[llvm] APFloat: Add helpers to query NaN/inf semantics (#116315)

`APFloat` changes extracted from #116176 as per reviewer comments.

Author: matthias-springer

llvm/include/llvm/ADT/APFloat.h

@@ -311,7 +311,8 @@ struct APFloatBase {
   static unsigned int semanticsIntSizeInBits(const fltSemantics&, bool);
   static bool semanticsHasZero(const fltSemantics &);
   static bool semanticsHasSignedRepr(const fltSemantics &);
-  static bool semanticsHasNanOrInf(const fltSemantics &);
+  static bool semanticsHasInf(const fltSemantics &);
+  static bool semanticsHasNaN(const fltSemantics &);
 
   // Returns true if any number described by \p Src can be precisely represented
   // by a normal (not subnormal) value in \p Dst.

llvm/lib/Support/APFloat.cpp

@@ -375,7 +375,11 @@ bool APFloatBase::semanticsHasSignedRepr(const fltSemantics &semantics) {
   return semantics.hasSignedRepr;
 }
 
-bool APFloatBase::semanticsHasNanOrInf(const fltSemantics &semantics) {
+bool APFloatBase::semanticsHasInf(const fltSemantics &semantics) {
+  return semantics.nonFiniteBehavior == fltNonfiniteBehavior::IEEE754;
+}
+
+bool APFloatBase::semanticsHasNaN(const fltSemantics &semantics) {
   return semantics.nonFiniteBehavior != fltNonfiniteBehavior::FiniteOnly;
 }
 

llvm/unittests/ADT/APFloatTest.cpp

@@ -832,8 +832,9 @@ TEST(APFloatTest, IsSmallestNormalized) {
     EXPECT_FALSE(APFloat::getZero(Semantics, false).isSmallestNormalized());
     EXPECT_FALSE(APFloat::getZero(Semantics, true).isSmallestNormalized());
 
-    if (APFloat::semanticsHasNanOrInf(Semantics)) {
+    if (APFloat::semanticsHasNaN(Semantics)) {
       // Types that do not support Inf will return NaN when asked for Inf.
+      // (But only if they support NaN.)
       EXPECT_FALSE(APFloat::getInf(Semantics, false).isSmallestNormalized());
       EXPECT_FALSE(APFloat::getInf(Semantics, true).isSmallestNormalized());
 
@@ -2557,6 +2558,14 @@ TEST(APFloatTest, isInfinity) {
   EXPECT_FALSE(APFloat::getNaN(APFloat::IEEEsingle(), false).isInfinity());
   EXPECT_FALSE(APFloat::getSNaN(APFloat::IEEEsingle(), false).isInfinity());
   EXPECT_FALSE(APFloat(APFloat::IEEEsingle(), "0x1p-149").isInfinity());
+
+  for (unsigned I = 0; I != APFloat::S_MaxSemantics + 1; ++I) {
+    const fltSemantics &Semantics =
+        APFloat::EnumToSemantics(static_cast<APFloat::Semantics>(I));
+    if (APFloat::semanticsHasInf(Semantics)) {
+      EXPECT_TRUE(APFloat::getInf(Semantics).isInfinity());
+    }
+  }
 }
 
 TEST(APFloatTest, isNaN) {
@@ -2567,6 +2576,14 @@ TEST(APFloatTest, isNaN) {
   EXPECT_TRUE(APFloat::getNaN(APFloat::IEEEsingle(), false).isNaN());
   EXPECT_TRUE(APFloat::getSNaN(APFloat::IEEEsingle(), false).isNaN());
   EXPECT_FALSE(APFloat(APFloat::IEEEsingle(), "0x1p-149").isNaN());
+
+  for (unsigned I = 0; I != APFloat::S_MaxSemantics + 1; ++I) {
+    const fltSemantics &Semantics =
+        APFloat::EnumToSemantics(static_cast<APFloat::Semantics>(I));
+    if (APFloat::semanticsHasNaN(Semantics)) {
+      EXPECT_TRUE(APFloat::getNaN(Semantics).isNaN());
+    }
+  }
 }
 
 TEST(APFloatTest, isFiniteNonZero) {
@@ -7345,8 +7362,9 @@ TEST(APFloatTest, getExactLog2) {
     EXPECT_EQ(INT_MIN, APFloat::getZero(Semantics, false).getExactLog2Abs());
     EXPECT_EQ(INT_MIN, APFloat::getZero(Semantics, true).getExactLog2Abs());
 
-    if (APFloat::semanticsHasNanOrInf(Semantics)) {
+    if (APFloat::semanticsHasNaN(Semantics)) {
       // Types that do not support Inf will return NaN when asked for Inf.
+      // (But only if they support NaN.)
       EXPECT_EQ(INT_MIN, APFloat::getInf(Semantics).getExactLog2());
       EXPECT_EQ(INT_MIN, APFloat::getInf(Semantics, true).getExactLog2());
       EXPECT_EQ(INT_MIN, APFloat::getNaN(Semantics, false).getExactLog2());