06b84efcb3
We now insert helper functions which defer the assignment of out- parameters back into their original variables to the end of the function call. This allows us to match the semantics listed the GLSL spec in section 6.1.1: "All arguments are evaluated at call time, exactly once, in order, from left to right. [...] Evaluation of an out parameter results in an l-value that is used to copy out a value when the function returns. Evaluation of an inout parameter results in both a value and an l-value; the value is copied to the formal parameter at call time and the lvalue is used to copy out a value when the function returns." This technique also allows us to support swizzled out-parameters in Metal, by reading the swizzle into a temp variable, calling the original function, and then re-assigning the result back into the original swizzle expression. At present, we don't deduplicate these helper functions, so in theory there could be a fair amount of redundant code generated if a function with out parameters is called many times in a row. The cost of properly deduplicating them is probably larger than the benefit in the 99% case. Change-Id: Iefc922ac9e2b24ef2ff1e9dacb17a735a75ec8ea Bug: skia:10855, skia:11052 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/341162 Commit-Queue: Brian Osman <brianosman@google.com> Reviewed-by: Brian Osman <brianosman@google.com> Auto-Submit: John Stiles <johnstiles@google.com>
42 lines
1.4 KiB
Metal
42 lines
1.4 KiB
Metal
#include <metal_stdlib>
|
|
#include <simd/simd.h>
|
|
using namespace metal;
|
|
struct Inputs {
|
|
};
|
|
struct Outputs {
|
|
float4 sk_FragColor [[color(0)]];
|
|
};
|
|
struct Globals {
|
|
float2 glob;
|
|
};
|
|
float4 fn(thread Outputs* _out, thread Globals* _globals, float a, thread float2& b, thread float2& c, thread float3& d);
|
|
float4 _skOutParamHelper0_fn(thread Outputs* _out, thread Globals* _globals, float _var0, thread float3& b, thread float2& glob, thread float3x3& d) {
|
|
float2 _var1;
|
|
float2 _var2 = glob.yx;
|
|
float3 _var3 = d[1].zyx;
|
|
float4 _skResult = fn(_out, _globals, _var0, _var1, _var2, _var3);
|
|
b.yz = _var1;
|
|
glob.yx = _var2;
|
|
d[1].zyx = _var3;
|
|
return _skResult;
|
|
}
|
|
|
|
float4 fn(thread Outputs* _out, thread Globals* _globals, float a, thread float2& b, thread float2& c, thread float3& d) {
|
|
a = _out->sk_FragColor.x + a;
|
|
b = _out->sk_FragColor.yz - _globals->glob.y;
|
|
c *= a;
|
|
d = _out->sk_FragColor.www / d;
|
|
return float4(a, b.x, c.y, d.x);
|
|
}
|
|
fragment Outputs fragmentMain(Inputs _in [[stage_in]], bool _frontFacing [[front_facing]], float4 _fragCoord [[position]]) {
|
|
Globals globalStruct{float2(1.0)};
|
|
thread Globals* _globals = &globalStruct;
|
|
(void)_globals;
|
|
Outputs _outputStruct;
|
|
thread Outputs* _out = &_outputStruct;
|
|
float3 b = float3(2.0);
|
|
float3x3 d = float3x3(4.0);
|
|
_out->sk_FragColor = _skOutParamHelper0_fn(_out, _globals, 1.0, b, _globals->glob, d);
|
|
return *_out;
|
|
}
|