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CodeGen: When emitting stores for an initializer, only emit a GEP if we really need the store. 

This avoids emitting many dead GEPs for large zero-initialized arrays.

llvm-svn: 162701
This commit is contained in:
Benjamin Kramer 2012-08-27 21:35:58 +00:00
parent 71f611fbd6
commit 46cbe77b49
2 changed files with 12 additions and 7 deletions
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17
clang/lib/CodeGen/CGDecl.cpp
View File

@ -719,10 +719,11 @@ static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
dyn_cast<llvm::ConstantDataSequential>(Init)) {
for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
llvm::Constant *Elt = CDS->getElementAsConstant(i);
// Get a pointer to the element and emit it.
emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
isVolatile, Builder);
// If necessary, get a pointer to the element and emit it.
if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
isVolatile, Builder);
}
return;
}
@ -732,9 +733,11 @@ static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
// Get a pointer to the element and emit it.
emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
isVolatile, Builder);
// If necessary, get a pointer to the element and emit it.
if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
isVolatile, Builder);
}
}

2
clang/test/CodeGen/init.c
View File

@ -69,6 +69,8 @@ char test8(int X) {
// CHECK: store i8 97
// CHECK: store i8 98
// CHECK: store i8 99
// CHECK-NOT: getelementptr
// CHECK: load
}
void bar(void*);