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[ValueTracking] add logic for known-never-nan with minnum/maxnum 

From the LangRef: "Returns NaN only if both operands are NaN."

llvm-svn: 360206
This commit is contained in:
Sanjay Patel 2019-05-07 22:58:31 +00:00
parent 0d8ae1e343
commit e088d03b9c
2 changed files with 7 additions and 6 deletions
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5
llvm/lib/Analysis/ValueTracking.cpp
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@ -3136,6 +3136,11 @@ bool llvm::isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
case Intrinsic::sqrt:
return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) &&
CannotBeOrderedLessThanZero(II->getArgOperand(0), TLI);
case Intrinsic::minnum:
case Intrinsic::maxnum:
// If either operand is not NaN, the result is not NaN.
return isKnownNeverNaN(II->getArgOperand(0), TLI, Depth + 1) ||
isKnownNeverNaN(II->getArgOperand(1), TLI, Depth + 1);
default:
return false;
}

8
llvm/test/Transforms/InstSimplify/floating-point-compare.ll
View File

@ -487,9 +487,7 @@ define i1 @orderedLessZeroMaximum(float, float) {
define i1 @minnum_non_nan(float %x) {
; CHECK-LABEL: @minnum_non_nan(
; CHECK-NEXT: [[MIN:%.*]] = call float @llvm.minnum.f32(float 5.000000e-01, float [[X:%.*]])
; CHECK-NEXT: [[CMP:%.*]] = fcmp ord float [[MIN]], 1.000000e+00
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 true
;
%min = call float @llvm.minnum.f32(float 0.5, float %x)
%cmp = fcmp ord float %min, 1.0
@ -498,9 +496,7 @@ define i1 @minnum_non_nan(float %x) {
define i1 @maxnum_non_nan(float %x) {
; CHECK-LABEL: @maxnum_non_nan(
; CHECK-NEXT: [[MIN:%.*]] = call float @llvm.maxnum.f32(float [[X:%.*]], float 4.200000e+01)
; CHECK-NEXT: [[CMP:%.*]] = fcmp uno float [[MIN]], 1.200000e+01
; CHECK-NEXT: ret i1 [[CMP]]
; CHECK-NEXT: ret i1 false
;
%min = call float @llvm.maxnum.f32(float %x, float 42.0)
%cmp = fcmp uno float %min, 12.0