skia2/tests/sksl/blend/golden/BlendSoftLight.glsl
John Stiles 77702f1704 Eliminate inliner temporary variables for top-level-exit functions.
When we determine that a function only contains a single return
statement and it is at the top level (i.e. not inside any scopes),
there is no need to create a temporary variable and store the
result expression into a variable. Instead, we can directly replace
the function-call expression with the return-statement's expression.

Unlike my previous solution, this does not require variable
declarations to be rewritten. The no-scopes limitation makes it
slightly less effective in theory, but in practice we still get
almost all of the benefit. The no-scope limitation bites us on
structures like

@if (true) {
    return x;
} else {
    return y;
}

Which will optimize away the if, but leave the scope:

{
    return x;
}

However, this is not a big deal; the biggest wins are single-line
helper functions like `guarded_divide` and `unpremul` which retain
the full benefit.

Change-Id: I7fbb725e65db021b9795c04c816819669815578f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345167
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
2020-12-17 20:37:21 +00:00

26 lines
989 B
GLSL

#version 400
out vec4 sk_FragColor;
float _soft_light_component(vec2 s, vec2 d) {
if (2.0 * s.x <= s.y) {
float _8_n = (d.x * d.x) * (s.y - 2.0 * s.x);
return (_8_n / d.y + (1.0 - d.y) * s.x) + d.x * ((-s.y + 2.0 * s.x) + 1.0);
} else if (4.0 * d.x <= d.y) {
float DSqd = d.x * d.x;
float DCub = DSqd * d.x;
float DaSqd = d.y * d.y;
float DaCub = DaSqd * d.y;
float _10_n = ((DaSqd * (s.x - d.x * ((3.0 * s.y - 6.0 * s.x) - 1.0)) + ((12.0 * d.y) * DSqd) * (s.y - 2.0 * s.x)) - (16.0 * DCub) * (s.y - 2.0 * s.x)) - DaCub * s.x;
return _10_n / DaSqd;
} else {
return ((d.x * ((s.y - 2.0 * s.x) + 1.0) + s.x) - sqrt(d.y * d.x) * (s.y - 2.0 * s.x)) - d.y * s.x;
}
}
in vec4 src;
in vec4 dst;
void main() {
sk_FragColor = dst.w == 0.0 ? src : vec4(_soft_light_component(src.xw, dst.xw), _soft_light_component(src.yw, dst.yw), _soft_light_component(src.zw, dst.zw), src.w + (1.0 - src.w) * dst.w);
}