SPV: Implement GLSL built-in bitcast functions.

Test/spv.bitCast.frag

@@ -0,0 +1,45 @@
+#version 450
+
+uniform int   i1;
+uniform ivec2 i2;
+uniform ivec3 i3;
+uniform ivec4 i4;
+
+uniform uint  u1;
+uniform uvec2 u2;
+uniform uvec3 u3;
+uniform uvec4 u4;
+
+uniform float f1;
+uniform vec2  f2;
+uniform vec3  f3;
+uniform vec4  f4;
+
+out vec4 fragColor;
+
+void main()
+{
+	ivec4 idata = ivec4(0);
+	idata.x     += floatBitsToInt(f1);
+	idata.xy    += floatBitsToInt(f2);
+	idata.xyz   += floatBitsToInt(f3);
+	idata       += floatBitsToInt(f4);
+
+	uvec4 udata = uvec4(0);
+	udata.x     += floatBitsToUint(f1);
+	udata.xy    += floatBitsToUint(f2);
+	udata.xyz   += floatBitsToUint(f3);
+	udata       += floatBitsToUint(f4);
+
+	vec4 fdata = vec4(0.0);
+	fdata.x     += intBitsToFloat(i1);
+	fdata.xy    += intBitsToFloat(i2);
+	fdata.xyz   += intBitsToFloat(i3);
+	fdata       += intBitsToFloat(i4);
+    fdata.x     += uintBitsToFloat(u1);
+	fdata.xy    += uintBitsToFloat(u2);
+	fdata.xyz   += uintBitsToFloat(u3);
+	fdata       += uintBitsToFloat(u4);
+
+    fragColor = (idata == udata) ? fdata : fdata + vec4(0.2);
+}