[PATCH] D147856: ValueTracking: Handle no-nan check for computeKnownFPClass for fmul
Matt Arsenault via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sat Apr 8 12:27:21 PDT 2023
arsenm created this revision.
arsenm added reviewers: jcranmer-intel, kpn, cameron.mcinally, sepavloff, nikic, andrew.w.kaylor, scanon.
Herald added subscribers: StephenFan, hiraditya.
Herald added a project: All.
arsenm requested review of this revision.
Herald added a subscriber: wdng.
Herald added a project: LLVM.
Copy the logic from isKnownNeverNaN for fadd/fsub. Leave the
extension to handle the zero case for a future change (which also doesn't sound right to me)
https://reviews.llvm.org/D147856
Files:
llvm/lib/Analysis/ValueTracking.cpp
llvm/unittests/Analysis/ValueTrackingTest.cpp
Index: llvm/unittests/Analysis/ValueTrackingTest.cpp
===================================================================
--- llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1575,6 +1575,23 @@
expectKnownFPClass(fcAllFlags, std::nullopt, A5);
}
+TEST_F(ComputeKnownFPClassTest, FMul) {
+ parseAssembly(
+ "define float @test(float nofpclass(nan inf) %nnan.ninf, float nofpclass(nan) %nnan, float nofpclass(qnan) %no.qnan, float %unknown) {\n"
+ " %A = fmul float %nnan.ninf, %nnan.ninf"
+ " %A2 = fmul float %nnan.ninf, %nnan"
+ " %A3 = fmul float %nnan, %nnan.ninf"
+ " %A4 = fmul float %nnan.ninf, %no.qnan"
+ " %A5 = fmul float %nnan, %nnan"
+ " ret float %A\n"
+ "}\n");
+ expectKnownFPClass(fcFinite | fcInf, std::nullopt, A);
+ expectKnownFPClass(fcAllFlags, std::nullopt, A2);
+ expectKnownFPClass(fcAllFlags, std::nullopt, A3);
+ expectKnownFPClass(fcAllFlags, std::nullopt, A4);
+ expectKnownFPClass(fcAllFlags, std::nullopt, A5);
+}
+
TEST_F(ValueTrackingTest, isNonZeroRecurrence) {
parseAssembly(R"(
define i1 @test(i8 %n, i8 %r) {
Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -4457,6 +4457,22 @@
break;
}
+ case Instruction::FMul: {
+ KnownFPClass KnownLHS, KnownRHS;
+ computeKnownFPClass(Op->getOperand(1), DemandedElts, fcNan | fcInf,
+ KnownRHS, Depth + 1, Q, TLI);
+ if (KnownRHS.isKnownNeverNaN() && KnownRHS.isKnownNeverInfinity()) {
+ computeKnownFPClass(Op->getOperand(0), DemandedElts, fcNan | fcInf,
+ KnownLHS, Depth + 1, Q, TLI);
+
+ // Zero multiplied with infinity produces NaN.
+ // FIXME: If neither side can be zero fmul never produces NaN.
+ if (KnownLHS.isKnownNeverNaN() && KnownLHS.isKnownNeverInfinity())
+ Known.knownNot(fcNan);
+ }
+
+ break;
+ }
case Instruction::SIToFP:
case Instruction::UIToFP: {
// Cannot produce nan
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