[llvm] r345725 - [InstSimplify] fold 'fcmp nnan oge X, 0.0' when X is not negative
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 31 07:57:23 PDT 2018
Author: spatel
Date: Wed Oct 31 07:57:23 2018
New Revision: 345725
URL: http://llvm.org/viewvc/llvm-project?rev=345725&view=rev
Log:
[InstSimplify] fold 'fcmp nnan oge X, 0.0' when X is not negative
This re-raises some of the open questions about how to apply and use fast-math-flags in IR from PR38086:
https://bugs.llvm.org/show_bug.cgi?id=38086
...but given the current implementation (no FMF on casts), this is likely the only way to predicate the
transform.
This is part of solving PR39475:
https://bugs.llvm.org/show_bug.cgi?id=39475
Differential Revision: https://reviews.llvm.org/D53874
Modified:
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.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=345725&r1=345724&r2=345725&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Wed Oct 31 07:57:23 2018
@@ -3612,6 +3612,10 @@ 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);
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=345725&r1=345724&r2=345725&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Wed Oct 31 07:57:23 2018
@@ -5433,8 +5433,8 @@ Instruction *InstCombiner::visitFCmpInst
break;
// fabs(x) < 0 --> false
case FCmpInst::FCMP_OLT:
- llvm_unreachable("handled by SimplifyFCmpInst");
- // fabs(x) > 0 --> x != 0
+ llvm_unreachable("fcmp should have simplified");
+ // fabs(x) > 0 --> x != 0
case FCmpInst::FCMP_OGT:
return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), RHSC);
// fabs(x) <= 0 --> x == 0
@@ -5442,6 +5442,7 @@ Instruction *InstCombiner::visitFCmpInst
return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), RHSC);
// fabs(x) >= 0 --> !isnan(x)
case FCmpInst::FCMP_OGE:
+ assert(!I.hasNoNaNs() && "fcmp should have simplified");
return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), RHSC);
// fabs(x) == 0 --> x == 0
// fabs(x) != 0 --> x != 0
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=345725&r1=345724&r2=345725&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/floating-point-compare.ll Wed Oct 31 07:57:23 2018
@@ -254,9 +254,7 @@ define <2 x i1> @UIToFP_is_nan_or_positi
define i1 @UIToFP_nnan_is_positive_or_zero(i32 %x) {
; CHECK-LABEL: @UIToFP_nnan_is_positive_or_zero(
-; CHECK-NEXT: [[A:%.*]] = uitofp i32 [[X:%.*]] to float
-; CHECK-NEXT: [[R:%.*]] = fcmp nnan oge float [[A]], 0.000000e+00
-; CHECK-NEXT: ret i1 [[R]]
+; CHECK-NEXT: ret i1 true
;
%a = uitofp i32 %x to float
%r = fcmp nnan oge float %a, 0.000000e+00
@@ -265,9 +263,7 @@ define i1 @UIToFP_nnan_is_positive_or_ze
define <2 x i1> @UIToFP_nnan_is_positive_or_zero_vec(<2 x i32> %x) {
; CHECK-LABEL: @UIToFP_nnan_is_positive_or_zero_vec(
-; CHECK-NEXT: [[A:%.*]] = uitofp <2 x i32> [[X:%.*]] to <2 x float>
-; CHECK-NEXT: [[R:%.*]] = fcmp nnan oge <2 x float> [[A]], zeroinitializer
-; CHECK-NEXT: ret <2 x i1> [[R]]
+; CHECK-NEXT: ret <2 x i1> <i1 true, i1 true>
;
%a = uitofp <2 x i32> %x to <2 x float>
%r = fcmp nnan oge <2 x float> %a, zeroinitializer
@@ -334,9 +330,7 @@ define <2 x i1> @fabs_is_nan_or_positive
define i1 @fabs_nnan_is_positive_or_zero(double %x) {
; CHECK-LABEL: @fabs_nnan_is_positive_or_zero(
-; CHECK-NEXT: [[FABS:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = fcmp nnan oge double [[FABS]], 0.000000e+00
-; CHECK-NEXT: ret i1 [[CMP]]
+; CHECK-NEXT: ret i1 true
;
%fabs = tail call double @llvm.fabs.f64(double %x)
%cmp = fcmp nnan oge double %fabs, 0.0
@@ -345,9 +339,7 @@ define i1 @fabs_nnan_is_positive_or_zero
define <2 x i1> @fabs_nnan_is_positive_or_zero_vec(<2 x double> %x) {
; CHECK-LABEL: @fabs_nnan_is_positive_or_zero_vec(
-; CHECK-NEXT: [[FABS:%.*]] = tail call <2 x double> @llvm.fabs.v2f64(<2 x double> [[X:%.*]])
-; CHECK-NEXT: [[CMP:%.*]] = fcmp nnan oge <2 x double> [[FABS]], zeroinitializer
-; CHECK-NEXT: ret <2 x i1> [[CMP]]
+; CHECK-NEXT: ret <2 x i1> <i1 true, i1 true>
;
%fabs = tail call <2 x double> @llvm.fabs.v2f64(<2 x double> %x)
%cmp = fcmp nnan oge <2 x double> %fabs, zeroinitializer
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