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Add constant support to object size handling and remove default

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lowering. We'll either figure it out, or not and be lowered by
SelectionDAGBuild.

Add test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94775 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher 2010-01-29 01:09:57 +00:00
parent 466f37befb
commit 949124ce0f
2 changed files with 65 additions and 9 deletions
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44
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -633,16 +633,42 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
break;
}
case Intrinsic::objectsize: {
ConstantInt *Const = cast<ConstantInt>(II->getOperand(2));
const Type *Ty = CI.getType();
const Type *ReturnTy = CI.getType();
Value *Op1 = II->getOperand(1);
// If we're a constant expr then we just return the number of bytes
// left in whatever we're indexing. Since it's constant there's no
// need for maximum or minimum bytes.
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) {
// If this isn't a GEP give up.
if (CE->getOpcode() != Instruction::GetElementPtr) return 0;
const PointerType *ObjTy =
reinterpret_cast<const PointerType*>(CE->getOperand(0)->getType());
// 0 is maximum number of bytes left, 1 is minimum number of bytes left.
// TODO: actually add these values, the current return values are "don't
// know".
if (Const->getZExtValue() == 0)
return ReplaceInstUsesWith(CI, Constant::getAllOnesValue(Ty));
else
return ReplaceInstUsesWith(CI, ConstantInt::get(Ty, 0));
if (const ArrayType *AT = dyn_cast<ArrayType>(ObjTy->getElementType())) {
// Deal with multi-dimensional arrays
const ArrayType *SAT = AT;
while ((AT = dyn_cast<ArrayType>(AT->getElementType())))
SAT = AT;
size_t numElems = SAT->getNumElements();
// We return the remaining bytes, so grab the size of an element
// in bytes.
size_t sizeofElem = SAT->getElementType()->getPrimitiveSizeInBits() / 8;
ConstantInt *Const =
cast<ConstantInt>(CE->getOperand(CE->getNumOperands() - 1));
size_t indx = Const->getZExtValue();
return ReplaceInstUsesWith(CI,
ConstantInt::get(ReturnTy,
((numElems - indx) * sizeofElem)));
}
}
// TODO: Add more Instruction types here.
}
}

30
test/Transforms/InstCombine/objsize.ll Normal file
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@ -0,0 +1,30 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
@a = common global [60 x i8] zeroinitializer, align 1 ; <[60 x i8]*>
@.str = private constant [8 x i8] c"abcdefg\00" ; <[8 x i8]*>
define i32 @foo() nounwind {
; CHECK: @foo
; CHECK-NEXT: ret i32 60
%1 = call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i1 false)
ret i32 %1
}
define i8* @bar() nounwind {
; CHECK: @bar
entry:
%retval = alloca i8*
%0 = call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i1 false)
%cmp = icmp ne i32 %0, -1
; CHECK: br i1 true
br i1 %cmp, label %cond.true, label %cond.false
cond.true:
%1 = load i8** %retval;
ret i8* %1;
cond.false:
%2 = load i8** %retval;
ret i8* %2;
}
declare i32 @llvm.objectsize.i32(i8*, i1) nounwind readonly