ValueTracking: Implement computeKnownFPClass for fma/fmuladd

[arsenm]

Summary

Copy handling from CannotBeOrderedLessThanZero

[foad]

llvm/lib/Analysis/ValueTracking.cpp

4255

Could immediately do Known.knownNot(fcNegZero) here, since the x * x part can't be -0.

[arsenm]

Never -0

[arsenm]

a070dbfd14d6154b4d3f1bbd55d901429ad8ac79

llvm/lib/Analysis/ValueTracking.cpp

if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op)) {
         if (KnownSrc.isKnownNeverLogicalNegZero(*II->getFunction(),
                                                 II->getType())) {
           Known.knownNot(fcNegZero);
           Known.SignBit = false;
         }
 
         break;
       }
+      case Intrinsic::fma:
+      case Intrinsic::fmuladd: {
+        if ((InterestedClasses & fcNegative) == fcNone)
+          break;
+
+        if (II->getArgOperand(0) != II->getArgOperand(1))
+          break;
+
+        // The multiply cannot be -0 and therefore the add can't be -0
+        Known.knownNot(fcNegZero);
+
+        // x * x + y is non-negative if y is non-negative.
+        KnownFPClass KnownAddend;
+        computeKnownFPClass(II->getArgOperand(2), DemandedElts,
+                            InterestedClasses, KnownAddend, Depth + 1, Q, TLI);
+
+        // TODO: Known sign bit with no nans
+        if (KnownAddend.cannotBeOrderedLessThanZero())
+          Known.knownNot(fcNegative);
+        break;
+      }
       case Intrinsic::sin:
       case Intrinsic::cos: {
         // Return NaN on infinite inputs.
         KnownFPClass KnownSrc;
         computeKnownFPClass(II->getArgOperand(0), DemandedElts,
                             InterestedClasses, KnownSrc, Depth + 1, Q, TLI);
         Known.knownNot(fcInf);
         if (KnownSrc.isKnownNeverNaN() && KnownSrc.isKnownNeverInfinity())

llvm/test/Transforms/Attributor/nofpclass-fma.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
 ; RUN: opt -aa-pipeline=basic-aa -passes=attributor -attributor-manifest-internal -S < %s | FileCheck %s --check-prefixes=CHECK,TUNIT
 
 declare float @llvm.fma.f32(float, float, float)
 declare float @llvm.fmuladd.f32(float, float, float)
 
 define float @ret_fma_same_mul_arg(float %arg0, float %arg1) {
-; CHECK-LABEL: define float @ret_fma_same_mul_arg
+; CHECK-LABEL: define nofpclass(nzero) float @ret_fma_same_mul_arg
 ; CHECK-SAME: (float [[ARG0:%.*]], float [[ARG1:%.*]]) #[[ATTR1:[0-9]+]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.fma.f32(float [[ARG0]], float [[ARG0]], float [[ARG1]]) #[[ATTR2:[0-9]+]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(nzero) float @llvm.fma.f32(float [[ARG0]], float [[ARG0]], float [[ARG1]]) #[[ATTR2:[0-9]+]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.fma.f32(float %arg0, float %arg0, float %arg1)
   ret float %call
 }
 
 define float @ret_fma_same_mul_arg_positive_addend(float %arg0, float nofpclass(ninf nsub nnorm) %arg1) {
-; CHECK-LABEL: define float @ret_fma_same_mul_arg_positive_addend
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_fma_same_mul_arg_positive_addend
 ; CHECK-SAME: (float [[ARG0:%.*]], float nofpclass(ninf nsub nnorm) [[ARG1:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.fma.f32(float [[ARG0]], float [[ARG0]], float [[ARG1]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(ninf nzero nsub nnorm) float @llvm.fma.f32(float [[ARG0]], float [[ARG0]], float [[ARG1]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.fma.f32(float %arg0, float %arg0, float %arg1)
   ret float %call
 }
 
 define float @ret_fma_different_mul_arg_positive_addend(float %arg0, float %arg1, float nofpclass(ninf nsub nnorm) %arg2) {
 ; CHECK-LABEL: define float @ret_fma_different_mul_arg_positive_addend
 ; CHECK-SAME: (float [[ARG0:%.*]], float [[ARG1:%.*]], float nofpclass(ninf nsub nnorm) [[ARG2:%.*]]) #[[ATTR1]] {
 ; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.fma.f32(float [[ARG0]], float [[ARG1]], float [[ARG2]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.fma.f32(float %arg0, float %arg1, float %arg2)
   ret float %call
 }
 
 define float @ret_fmuladd_different_same_arg_positive_addend(float %arg0, float nofpclass(ninf nsub nnorm) %arg1) {
-; CHECK-LABEL: define float @ret_fmuladd_different_same_arg_positive_addend
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_fmuladd_different_same_arg_positive_addend
 ; CHECK-SAME: (float [[ARG0:%.*]], float nofpclass(ninf nsub nnorm) [[ARG1:%.*]]) #[[ATTR1]] {
-; CHECK-NEXT:    [[CALL:%.*]] = call float @llvm.fmuladd.f32(float [[ARG0]], float [[ARG0]], float [[ARG1]]) #[[ATTR2]]
+; CHECK-NEXT:    [[CALL:%.*]] = call nofpclass(ninf nzero nsub nnorm) float @llvm.fmuladd.f32(float [[ARG0]], float [[ARG0]], float [[ARG1]]) #[[ATTR2]]
 ; CHECK-NEXT:    ret float [[CALL]]
 ;
   %call = call float @llvm.fmuladd.f32(float %arg0, float %arg0, float %arg1)
   ret float %call
 }
 
 ;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
 ; TUNIT: {{.*}}