Fix clamping of NaN values.

We pass integer uniforms as floating-point ones, which can cause an
exception when converting them to fixed-point values. For example an
integer value of -1 would be 0xFFFFFFFF which is Not-a-Number in
IEEE-754 floating-point and can't be cast to an integer.

In this case we don't actually care about the result because the fixed-
point number is only used by the fixed-function pipeline. A safe but
still fast way to compare floating-point numbers including NaNs is to
treat them as one's complement integers, which can easily be converted
into two's complement representation.

Also rename bitCast<> to bit_cast<> to match the C++20 function.

Change-Id: Id588d25ab70d31eda2800c24a8df539d6a3411d4
Reviewed-on: https://swiftshader-review.googlesource.com/c/21708
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/src/OpenGL/compiler/Intermediate.cpp b/src/OpenGL/compiler/Intermediate.cpp
index ee77a2f..9f68dc7 100644
--- a/src/OpenGL/compiler/Intermediate.cpp
+++ b/src/OpenGL/compiler/Intermediate.cpp
@@ -1974,7 +1974,7 @@
 				case EOpFloatBitsToInt:
 					switch(basicType) {
 					case EbtFloat:
-						tempConstArray[i].setIConst(sw::bitCast<int>(unionArray[i].getFConst()));
+						tempConstArray[i].setIConst(sw::bit_cast<int>(unionArray[i].getFConst()));
 						type.setBasicType(EbtInt);
 						break;
 					default:
@@ -1986,7 +1986,7 @@
 				case EOpFloatBitsToUint:
 					switch(basicType) {
 					case EbtFloat:
-						tempConstArray[i].setUConst(sw::bitCast<unsigned int>(unionArray[i].getFConst()));
+						tempConstArray[i].setUConst(sw::bit_cast<unsigned int>(unionArray[i].getFConst()));
 						type.setBasicType(EbtUInt);
 						break;
 					default:
@@ -1997,7 +1997,7 @@
 				case EOpIntBitsToFloat:
 					switch(basicType) {
 					case EbtInt:
-						tempConstArray[i].setFConst(sw::bitCast<float>(unionArray[i].getIConst()));
+						tempConstArray[i].setFConst(sw::bit_cast<float>(unionArray[i].getIConst()));
 						type.setBasicType(EbtFloat);
 						break;
 					default:
@@ -2008,7 +2008,7 @@
 				case EOpUintBitsToFloat:
 					switch(basicType) {
 					case EbtUInt:
-						tempConstArray[i].setFConst(sw::bitCast<float>(unionArray[i].getUConst()));
+						tempConstArray[i].setFConst(sw::bit_cast<float>(unionArray[i].getUConst()));
 						type.setBasicType(EbtFloat);
 						break;
 					default: