Replace FastMulBySignOf() with CopySign()

ScriptableRenderPipeline/Core/CoreRP/ShaderLibrary/Common.hlsl

 // PositivePow remove this warning when you know the value is positive and avoid inf/NAN.
 TEMPLATE_2_REAL(PositivePow, base, power, return pow(max(abs(base), FLT_EPS), power))
 
-// Computes (FastSign(s) * x) using 2x VALU.
+// Composes a floating point value with the magnitude of 'x' and the sign of 's'.
-float FastMulBySignOf(float s, float x, bool ignoreNegZero = true)
+float CopySign(float x, float s, bool ignoreNegZero = true)
-        return (s >= 0) ? x : -x;
+        return (s >= 0) ? abs(x) : -abs(x);
-        return asfloat(signBit ^ asuint(x));
+        return asfloat(signBit | asuint(abs(x)));
-    return (s >= 0) ? x : -x;
+    return (s >= 0) ? abs(x) : -abs(x);
 #endif
 }
 
 // Note that the sign() function in HLSL implements signum, which returns 0 for 0.
 float FastSign(float s, bool ignoreNegZero = true)
 {
-    return FastMulBySignOf(s, 1.0, ignoreNegZero);
+    return CopySign(1.0, s, ignoreNegZero);
 }
 
 // Orthonormalizes the tangent frame using the Gram-Schmidt process.

ScriptableRenderPipeline/Core/CoreRP/ShaderLibrary/GeometricTools.hlsl

 bool SolveQuadraticEquation(float a, float b, float c, out float2 roots)
 {
     float d = b * b - 4 * a * c;
-    float q = -0.5 * (b + FastMulBySignOf(b, sqrt(d)));
+    float q = -0.5 * (b + CopySign(sqrt(d), b));
     roots   = float2(q / a, c / q);
 
     return (d >= 0);

ScriptableRenderPipeline/Core/CoreRP/ShaderLibrary/Packing.hlsl

 
     // Left side of the 2:1 rectangle for the negative hemisphere, right otherwise.
     // We also correct the aspect ratio from 2:1 to 1:1.
-    real s = (p.z >= 0) ? 0.5 : -0.5;
+    real s = CopySign(0.5, p.z);
 
     return real2(s * r, g);
 }