[llvm] r354467 - [InstSimplify] use any-zero matcher for fcmp folds
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 20 06:34:01 PST 2019
Author: spatel
Date: Wed Feb 20 06:34:00 2019
New Revision: 354467
URL: http://llvm.org/viewvc/llvm-project?rev=354467&view=rev
Log:
[InstSimplify] use any-zero matcher for fcmp folds
The m_APFloat matcher does not work with anything but strict
splat vector constants, so we could miss these folds and then
trigger an assertion in instcombine:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13201
The previous attempt at this in rL354406 had a logic bug that
actually triggered a regression test failure, but I failed to
notice it the first time.
Modified:
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll
Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=354467&r1=354466&r2=354467&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Wed Feb 20 06:34:00 2019
@@ -3648,6 +3648,8 @@ static Value *SimplifyFCmpInst(unsigned
}
// Handle fcmp with constant RHS.
+ // TODO: Use match with a specific FP value, so these work with vectors with
+ // undef lanes.
const APFloat *C;
if (match(RHS, m_APFloat(C))) {
// Check whether the constant is an infinity.
@@ -3676,28 +3678,7 @@ static Value *SimplifyFCmpInst(unsigned
}
}
}
- if (C->isZero()) {
- switch (Pred) {
- case FCmpInst::FCMP_OGE:
- if (FMF.noNaNs() && CannotBeOrderedLessThanZero(LHS, Q.TLI))
- return getTrue(RetTy);
- break;
- case FCmpInst::FCMP_UGE:
- if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
- return getTrue(RetTy);
- break;
- case FCmpInst::FCMP_ULT:
- if (FMF.noNaNs() && CannotBeOrderedLessThanZero(LHS, Q.TLI))
- return getFalse(RetTy);
- break;
- case FCmpInst::FCMP_OLT:
- if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
- return getFalse(RetTy);
- break;
- default:
- break;
- }
- } else if (C->isNegative()) {
+ if (C->isNegative() && !C->isNegZero()) {
assert(!C->isNaN() && "Unexpected NaN constant!");
// TODO: We can catch more cases by using a range check rather than
// relying on CannotBeOrderedLessThanZero.
@@ -3721,6 +3702,28 @@ static Value *SimplifyFCmpInst(unsigned
}
}
}
+ if (match(RHS, m_AnyZeroFP())) {
+ switch (Pred) {
+ case FCmpInst::FCMP_OGE:
+ if (FMF.noNaNs() && CannotBeOrderedLessThanZero(LHS, Q.TLI))
+ return getTrue(RetTy);
+ break;
+ case FCmpInst::FCMP_UGE:
+ if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
+ return getTrue(RetTy);
+ break;
+ case FCmpInst::FCMP_ULT:
+ if (FMF.noNaNs() && CannotBeOrderedLessThanZero(LHS, Q.TLI))
+ return getFalse(RetTy);
+ break;
+ case FCmpInst::FCMP_OLT:
+ if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
+ return getFalse(RetTy);
+ break;
+ default:
+ break;
+ }
+ }
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
Modified: llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll?rev=354467&r1=354466&r2=354467&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll Wed Feb 20 06:34:00 2019
@@ -399,9 +399,7 @@ define <2 x i1> @fabs_is_not_negative_po
define <2 x i1> @fabs_is_not_negative_anyzero(<2 x float> %V) {
; CHECK-LABEL: @fabs_is_not_negative_anyzero(
-; CHECK-NEXT: [[ABS:%.*]] = call <2 x float> @llvm.fabs.v2f32(<2 x float> [[V:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = fcmp olt <2 x float> [[ABS]], <float 0.000000e+00, float -0.000000e+00>
-; CHECK-NEXT: ret <2 x i1> [[CMP]]
+; CHECK-NEXT: ret <2 x i1> zeroinitializer
;
%abs = call <2 x float> @llvm.fabs.v2f32(<2 x float> %V)
%cmp = fcmp olt <2 x float> %abs, <float 0.0, float -0.0>
@@ -410,9 +408,7 @@ define <2 x i1> @fabs_is_not_negative_an
define <3 x i1> @fabs_is_not_negative_negzero_undef(<3 x float> %V) {
; CHECK-LABEL: @fabs_is_not_negative_negzero_undef(
-; CHECK-NEXT: [[ABS:%.*]] = call <3 x float> @llvm.fabs.v3f32(<3 x float> [[V:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = fcmp olt <3 x float> [[ABS]], <float -0.000000e+00, float -0.000000e+00, float undef>
-; CHECK-NEXT: ret <3 x i1> [[CMP]]
+; CHECK-NEXT: ret <3 x i1> zeroinitializer
;
%abs = call <3 x float> @llvm.fabs.v3f32(<3 x float> %V)
%cmp = fcmp olt <3 x float> %abs, <float -0.0, float -0.0, float undef>
@@ -421,9 +417,7 @@ define <3 x i1> @fabs_is_not_negative_ne
define <3 x i1> @fabs_is_not_negative_poszero_undef(<3 x float> %V) {
; CHECK-LABEL: @fabs_is_not_negative_poszero_undef(
-; CHECK-NEXT: [[ABS:%.*]] = call <3 x float> @llvm.fabs.v3f32(<3 x float> [[V:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = fcmp olt <3 x float> [[ABS]], <float 0.000000e+00, float 0.000000e+00, float undef>
-; CHECK-NEXT: ret <3 x i1> [[CMP]]
+; CHECK-NEXT: ret <3 x i1> zeroinitializer
;
%abs = call <3 x float> @llvm.fabs.v3f32(<3 x float> %V)
%cmp = fcmp olt <3 x float> %abs, <float 0.0, float 0.0, float undef>
@@ -432,9 +426,7 @@ define <3 x i1> @fabs_is_not_negative_po
define <3 x i1> @fabs_is_not_negative_anyzero_undef(<3 x float> %V) {
; CHECK-LABEL: @fabs_is_not_negative_anyzero_undef(
-; CHECK-NEXT: [[ABS:%.*]] = call <3 x float> @llvm.fabs.v3f32(<3 x float> [[V:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = fcmp olt <3 x float> [[ABS]], <float 0.000000e+00, float -0.000000e+00, float undef>
-; CHECK-NEXT: ret <3 x i1> [[CMP]]
+; CHECK-NEXT: ret <3 x i1> zeroinitializer
;
%abs = call <3 x float> @llvm.fabs.v3f32(<3 x float> %V)
%cmp = fcmp olt <3 x float> %abs, <float 0.0, float -0.0, float undef>
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