glslang representing literal constants with double precision, so 1.0e…

…40 and 1.0e-50 are normal values.

Shader1：
precision highp float;
out vec4 my_FragColor;
void main()
{
// Out-of-range floats should overflow to infinity
// GLSL ES 3.00.6 section 4.1.4 Floats:
// "If the value of the floating point number is too large (small) to be stored as a single precision value, it is converted to positive (negative) infinity"
float correct = isinf(1.0e40) ? 1.0 : 0.0;
my_FragColor = vec4(0.0, correct, 0.0, 1.0);
}

precision highp float;
out vec4 my_FragColor;
void main()
{
// GLSL ES 3.00.6 section 4.1.4 Floats:
// "A value with a magnitude too small to be represented as a mantissa and exponent is converted to zero."
// 1.0e-50 is small enough that it can't even be stored as subnormal.
float correct = (1.0e-50 == 0.0) ? 1.0 : 0.0;
my_FragColor = vec4(0.0, correct, 0.0, 1.0);
}
KHR-GLES3.number_parsing.float_out_of_range_as_infinity

glslang/MachineIndependent/Intermediate.cpp

@@ -2589,7 +2589,17 @@ TIntermConstantUnion* TIntermediate::addConstantUnion(bool b, const TSourceLoc&
 TIntermConstantUnion* TIntermediate::addConstantUnion(double d, TBasicType baseType, const TSourceLoc& loc, bool literal) const
 {
     assert(baseType == EbtFloat || baseType == EbtDouble || baseType == EbtFloat16);
-
+    if (baseType == EbtFloat)
+        d = (float)d;
+    else if (baseType == EbtFloat16 && !IsInfinity(d) && !IsNan(d)) {
+        int exponent = (((*(unsigned long long*)&d) >> 52) & 0x7ff) - 1023;
+        if (exponent < -14)
+            d = 0.0;
+        else if (exponent > 15){
+            (*(unsigned long long*)&d) &= ~((((unsigned long long)1) << 52) - 1);
+            (*(unsigned long long*)&d) |= ((unsigned long long)0x7ff) << 52;
+        }
+    }
     TConstUnionArray unionArray(1);
     unionArray[0].setDConst(d);