[llvm] r362909 - [InstCombine] change canonicalization to fabs() to use FMF on fneg
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 9 09:22:01 PDT 2019
Author: spatel
Date: Sun Jun 9 09:22:01 2019
New Revision: 362909
URL: http://llvm.org/viewvc/llvm-project?rev=362909&view=rev
Log:
[InstCombine] change canonicalization to fabs() to use FMF on fneg
This isn't the ideal fix (use FMF on the select), but it's still an
improvement until we have better FMF propagation to selects and other
FP math operators.
I don't think there's much risk of regression from this change by
not including the FMF on the fcmp any more. The nsz/nnan FMF
should be the same on the fcmp and the fneg (fsub) because they
have the same operand.
This works around the most glaring FMF logical inconsistency cited
in PR38086:
https://bugs.llvm.org/show_bug.cgi?id=38086
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
llvm/trunk/test/Transforms/InstCombine/fabs.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp?rev=362909&r1=362908&r2=362909&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSelect.cpp Sun Jun 9 09:22:01 2019
@@ -1883,22 +1883,34 @@ Instruction *InstCombiner::visitSelectIn
Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, X, FCI);
return replaceInstUsesWith(SI, Fabs);
}
- // With nsz:
- // (X < +/-0.0) ? -X : X --> fabs(X)
- // (X <= +/-0.0) ? -X : X --> fabs(X)
- // (X > +/-0.0) ? X : -X --> fabs(X)
- // (X >= +/-0.0) ? X : -X --> fabs(X)
- if (FCI->hasNoSignedZeros() &&
- ((X == FalseVal && match(TrueVal, m_FNeg(m_Specific(X))) &&
- (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE)) ||
- (X == TrueVal && match(FalseVal, m_FNeg(m_Specific(X))) &&
- (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE)))) {
- Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, X, FCI);
- return replaceInstUsesWith(SI, Fabs);
- }
}
}
+ // FIXME: These folds should test/propagate FMF from the select, not the fneg.
+ // With nnan and nsz:
+ // (X < +/-0.0) ? -X : X --> fabs(X)
+ // (X <= +/-0.0) ? -X : X --> fabs(X)
+ Instruction *FNeg;
+ if (match(CondVal, m_FCmp(Pred, m_Specific(FalseVal), m_AnyZeroFP())) &&
+ match(TrueVal, m_FNeg(m_Specific(FalseVal))) &&
+ match(TrueVal, m_Instruction(FNeg)) &&
+ FNeg->hasNoNaNs() && FNeg->hasNoSignedZeros() &&
+ (Pred == FCmpInst::FCMP_OLT || Pred == FCmpInst::FCMP_OLE)) {
+ Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, FalseVal, FNeg);
+ return replaceInstUsesWith(SI, Fabs);
+ }
+ // With nnan and nsz:
+ // (X > +/-0.0) ? X : -X --> fabs(X)
+ // (X >= +/-0.0) ? X : -X --> fabs(X)
+ if (match(CondVal, m_FCmp(Pred, m_Specific(TrueVal), m_AnyZeroFP())) &&
+ match(FalseVal, m_FNeg(m_Specific(TrueVal))) &&
+ match(FalseVal, m_Instruction(FNeg)) &&
+ FNeg->hasNoNaNs() && FNeg->hasNoSignedZeros() &&
+ (Pred == FCmpInst::FCMP_OGT || Pred == FCmpInst::FCMP_OGE)) {
+ Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs, TrueVal, FNeg);
+ return replaceInstUsesWith(SI, Fabs);
+ }
+
// See if we are selecting two values based on a comparison of the two values.
if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
Modified: llvm/trunk/test/Transforms/InstCombine/fabs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fabs.ll?rev=362909&r1=362908&r2=362909&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fabs.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fabs.ll Sun Jun 9 09:22:01 2019
@@ -321,8 +321,8 @@ define double @select_fcmp_nnan_nsz_olt_
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: ret double [[TMP1]]
;
- %ltzero = fcmp nnan nsz olt double %x, 0.0
- %negx = fsub double -0.0, %x
+ %ltzero = fcmp olt double %x, 0.0
+ %negx = fsub nnan nsz double -0.0, %x
%fabs = select i1 %ltzero, double %negx, double %x
ret double %fabs
}
@@ -332,8 +332,8 @@ define double @select_fcmp_nnan_nsz_olt_
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: ret double [[TMP1]]
;
- %ltzero = fcmp nnan nsz olt double %x, 0.0
- %negx = fneg double %x
+ %ltzero = fcmp olt double %x, 0.0
+ %negx = fneg nnan nsz double %x
%fabs = select i1 %ltzero, double %negx, double %x
ret double %fabs
}
@@ -345,8 +345,8 @@ define float @select_fcmp_nnan_nsz_olt_n
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf nsz float @llvm.fabs.f32(float [[X:%.*]])
; CHECK-NEXT: ret float [[TMP1]]
;
- %ltzero = fcmp nnan nsz ninf olt float %x, -0.0
- %negx = fsub float -0.0, %x
+ %ltzero = fcmp olt float %x, -0.0
+ %negx = fsub nnan ninf nsz float -0.0, %x
%fabs = select i1 %ltzero, float %negx, float %x
ret float %fabs
}
@@ -356,8 +356,8 @@ define float @select_fcmp_nnan_nsz_olt_n
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf nsz float @llvm.fabs.f32(float [[X:%.*]])
; CHECK-NEXT: ret float [[TMP1]]
;
- %ltzero = fcmp nnan nsz ninf olt float %x, -0.0
- %negx = fneg float %x
+ %ltzero = fcmp olt float %x, -0.0
+ %negx = fneg nnan ninf nsz float %x
%fabs = select i1 %ltzero, float %negx, float %x
ret float %fabs
}
@@ -369,8 +369,8 @@ define double @select_fcmp_nnan_nsz_ole_
; CHECK-NEXT: [[TMP1:%.*]] = call fast double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: ret double [[TMP1]]
;
- %lezero = fcmp fast ole double %x, 0.0
- %negx = fsub double -0.0, %x
+ %lezero = fcmp ole double %x, 0.0
+ %negx = fsub fast double -0.0, %x
%fabs = select i1 %lezero, double %negx, double %x
ret double %fabs
}
@@ -380,8 +380,8 @@ define double @select_fcmp_nnan_nsz_ole_
; CHECK-NEXT: [[TMP1:%.*]] = call fast double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: ret double [[TMP1]]
;
- %lezero = fcmp fast ole double %x, 0.0
- %negx = fneg double %x
+ %lezero = fcmp ole double %x, 0.0
+ %negx = fneg fast double %x
%fabs = select i1 %lezero, double %negx, double %x
ret double %fabs
}
@@ -393,8 +393,8 @@ define float @select_fcmp_nnan_nsz_ole_n
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz float @llvm.fabs.f32(float [[X:%.*]])
; CHECK-NEXT: ret float [[TMP1]]
;
- %lezero = fcmp nnan nsz ole float %x, -0.0
- %negx = fsub float -0.0, %x
+ %lezero = fcmp ole float %x, -0.0
+ %negx = fsub nnan nsz float -0.0, %x
%fabs = select i1 %lezero, float %negx, float %x
ret float %fabs
}
@@ -404,8 +404,8 @@ define float @select_fcmp_nnan_nsz_ole_n
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz float @llvm.fabs.f32(float [[X:%.*]])
; CHECK-NEXT: ret float [[TMP1]]
;
- %lezero = fcmp nnan nsz ole float %x, -0.0
- %negx = fneg float %x
+ %lezero = fcmp ole float %x, -0.0
+ %negx = fneg nnan nsz float %x
%fabs = select i1 %lezero, float %negx, float %x
ret float %fabs
}
@@ -417,8 +417,8 @@ define <2 x float> @select_fcmp_nnan_nsz
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz arcp <2 x float> @llvm.fabs.v2f32(<2 x float> [[X:%.*]])
; CHECK-NEXT: ret <2 x float> [[TMP1]]
;
- %gtzero = fcmp nnan nsz arcp ogt <2 x float> %x, zeroinitializer
- %negx = fsub <2 x float> <float -0.0, float -0.0>, %x
+ %gtzero = fcmp ogt <2 x float> %x, zeroinitializer
+ %negx = fsub nnan nsz arcp <2 x float> <float -0.0, float -0.0>, %x
%fabs = select <2 x i1> %gtzero, <2 x float> %x, <2 x float> %negx
ret <2 x float> %fabs
}
@@ -428,8 +428,8 @@ define <2 x float> @select_fcmp_nnan_nsz
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz arcp <2 x float> @llvm.fabs.v2f32(<2 x float> [[X:%.*]])
; CHECK-NEXT: ret <2 x float> [[TMP1]]
;
- %gtzero = fcmp nnan nsz arcp ogt <2 x float> %x, zeroinitializer
- %negx = fneg <2 x float> %x
+ %gtzero = fcmp ogt <2 x float> %x, zeroinitializer
+ %negx = fneg nnan nsz arcp <2 x float> %x
%fabs = select <2 x i1> %gtzero, <2 x float> %x, <2 x float> %negx
ret <2 x float> %fabs
}
@@ -441,8 +441,8 @@ define half @select_fcmp_nnan_nsz_ogt_ne
; CHECK-NEXT: [[TMP1:%.*]] = call fast half @llvm.fabs.f16(half [[X:%.*]])
; CHECK-NEXT: ret half [[TMP1]]
;
- %gtzero = fcmp fast ogt half %x, -0.0
- %negx = fsub half 0.0, %x
+ %gtzero = fcmp ogt half %x, -0.0
+ %negx = fsub fast half 0.0, %x
%fabs = select i1 %gtzero, half %x, half %negx
ret half %fabs
}
@@ -454,8 +454,8 @@ define <2 x double> @select_fcmp_nnan_ns
; CHECK-NEXT: [[TMP1:%.*]] = call reassoc nnan nsz <2 x double> @llvm.fabs.v2f64(<2 x double> [[X:%.*]])
; CHECK-NEXT: ret <2 x double> [[TMP1]]
;
- %gezero = fcmp nnan nsz reassoc oge <2 x double> %x, zeroinitializer
- %negx = fsub <2 x double> <double -0.0, double -0.0>, %x
+ %gezero = fcmp oge <2 x double> %x, zeroinitializer
+ %negx = fsub nnan nsz reassoc <2 x double> <double -0.0, double -0.0>, %x
%fabs = select <2 x i1> %gezero, <2 x double> %x, <2 x double> %negx
ret <2 x double> %fabs
}
@@ -465,8 +465,8 @@ define <2 x double> @select_fcmp_nnan_ns
; CHECK-NEXT: [[TMP1:%.*]] = call reassoc nnan nsz <2 x double> @llvm.fabs.v2f64(<2 x double> [[X:%.*]])
; CHECK-NEXT: ret <2 x double> [[TMP1]]
;
- %gezero = fcmp nnan nsz reassoc oge <2 x double> %x, zeroinitializer
- %negx = fneg <2 x double> %x
+ %gezero = fcmp oge <2 x double> %x, zeroinitializer
+ %negx = fneg nnan nsz reassoc <2 x double> %x
%fabs = select <2 x i1> %gezero, <2 x double> %x, <2 x double> %negx
ret <2 x double> %fabs
}
@@ -478,8 +478,8 @@ define half @select_fcmp_nnan_nsz_oge_ne
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz half @llvm.fabs.f16(half [[X:%.*]])
; CHECK-NEXT: ret half [[TMP1]]
;
- %gezero = fcmp nnan nsz oge half %x, -0.0
- %negx = fsub half -0.0, %x
+ %gezero = fcmp oge half %x, -0.0
+ %negx = fsub nnan nsz half -0.0, %x
%fabs = select i1 %gezero, half %x, half %negx
ret half %fabs
}
@@ -489,8 +489,8 @@ define half @select_fcmp_nnan_nsz_oge_ne
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz half @llvm.fabs.f16(half [[X:%.*]])
; CHECK-NEXT: ret half [[TMP1]]
;
- %gezero = fcmp nnan nsz oge half %x, -0.0
- %negx = fneg half %x
+ %gezero = fcmp oge half %x, -0.0
+ %negx = fneg nnan nsz half %x
%fabs = select i1 %gezero, half %x, half %negx
ret half %fabs
}
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