Skip to content

[InstCombine] Fix regressions from canonicalizing (icmp eq/ne (X, Y), Y -> (icmp eq/ne (~X, Y), 0) #93656

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
goldsteinn wants to merge 1 commit into from
+11 −10
Closed

[InstCombine] Fix regressions from canonicalizing (icmp eq/ne (X, Y), Y -> (icmp eq/ne (~X, Y), 0) #93656

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4740,6 +4740,11 @@ static Instruction *foldICmpAndXX(ICmpInst &I, const SimplifyQuery &Q,
return new ICmpInst(Pred, IC.Builder.CreateOr(A, NotOp1),
Constant::getAllOnesValue(Op1->getType()));
// icmp (X & Y) eq/ne Y --> (~X & Y) eq/ne 0 if X is freely invertible.
// Since we may be consuming a `not` here, first check if we match
// `foldICmpWithLowBitMaskedVal` as it is a "better" user of `not`
// instructions.
if (Value *R = foldICmpWithLowBitMaskedVal(Pred, Op0, Op1, Q, IC))
return IC.replaceInstUsesWith(I, R);
if (auto *NotA = IC.getFreelyInverted(A, A->hasOneUse(), &IC.Builder))
return new ICmpInst(Pred, IC.Builder.CreateAnd(Op1, NotA),
Constant::getNullValue(Op1->getType()));
Expand Down
8 changes: 3 additions & 5 deletions llvm/test/Transforms/InstCombine/canonicalize-low-bit-mask-v2-and-icmp-eq-to-icmp-ule.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -144,7 +144,7 @@ define i1 @oneuse0(i8 %x, i8 %y) {
; CHECK-LABEL: @oneuse0(
; CHECK-NEXT: [[T0:%.*]] = shl nsw i8 -1, [[Y:%.*]]
; CHECK-NEXT: call void @use8(i8 [[T0]])
; CHECK-NEXT: [[X_HIGHBITS:%.*]] = and i8 [[T0]], [[X:%.*]]
; CHECK-NEXT: [[X_HIGHBITS:%.*]] = lshr i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: [[RET:%.*]] = icmp eq i8 [[X_HIGHBITS]], 0
; CHECK-NEXT: ret i1 [[RET]]
;
Expand All @@ -161,8 +161,7 @@ define i1 @oneuse1(i8 %x, i8 %y) {
; CHECK-NEXT: [[T0:%.*]] = shl nsw i8 -1, [[Y:%.*]]
; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
; CHECK-NEXT: call void @use8(i8 [[T1]])
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[T0]], [[X:%.*]]
; CHECK-NEXT: [[RET:%.*]] = icmp eq i8 [[TMP1]], 0
; CHECK-NEXT: [[RET:%.*]] = icmp uge i8 [[T1]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[RET]]
;
%t0 = shl i8 -1, %y
Expand Down Expand Up @@ -196,8 +195,7 @@ define i1 @oneuse3(i8 %x, i8 %y) {
; CHECK-NEXT: call void @use8(i8 [[T0]])
; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
; CHECK-NEXT: call void @use8(i8 [[T1]])
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[T0]], [[X:%.*]]
; CHECK-NEXT: [[RET:%.*]] = icmp eq i8 [[TMP1]], 0
; CHECK-NEXT: [[RET:%.*]] = icmp uge i8 [[T1]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[RET]]
;
%t0 = shl i8 -1, %y
Expand Down
8 changes: 3 additions & 5 deletions llvm/test/Transforms/InstCombine/canonicalize-low-bit-mask-v2-and-icmp-ne-to-icmp-ugt.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -144,7 +144,7 @@ define i1 @oneuse0(i8 %x, i8 %y) {
; CHECK-LABEL: @oneuse0(
; CHECK-NEXT: [[T0:%.*]] = shl nsw i8 -1, [[Y:%.*]]
; CHECK-NEXT: call void @use8(i8 [[T0]])
; CHECK-NEXT: [[X_HIGHBITS:%.*]] = and i8 [[T0]], [[X:%.*]]
; CHECK-NEXT: [[X_HIGHBITS:%.*]] = lshr i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: [[RET:%.*]] = icmp ne i8 [[X_HIGHBITS]], 0
; CHECK-NEXT: ret i1 [[RET]]
;
Expand All @@ -161,8 +161,7 @@ define i1 @oneuse1(i8 %x, i8 %y) {
; CHECK-NEXT: [[T0:%.*]] = shl nsw i8 -1, [[Y:%.*]]
; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
; CHECK-NEXT: call void @use8(i8 [[T1]])
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[T0]], [[X:%.*]]
; CHECK-NEXT: [[RET:%.*]] = icmp ne i8 [[TMP1]], 0
; CHECK-NEXT: [[RET:%.*]] = icmp ult i8 [[T1]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[RET]]
;
%t0 = shl i8 -1, %y
Expand Down Expand Up @@ -196,8 +195,7 @@ define i1 @oneuse3(i8 %x, i8 %y) {
; CHECK-NEXT: call void @use8(i8 [[T0]])
; CHECK-NEXT: [[T1:%.*]] = xor i8 [[T0]], -1
; CHECK-NEXT: call void @use8(i8 [[T1]])
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[T0]], [[X:%.*]]
; CHECK-NEXT: [[RET:%.*]] = icmp ne i8 [[TMP1]], 0
; CHECK-NEXT: [[RET:%.*]] = icmp ult i8 [[T1]], [[X:%.*]]
; CHECK-NEXT: ret i1 [[RET]]
;
%t0 = shl i8 -1, %y
Expand Down