoundLiteralExpr *E);
+
+ /// Notes that CLE's GlobalVariable is GV. Asserts that CLE isn't already
+ /// emitted.
+ void setAddrOfConstantCompoundLiteral(const CompoundLiteralExpr *CLE,
+ llvm::GlobalVariable *GV);
+
/// \brief Returns a pointer to a global variable representing a temporary
/// with static or thread storage duration.
ConstantAddress GetAddrOfGlobalTemporary(const MaterializeTemporaryExpr *E,