maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[InstCombine] Call hasNoSignedWrap instead of hasNoUnsignedWrap to get the NSW flag when handling Add in SimplifyDemandedUseBits. 

This is a typo from r311789.

This should fix PR34349.

llvm-svn: 311902
This commit is contained in:
Craig Topper 2017-08-28 18:44:28 +00:00
parent 2164a271a3
commit 3763f0e00d
2 changed files with 28 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
View File

@ -426,7 +426,7 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
return I->getOperand(1);
// Otherwise just compute the known bits of the result.
bool NSW = cast<OverflowingBinaryOperator>(I)->hasNoUnsignedWrap();
bool NSW = cast<OverflowingBinaryOperator>(I)->hasNoSignedWrap();
Known = KnownBits::computeForAddSub(I->getOpcode() == Instruction::Add,
NSW, LHSKnown, RHSKnown);
break;

27
llvm/test/Transforms/InstCombine/pr34349.ll Normal file
View File

@ -0,0 +1,27 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
;RUN: opt -instcombine -S %s | FileCheck %s
define i8 @fast_div_201(i8 %p) {
; CHECK-LABEL: @fast_div_201(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[V3:%.*]] = zext i8 [[P:%.*]] to i16
; CHECK-NEXT: [[V4:%.*]] = mul nuw nsw i16 [[V3]], 71
; CHECK-NEXT: [[V5:%.*]] = lshr i16 [[V4]], 8
; CHECK-NEXT: [[V6:%.*]] = trunc i16 [[V5]] to i8
; CHECK-NEXT: [[V7:%.*]] = sub i8 [[P]], [[V6]]
; CHECK-NEXT: [[V8:%.*]] = lshr i8 [[V7]], 1
; CHECK-NEXT: [[V13:%.*]] = add nuw i8 [[V8]], [[V6]]
; CHECK-NEXT: [[V14:%.*]] = lshr i8 [[V13]], 7
; CHECK-NEXT: ret i8 [[V14]]
;
entry:
%v3 = zext i8 %p to i16
%v4 = mul i16 %v3, 71
%v5 = lshr i16 %v4, 8
%v6 = trunc i16 %v5 to i8
%v7 = sub i8 %p, %v6
%v8 = lshr i8 %v7, 1
%v13 = add i8 %v6, %v8
%v14 = lshr i8 %v13, 7
ret i8 %v14
}