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Add ConstantExpr handling to Intrinsic::objectsize lowering.

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Update testcase accordingly now that we can optimize another
section.

llvm-svn: 95846
This commit is contained in:
Eric Christopher 2010-02-11 01:48:54 +00:00
parent f4f1901ec8
commit 9516309f55
2 changed files with 27 additions and 3 deletions
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27
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -308,9 +308,14 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
Value *Op1 = II->getOperand(1);
bool Min = (cast<ConstantInt>(II->getOperand(2))->getZExtValue() == 1);
// We need target data for just about everything so depend on it.
if (!TD) break;
// Get to the real allocated thing and offset as fast as possible.
Op1 = Op1->stripPointerCasts();
// If we've stripped down to a single global variable that we
// can know the size of then just return that.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op1)) {
if (GV->hasDefinitiveInitializer()) {
Constant *C = GV->getInitializer();
@ -320,7 +325,27 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
return ReplaceInstUsesWith(CI, RetVal);
}
}
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) {
// Only handle constant GEPs here.
if (CE->getOpcode() != Instruction::GetElementPtr) break;
GEPOperator *GEP = cast<GEPOperator>(CE);
// Get what we're pointing to and its size.
const PointerType *PT =
cast<PointerType>(GEP->getPointerOperand()->getType());
size_t Size = TD->getTypeAllocSize(PT->getElementType());
// Get the current byte offset into the thing.
SmallVector<Value*, 8> Ops(CE->op_begin()+1, CE->op_end());
size_t Offset = TD->getIndexedOffset(PT, &Ops[0], Ops.size());
assert(Size >= Offset);
Constant *RetVal = ConstantInt::get(ReturnTy, Size-Offset);
return ReplaceInstUsesWith(CI, RetVal);
}
}
case Intrinsic::bswap:
// bswap(bswap(x)) -> x

3
test/Transforms/InstCombine/objsize.ll
View File

@ -31,10 +31,9 @@ cond.false:
ret i8* %2;
}
; FIXME: Should be ret i32 0
define i32 @f() nounwind {
; CHECK: @f
; CHECK-NEXT: llvm.objectsize.i32
; CHECK-NEXT: ret i32 0
%1 = call i32 @llvm.objectsize.i32(i8* getelementptr ([60 x i8]* @a, i32 1, i32 0), i1 false)
ret i32 %1
}