ValueTracking: Add ordered negative handling for fmul to computeKnownFPClass

[arsenm]

Summary

Port from the existing handling in cannotBeOrderedLessThanZero

[arsenm]

Test update

[arsenm]

f40d186d4a3a448bfb4233c52658a70e71ae04f1

llvm/lib/Analysis/ValueTracking.cpp

if (KnownRHS.isKnownNeverNaN()) {
       if (KnownLHS.isKnownNeverNaN() &&
           (KnownLHS.isKnownNeverInfinity() || KnownRHS.isKnownNeverInfinity()))
         Known.knownNot(fcNan);
     }
 
     break;
   }
   case Instruction::FMul: {
+    // X * X is always non-negative or a NaN.
+    if (Op->getOperand(0) == Op->getOperand(1))
+      Known.knownNot(fcNegative);
+
+    if ((InterestedClasses & fcNan) != fcNan)
+      break;
+
     KnownFPClass KnownLHS, KnownRHS;
     computeKnownFPClass(Op->getOperand(1), DemandedElts,
                         fcNan | fcInf | fcZero | fcSubnormal, KnownRHS,
                         Depth + 1, Q, TLI);
     if (KnownRHS.isKnownNeverNaN() &&
         (KnownRHS.isKnownNeverInfinity() || KnownRHS.isKnownNeverZero())) {
       computeKnownFPClass(Op->getOperand(0), DemandedElts,
                           fcNan | fcInf | fcZero, KnownLHS, Depth + 1, Q, TLI);

llvm/test/Transforms/Attributor/nofpclass-nan-fmul.ll

 ; CHECK-SAME: (float nofpclass(nan zero sub) [[ARG0:%.*]], float nofpclass(nan zero) [[ARG1:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[FMUL:%.*]] = fmul float [[ARG0]], [[ARG1]]
 ; CHECK-NEXT:    ret float [[FMUL]]
 ;
   %fmul = fmul float %arg0, %arg1
   ret float %fmul
 }
 
+define float @ret_fmul_square(float %arg) #0 {
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_fmul_square
+; CHECK-SAME: (float [[ARG:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT:    [[FMUL:%.*]] = fmul float [[ARG]], [[ARG]]
+; CHECK-NEXT:    ret float [[FMUL]]
+;
+  %fmul = fmul float %arg, %arg
+  ret float %fmul
+}
+
+define float @ret_fmul_square_nnan(float nofpclass(nan) %arg) #0 {
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_fmul_square_nnan
+; CHECK-SAME: (float nofpclass(nan) [[ARG:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT:    [[FMUL:%.*]] = fmul float [[ARG]], [[ARG]]
+; CHECK-NEXT:    ret float [[FMUL]]
+;
+  %fmul = fmul float %arg, %arg
+  ret float %fmul
+}
+
+define float @ret_fmul_square_nnan_nzero(float nofpclass(nan zero) %arg) #0 {
+; CHECK-LABEL: define nofpclass(nan ninf nzero nsub nnorm) float @ret_fmul_square_nnan_nzero
+; CHECK-SAME: (float nofpclass(nan zero) [[ARG:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT:    [[FMUL:%.*]] = fmul float [[ARG]], [[ARG]]
+; CHECK-NEXT:    ret float [[FMUL]]
+;
+  %fmul = fmul float %arg, %arg
+  ret float %fmul
+}
+
 attributes #0 = { "denormal-fp-math"="ieee,ieee" }
 attributes #1 = { "denormal-fp-math"="ieee,preserve-sign" }
 attributes #2 = { "denormal-fp-math"="ieee,positive-zero" }
 attributes #3 = { "denormal-fp-math"="ieee,dynamic" }
 ;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
 ; TUNIT: {{.*}}

llvm/unittests/Analysis/ValueTrackingTest.cpp

TEST_F(ComputeKnownFPClassTest, FSub) {
   expectKnownFPClass(fcFinite | fcInf, std::nullopt, A2);
   expectKnownFPClass(fcAllFlags, std::nullopt, A3);
   expectKnownFPClass(fcAllFlags, std::nullopt, A4);
   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"
+      "define float @test(float nofpclass(nan inf) %nnan.ninf0, float nofpclass(nan inf) %nnan.ninf1, float nofpclass(nan) %nnan, float nofpclass(qnan) %no.qnan, float %unknown) {\n"
+      "  %A = fmul float %nnan.ninf0, %nnan.ninf1"
+      "  %A2 = fmul float %nnan.ninf0, %nnan"
+      "  %A3 = fmul float %nnan, %nnan.ninf0"
+      "  %A4 = fmul float %nnan.ninf0, %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);
+  expectKnownFPClass(fcPositive | fcNan, std::nullopt, A5);
 }
 
 TEST_F(ComputeKnownFPClassTest, FMulNoZero) {
   parseAssembly(
-      "define float @test(float nofpclass(zero) %no.zero, float nofpclass(zero nan) %no.zero.nan, float nofpclass(nzero nan) %no.negzero.nan, float nofpclass(pzero nan) %no.poszero.nan, float nofpclass(inf nan) %no.inf.nan, float nofpclass(inf) %no.inf, float nofpclass(nan) %no.nan) {\n"
-      "  %A = fmul float %no.zero.nan, %no.zero.nan"
+      "define float @test(float nofpclass(zero) %no.zero, float nofpclass(zero nan) %no.zero.nan0, float nofpclass(zero nan) %no.zero.nan1, float nofpclass(nzero nan) %no.negzero.nan, float nofpclass(pzero nan) %no.poszero.nan, float nofpclass(inf nan) %no.inf.nan, float nofpclass(inf) %no.inf, float nofpclass(nan) %no.nan) {\n"
+      "  %A = fmul float %no.zero.nan0, %no.zero.nan1"
       "  %A2 = fmul float %no.zero, %no.zero"
-      "  %A3 = fmul float %no.poszero.nan, %no.zero.nan"
+      "  %A3 = fmul float %no.poszero.nan, %no.zero.nan0"
       "  %A4 = fmul float %no.nan, %no.zero"
       "  %A5 = fmul float %no.zero, %no.inf"
-      "  %A6 = fmul float %no.zero.nan, %no.nan"
-      "  %A7 = fmul float %no.nan, %no.zero.nan"
+      "  %A6 = fmul float %no.zero.nan0, %no.nan"
+      "  %A7 = fmul float %no.nan, %no.zero.nan0"
       "  ret float %A\n"
       "}\n");
   expectKnownFPClass(fcFinite | fcInf, std::nullopt, A);
-  expectKnownFPClass(fcAllFlags, std::nullopt, A2);
+  expectKnownFPClass(fcPositive | fcNan, std::nullopt, A2);
   expectKnownFPClass(fcAllFlags, std::nullopt, A3);
   expectKnownFPClass(fcAllFlags, std::nullopt, A4);
   expectKnownFPClass(fcAllFlags, std::nullopt, A5);
   expectKnownFPClass(fcAllFlags, std::nullopt, A6);
   expectKnownFPClass(fcAllFlags, std::nullopt, A7);
 }
 
 TEST_F(ComputeKnownFPClassTest, CannotBeOrderedLessThanZero) {