skia2/tests/sksl/shared/OutParamsTricky.metal
John Stiles ec24154521 Fix SPIR-V bug with swizzled out parameters.
The CL at http://review.skia.org/366399 introduced a bug with
LValue::getPointer. Specifically, getPointer used to return zero when
no pointer is available. (This happens when the LValue is a swizzle.)
That CL changed the error code to -1. However, it did not fix up all
the call sites that checked the return value of getPointer().

This CL fixes up those call sites to use -1 consistently, and adds
TODOs in spots which do not check the result from getPointer() at all
(instead assuming it cannot fail). This will allow swizzled out-
parameters to work in SPIR-V as they did before. (Except in intrinsics,
where they seem to have been broken all along, but those are now marked
with a TODO at least.)

Note that we still do not fully emulate GLSL semantics for out
parameters, as out-parameters should only be copied back to the original
variable at the end of the function call to be fully GLSL compliant.

(This CL also replaces a tuple with a named struct for readability.)

Change-Id: I708dc7a69296a4244ba9ceb85c3e68d1f331bbc9
Bug: skia:11052
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368618
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2021-02-12 15:21:27 +00:00

44 lines
1.3 KiB
Metal

#include <metal_stdlib>
#include <simd/simd.h>
using namespace metal;
struct Uniforms {
float4 colorGreen;
float4 colorRed;
};
struct Inputs {
};
struct Outputs {
float4 sk_FragColor [[color(0)]];
};
float2 tricky(float x, float y, thread float2& color, float z);
float2 _skOutParamHelper0_tricky(float _var0, float _var1, thread float4& color, float _var3) {
float2 _var2 = color.xz;
float2 _skResult = tricky(_var0, _var1, _var2, _var3);
color.xz = _var2;
return _skResult;
}
void func(thread float4& color);
void _skOutParamHelper1_func(thread float4& result) {
float4 _var0 = result;
func(_var0);
result = _var0;
}
float2 tricky(float x, float y, thread float2& color, float z) {
color.xy = color.yx;
return float2(x + y, z);
}
void func(thread float4& color) {
float2 t = _skOutParamHelper0_tricky(1.0, 2.0, color, 5.0);
color.yw = t;
}
fragment Outputs fragmentMain(Inputs _in [[stage_in]], constant Uniforms& _uniforms [[buffer(0)]], bool _frontFacing [[front_facing]], float4 _fragCoord [[position]]) {
Outputs _out;
(void)_out;
float4 result = float4(0.0, 1.0, 2.0, 3.0);
_skOutParamHelper1_func(result);
_out.sk_FragColor = all(result == float4(2.0, 3.0, 0.0, 5.0)) ? _uniforms.colorGreen : _uniforms.colorRed;
return _out;
}