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getSExtValue() doesn't work for ConstantInts with bitwidth > 64 bits. Use all 

APInt calls instead.

This fixes PR3144.

llvm-svn: 60288
This commit is contained in:
Bill Wendling 2008-11-30 12:38:24 +00:00
parent 09bc610945
commit 2d2e7861b5
2 changed files with 33 additions and 5 deletions
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10
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -2957,21 +2957,21 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
return BinaryOperator::CreateNeg(Op0);
ConstantInt *RHSNeg = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
APInt RHSNegAPI(RHSNeg->getBitWidth(), RHSNeg->getSExtValue(), true);
APInt RHSNegAPI(RHSNeg->getValue());
APInt NegOne = -APInt(RHSNeg->getBitWidth(), 1, true);
APInt TwoToExp(RHSNeg->getBitWidth(), 1 << (RHSNeg->getBitWidth() - 1));
// -X/C -> X/-C, if and only if negation doesn't overflow.
if ((RHS->getSExtValue() < 0 && RHSNegAPI.slt(TwoToExp - 1)) ||
(RHS->getSExtValue() > 0 && RHSNegAPI.sgt(TwoToExp * NegOne))) {
if ((RHS->getValue().isNegative() && RHSNegAPI.slt(TwoToExp - 1)) ||
(RHS->getValue().isNonNegative() && RHSNegAPI.sgt(TwoToExp * NegOne))) {
if (Value *LHSNeg = dyn_castNegVal(Op0)) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(LHSNeg)) {
ConstantInt *CINeg = cast<ConstantInt>(ConstantExpr::getNeg(CI));
APInt CINegAPI(CINeg->getBitWidth(), CINeg->getSExtValue(), true);
if ((CI->getSExtValue() < 0 && CINegAPI.slt(TwoToExp - 1)) ||
(CI->getSExtValue() > 0 && CINegAPI.sgt(TwoToExp * NegOne)))
if ((CI->getValue().isNegative() && CINegAPI.slt(TwoToExp - 1)) ||
(CI->getValue().isNonNegative() && CINegAPI.sgt(TwoToExp*NegOne)))
return BinaryOperator::CreateSDiv(LHSNeg,
ConstantExpr::getNeg(RHS));
}

28
llvm/test/Transforms/InstCombine/sdiv-2.ll Normal file
View File

@ -0,0 +1,28 @@
; RUN: llvm-as < %s | opt -instcombine -disable-output
; PR3144
define fastcc i32 @func(i32 %length) nounwind {
entry:
%0 = icmp ne i32 %length, -1 ; <i1> [#uses=1]
%iftmp.13.0 = select i1 %0, i128 0, i128 200000000 ; <i128> [#uses=2]
%1 = sdiv i128 %iftmp.13.0, 10 ; <i128> [#uses=1]
br label %bb5
bb5: ; preds = %bb8, %entry
%v.0 = phi i128 [ 0, %entry ], [ %6, %bb8 ] ; <i128> [#uses=2]
%2 = icmp sgt i128 %v.0, %1 ; <i1> [#uses=1]
br i1 %2, label %overflow, label %bb7
bb7: ; preds = %bb5
%3 = mul i128 %v.0, 10 ; <i128> [#uses=2]
%4 = sub i128 %iftmp.13.0, 0 ; <i128> [#uses=1]
%5 = icmp slt i128 %4, %3 ; <i1> [#uses=1]
br i1 %5, label %overflow, label %bb8
bb8: ; preds = %bb7
%6 = add i128 0, %3 ; <i128> [#uses=1]
br label %bb5
overflow: ; preds = %bb7, %bb5
ret i32 1
}