Commit 8dc597ab authored by Lee Salzman's avatar Lee Salzman
Browse files

Bug 1791495 - Check for zero sqrt on ARM. r=jrmuizel, a=RyanVM 

For SWGL on ARM, we implement sqrt(N) as N * inversesqrt(N). This means we don't
properly handle zero unless we explicitly check for it. Otherwise, a NaN ends up
getting produced erroneously.

Differential Revision: https://phabricator.services.mozilla.com/D161107
parent 38d7f042

gfx/wr/swgl/src/glsl.h

+9 −6
Original line number Diff line number Diff line
@@ -127,6 +127,11 @@ SI U32 if_then_else(I32 c, U32 t, U32 e) { 
  return bit_cast<U32>((c & bit_cast<I32>(t)) | (~c & bit_cast<I32>(e)));

}



// Cheaper version of if_then_else that returns Float(0) if condition is false.

SI Float if_then(I32 c, Float t) {

  return bit_cast<Float>(c & bit_cast<I32>(t));

}



SI Float if_then_else(I32 c, Float t, Float e) {

  return bit_cast<Float>((c & bit_cast<I32>(t)) | (~c & bit_cast<I32>(e)));

}
@@ -195,7 +200,7 @@ SI Float sqrt(Float v) { 
  Float e = vrsqrteq_f32(v);

  e *= vrsqrtsq_f32(v, e * e);

  e *= vrsqrtsq_f32(v, e * e);

  return v * e;

  return if_then(v != Float(0.0f), v * e);

#else

  return (Float){sqrtf(v.x), sqrtf(v.y), sqrtf(v.z), sqrtf(v.w)};

#endif
@@ -246,9 +251,7 @@ SI Float inversesqrt(Float v) { 


SI float step(float edge, float x) { return float(x >= edge); }



SI Float step(Float edge, Float x) {

  return if_then_else(x < edge, Float(0), Float(1));

}

SI Float step(Float edge, Float x) { return if_then(x >= edge, Float(1)); }



/*

enum RGBA {
@@ -682,7 +685,7 @@ float floor(float a) { return floorf(a); } 


Float floor(Float v) {

  Float roundtrip = cast(cast(v));

  return roundtrip - if_then_else(roundtrip > v, Float(1), Float(0));

  return roundtrip - if_then(roundtrip > v, Float(1));

}



vec2 floor(vec2 v) { return vec2(floor(v.x), floor(v.y)); }
@@ -697,7 +700,7 @@ float ceil(float a) { return ceilf(a); } 


Float ceil(Float v) {

  Float roundtrip = cast(cast(v));

  return roundtrip + if_then_else(roundtrip < v, Float(1), Float(0));

  return roundtrip + if_then(roundtrip < v, Float(1));

}



// Round to nearest even