skia2/tests/sksl/blend/golden/BlendOverlayStandaloneSettings.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

14 lines
501 B
GLSL

out vec4 sk_FragColor;
float _blend_overlay_component(vec2 s, vec2 d) {
return 2.0 * d.x <= d.y ? (2.0 * s.x) * d.x : s.y * d.y - (2.0 * (d.y - d.x)) * (s.y - s.x);
}
in vec4 src;
in vec4 dst;
void main() {
vec4 _1_result = vec4(_blend_overlay_component(src.xw, dst.xw), _blend_overlay_component(src.yw, dst.yw), _blend_overlay_component(src.zw, dst.zw), src.w + (1.0 - src.w) * dst.w);
_1_result.xyz += dst.xyz * (1.0 - src.w) + src.xyz * (1.0 - dst.w);
sk_FragColor = _1_result;
}