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[InstSimplify] Allow folding of fdiv X, X with just NaNs ignored

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Any combination of +-inf/+-inf is NaN so it's already ignored with
nnan and we can skip checking for ninf. Also rephrase logic in comments
a bit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239821 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2015-06-16 14:57:29 +00:00
parent cc73f10648
commit 8a8bb45a76
2 changed files with 32 additions and 52 deletions
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6
lib/Analysis/InstructionSimplify.cpp
View File

@ -1126,13 +1126,13 @@ static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
return Op0;
if (FMF.noNaNs() && FMF.noInfs()) {
// X / X -> 1.0 iff NaNs and infinities are ignored.
if (FMF.noNaNs()) {
// X / X -> 1.0 is legal when NaNs are ignored.
if (Op0 == Op1)
return ConstantFP::get(Op0->getType(), 1.0);
// -X / X -> -1.0 and
// X / -X -> -1.0 iff NaNs and infinities are ignored.
// X / -X -> -1.0 are legal when NaNs are ignored.
// We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
if ((BinaryOperator::isFNeg(Op0, /*IgnoreZeroSign=*/true) &&
BinaryOperator::getFNegArgument(Op0) == Op1) ||

78
test/Transforms/InstSimplify/fast-math.ll
View File

@ -115,79 +115,59 @@ define double @fdiv_zero_by_x(double %X) {
; CHECK: ret double 0
}
define float @fdiv_self(float %f) {
%div = fdiv nnan ninf float %f, %f
define float @fdiv_self(float %f) {
%div = fdiv nnan float %f, %f
ret float %div
; CHECK-LABEL: fdiv_self
; CHECK: ret float 1.000000e+00
}
define float @fdiv_self_invalid1(float %f) {
%div = fdiv ninf float %f, %f
ret float %div
; CHECK-LABEL: fdiv_self_invalid1
; CHECK: %div = fdiv ninf float %f, %f
; CHECK-NEXT: ret float %div
}
define float @fdiv_self_invalid2(float %f) {
%div = fdiv nnan float %f, %f
ret float %div
; CHECK-LABEL: fdiv_self_invalid2
; CHECK: %div = fdiv nnan float %f, %f
; CHECK-NEXT: ret float %div
}
define float @fdiv_self_invalid3(float %f) {
define float @fdiv_self_invalid(float %f) {
%div = fdiv float %f, %f
ret float %div
; CHECK-LABEL: fdiv_self_invalid3
; CHECK-LABEL: fdiv_self_invalid
; CHECK: %div = fdiv float %f, %f
; CHECK-NEXT: ret float %div
}
define float @fdiv_neg(float %f) {
%neg = fsub fast float -0.000000e+00, %f
%div = fdiv nnan ninf float %neg, %f
ret float %div
; CHECK-LABEL: fdiv_neg
; CHECK: ret float -1.000000e+00
}
define float @fdiv_neg_invalid1(float %f) {
%neg = fsub fast float -0.000000e+00, %f
%div = fdiv ninf float %neg, %f
ret float %div
; CHECK-LABEL: fdiv_neg_invalid1
; CHECK: %neg = fsub fast float -0.000000e+00, %f
; CHECK-NEXT: %div = fdiv ninf float %neg, %f
; CHECK-NEXT: ret float %div
}
define float @fdiv_neg_invalid2(float %f) {
define float @fdiv_neg1(float %f) {
%neg = fsub fast float -0.000000e+00, %f
%div = fdiv nnan float %neg, %f
ret float %div
; CHECK-LABEL: fdiv_neg_invalid2
; CHECK: %neg = fsub fast float -0.000000e+00, %f
; CHECK-NEXT: %div = fdiv nnan float %neg, %f
; CHECK-NEXT: ret float %div
; CHECK-LABEL: fdiv_neg1
; CHECK: ret float -1.000000e+00
}
define float @fdiv_neg_invalid3(float %f) {
define float @fdiv_neg2(float %f) {
%neg = fsub fast float 0.000000e+00, %f
%div = fdiv nnan float %neg, %f
ret float %div
; CHECK-LABEL: fdiv_neg2
; CHECK: ret float -1.000000e+00
}
define float @fdiv_neg_invalid(float %f) {
%neg = fsub fast float -0.000000e+00, %f
%div = fdiv float %neg, %f
ret float %div
; CHECK-LABEL: fdiv_neg_invalid3
; CHECK-LABEL: fdiv_neg_invalid
; CHECK: %neg = fsub fast float -0.000000e+00, %f
; CHECK-NEXT: %div = fdiv float %neg, %f
; CHECK-NEXT: ret float %div
}
define float @fdiv_neg_swapped(float %f) {
%neg = fsub float 0.000000e+00, %f
%div = fdiv nnan ninf float %f, %neg
define float @fdiv_neg_swapped1(float %f) {
%neg = fsub float -0.000000e+00, %f
%div = fdiv nnan float %f, %neg
ret float %div
; CHECK-LABEL: fdiv_neg_swapped
; CHECK-LABEL: fdiv_neg_swapped1
; CHECK: ret float -1.000000e+00
}
define float @fdiv_neg_swapped2(float %f) {
%neg = fsub float 0.000000e+00, %f
%div = fdiv nnan float %f, %neg
ret float %div
; CHECK-LABEL: fdiv_neg_swapped2
; CHECK: ret float -1.000000e+00
}