[llvm] fc7c706 - ValueTracking: Add cannotBeOrderedLessThanZero to KnownFPClass

[Matt Arsenault via llvm-commits]

Author: Matt Arsenault
Date: 2023-04-13T14:44:34-04:00
New Revision: fc7c706e3f93fa1f700a7ded2ae797aad32d892e

URL: https://github.com/llvm/llvm-project/commit/fc7c706e3f93fa1f700a7ded2ae797aad32d892e
DIFF: https://github.com/llvm/llvm-project/commit/fc7c706e3f93fa1f700a7ded2ae797aad32d892e.diff

LOG: ValueTracking: Add cannotBeOrderedLessThanZero to KnownFPClass

Eventually we should be able to replace the existing
CannotBeOrderedLessThanZero.

Added: 
    

Modified: 
    llvm/include/llvm/Analysis/ValueTracking.h
    llvm/unittests/Analysis/ValueTrackingTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index c3093d5209e6..85c6021eea24 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -265,6 +265,19 @@ struct KnownFPClass {
   /// floating-point mode for the function interprets denormals as zero.
   bool isKnownNeverLogicalZero(const Function &F, Type *Ty) const;
 
+  /// Return true if we can prove that the analyzed floating-point value is
+  /// either NaN or never less than -0.0.
+  ///
+  ///      NaN --> true
+  ///       +0 --> true
+  ///       -0 --> true
+  ///   x > +0 --> true
+  ///   x < -0 --> false
+  bool cannotBeOrderedLessThanZero() const {
+    const FPClassTest OrderedNegMask = fcNegSubnormal | fcNegNormal | fcNegInf;
+    return (KnownFPClasses & OrderedNegMask) == fcNone;
+  }
+
   KnownFPClass &operator|=(const KnownFPClass &RHS) {
     KnownFPClasses = KnownFPClasses | RHS.KnownFPClasses;
 

diff  --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp
index 211959f2895b..9327315304c8 100644
--- a/llvm/unittests/Analysis/ValueTrackingTest.cpp
+++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp
@@ -1616,6 +1616,59 @@ TEST_F(ComputeKnownFPClassTest, FMulNoZero) {
   expectKnownFPClass(fcAllFlags, std::nullopt, A7);
 }
 
+TEST_F(ComputeKnownFPClassTest, CannotBeOrderedLessThanZero) {
+  parseAssembly("define float @test(float %arg) {\n"
+                "  %A = fmul float %arg, %arg"
+                "  ret float %A\n"
+                "}\n");
+
+  Type *FPTy = Type::getDoubleTy(M->getContext());
+  const DataLayout &DL = M->getDataLayout();
+
+  EXPECT_TRUE(
+      computeKnownFPClass(ConstantFP::getZero(FPTy, /*Negative=*/false), DL)
+          .cannotBeOrderedLessThanZero());
+  EXPECT_TRUE(
+      computeKnownFPClass(ConstantFP::getZero(FPTy, /*Negative=*/true), DL)
+          .cannotBeOrderedLessThanZero());
+
+  EXPECT_TRUE(computeKnownFPClass(ConstantFP::getInfinity(FPTy, false), DL)
+                  .cannotBeOrderedLessThanZero());
+  EXPECT_FALSE(computeKnownFPClass(ConstantFP::getInfinity(FPTy, true), DL)
+                   .cannotBeOrderedLessThanZero());
+
+  EXPECT_TRUE(computeKnownFPClass(ConstantFP::get(FPTy, 1.0), DL)
+                  .cannotBeOrderedLessThanZero());
+  EXPECT_FALSE(computeKnownFPClass(ConstantFP::get(FPTy, -1.0), DL)
+                   .cannotBeOrderedLessThanZero());
+
+  EXPECT_TRUE(
+      computeKnownFPClass(
+          ConstantFP::get(FPTy, APFloat::getSmallest(FPTy->getFltSemantics(),
+                                                     /*Negative=*/false)),
+          DL)
+          .cannotBeOrderedLessThanZero());
+  EXPECT_FALSE(
+      computeKnownFPClass(
+          ConstantFP::get(FPTy, APFloat::getSmallest(FPTy->getFltSemantics(),
+                                                     /*Negative=*/true)),
+          DL)
+          .cannotBeOrderedLessThanZero());
+
+  EXPECT_TRUE(
+      computeKnownFPClass(ConstantFP::getQNaN(FPTy, /*Negative=*/false), DL)
+          .cannotBeOrderedLessThanZero());
+  EXPECT_TRUE(
+      computeKnownFPClass(ConstantFP::getQNaN(FPTy, /*Negative=*/true), DL)
+          .cannotBeOrderedLessThanZero());
+  EXPECT_TRUE(
+      computeKnownFPClass(ConstantFP::getSNaN(FPTy, /*Negative=*/false), DL)
+          .cannotBeOrderedLessThanZero());
+  EXPECT_TRUE(
+      computeKnownFPClass(ConstantFP::getSNaN(FPTy, /*Negative=*/true), DL)
+          .cannotBeOrderedLessThanZero());
+}
+
 TEST_F(ValueTrackingTest, isNonZeroRecurrence) {
   parseAssembly(R"(
     define i1 @test(i8 %n, i8 %r) {