Support constant folding of more common built-ins

src/common/mathutil.h

@@ -622,6 +622,24 @@ inline void unpackHalf2x16(uint32_t u, float *f1, float *f2)
     *f2 = float16ToFloat32(mostSignificantBits);
 }
 
+// Returns whether the argument is Not a Number.
+// IEEE 754 single precision NaN representation: Exponent(8 bits) - 255, Mantissa(23 bits) - non-zero.
+inline bool isNaN(float f)
+{
+    // Exponent mask: ((1u << 8) - 1u) << 23 = 0x7f800000u
+    // Mantissa mask: ((1u << 23) - 1u) = 0x7fffffu
+    return ((bitCast<uint32_t>(f) & 0x7f800000u) == 0x7f800000u) && (bitCast<uint32_t>(f) & 0x7fffffu);
+}
+
+// Returns whether the argument is infinity.
+// IEEE 754 single precision infinity representation: Exponent(8 bits) - 255, Mantissa(23 bits) - zero.
+inline bool isInf(float f)
+{
+    // Exponent mask: ((1u << 8) - 1u) << 23 = 0x7f800000u
+    // Mantissa mask: ((1u << 23) - 1u) = 0x7fffffu
+    return ((bitCast<uint32_t>(f) & 0x7f800000u) == 0x7f800000u) && !(bitCast<uint32_t>(f) & 0x7fffffu);
+}
+
 }
 
 namespace rx

src/common/mathutil_unittest.cpp

@@ -142,5 +142,31 @@ TEST(MathUtilTest, packAndUnpackHalf2x16)
     }
 }
 
+// Test the correctness of gl::isNaN function.
+TEST(MathUtilTest, isNaN)
+{
+    EXPECT_TRUE(isNaN(bitCast<float>(0xffu << 23 | 1u)));
+    EXPECT_TRUE(isNaN(bitCast<float>(1u << 31 | 0xffu << 23 | 1u)));
+    EXPECT_TRUE(isNaN(bitCast<float>(1u << 31 | 0xffu << 23 | 0x400000u)));
+    EXPECT_TRUE(isNaN(bitCast<float>(1u << 31 | 0xffu << 23 | 0x7fffffu)));
+    EXPECT_FALSE(isNaN(0.0f));
+    EXPECT_FALSE(isNaN(bitCast<float>(1u << 31 | 0xffu << 23)));
+    EXPECT_FALSE(isNaN(bitCast<float>(0xffu << 23)));
+}
+
+// Test the correctness of gl::isInf function.
+TEST(MathUtilTest, isInf)
+{
+    EXPECT_TRUE(isInf(bitCast<float>(0xffu << 23)));
+    EXPECT_TRUE(isInf(bitCast<float>(1u << 31 | 0xffu << 23)));
+    EXPECT_FALSE(isInf(0.0f));
+    EXPECT_FALSE(isInf(bitCast<float>(0xffu << 23 | 1u)));
+    EXPECT_FALSE(isInf(bitCast<float>(1u << 31 | 0xffu << 23 | 1u)));
+    EXPECT_FALSE(isInf(bitCast<float>(1u << 31 | 0xffu << 23 | 0x400000u)));
+    EXPECT_FALSE(isInf(bitCast<float>(1u << 31 | 0xffu << 23 | 0x7fffffu)));
+    EXPECT_FALSE(isInf(bitCast<float>(0xfeu << 23 | 0x7fffffu)));
+    EXPECT_FALSE(isInf(bitCast<float>(1u << 31 | 0xfeu << 23 | 0x7fffffu)));
+}
+
 }
 

src/compiler/translator/IntermNode.cpp

@@ -1698,6 +1698,60 @@ TConstantUnion *TIntermConstantUnion::foldUnaryWithSameReturnType(TOperator op,
                 "Unary operation not folded into constant");
             return nullptr;
 
+          case EOpIsNan:
+            if (getType().getBasicType() == EbtFloat)
+            {
+                resultArray[i].setBConst(gl::isNaN(operandArray[0].getFConst()));
+                break;
+            }
+            infoSink.info.message(EPrefixInternalError, getLine(), "Unary operation not folded into constant");
+            return nullptr;
+
+          case EOpIsInf:
+            if (getType().getBasicType() == EbtFloat)
+            {
+                resultArray[i].setBConst(gl::isInf(operandArray[0].getFConst()));
+                break;
+            }
+            infoSink.info.message(EPrefixInternalError, getLine(), "Unary operation not folded into constant");
+            return nullptr;
+
+          case EOpFloatBitsToInt:
+            if (getType().getBasicType() == EbtFloat)
+            {
+                resultArray[i].setIConst(gl::bitCast<int32_t>(operandArray[0].getFConst()));
+                break;
+            }
+            infoSink.info.message(EPrefixInternalError, getLine(), "Unary operation not folded into constant");
+            return nullptr;
+
+          case EOpFloatBitsToUint:
+            if (getType().getBasicType() == EbtFloat)
+            {
+                resultArray[i].setUConst(gl::bitCast<uint32_t>(operandArray[0].getFConst()));
+                break;
+            }
+            infoSink.info.message(EPrefixInternalError, getLine(), "Unary operation not folded into constant");
+            return nullptr;
+
+          case EOpIntBitsToFloat:
+            if (getType().getBasicType() == EbtInt)
+            {
+                resultArray[i].setFConst(gl::bitCast<float>(operandArray[0].getIConst()));
+                break;
+            }
+            infoSink.info.message(EPrefixInternalError, getLine(), "Unary operation not folded into constant");
+            return nullptr;
+
+          case EOpUintBitsToFloat:
+            if (getType().getBasicType() == EbtUInt)
+            {
+                resultArray[i].setFConst(gl::bitCast<float>(operandArray[0].getUConst()));
+                break;
+            }
+            infoSink.info.message(EPrefixInternalError, getLine(), "Unary operation not folded into constant");
+            return nullptr;
+
           case EOpExp:
             if (!foldFloatTypeUnary(operandArray[i], &expf, infoSink, &resultArray[i]))
               return nullptr;