[llvm] a070dbf - ValueTracking: Implement computeKnownFPClass for fma/fmuladd

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2023-04-24T14:29:35-04:00
New Revision: a070dbfd14d6154b4d3f1bbd55d901429ad8ac79

URL: https://github.com/llvm/llvm-project/commit/a070dbfd14d6154b4d3f1bbd55d901429ad8ac79
DIFF: https://github.com/llvm/llvm-project/commit/a070dbfd14d6154b4d3f1bbd55d901429ad8ac79.diff

LOG: ValueTracking: Implement computeKnownFPClass for fma/fmuladd

Copy handling from CannotBeOrderedLessThanZero

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/test/Transforms/Attributor/nofpclass-fma.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index b2d1406e98f3..6e7b807c1903 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4546,6 +4546,27 @@ void computeKnownFPClass(const Value *V, const APInt &DemandedElts,
         Known.copysign(KnownSign);
         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.

diff  --git a/llvm/test/Transforms/Attributor/nofpclass-fma.ll b/llvm/test/Transforms/Attributor/nofpclass-fma.ll
index 54cad8210911..07a01ae81f3b 100644
--- a/llvm/test/Transforms/Attributor/nofpclass-fma.ll
+++ b/llvm/test/Transforms/Attributor/nofpclass-fma.ll
@@ -5,9 +5,9 @@ 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)
@@ -15,9 +15,9 @@ define float @ret_fma_same_mul_arg(float %arg0, float %arg1) {
 }
 
 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)
@@ -35,9 +35,9 @@ define float @ret_fma_
diff erent_mul_arg_positive_addend(float %arg0, float %arg1
 }
 
 define float @ret_fmuladd_
diff erent_same_arg_positive_addend(float %arg0, float nofpclass(ninf nsub nnorm) %arg1) {
-; CHECK-LABEL: define float @ret_fmuladd_
diff erent_same_arg_positive_addend
+; CHECK-LABEL: define nofpclass(ninf nzero nsub nnorm) float @ret_fmuladd_
diff erent_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)