SPIRV-Cross/reference/shaders-hlsl/frag/sampler-array.frag
Hans-Kristian Arntzen acae607703 Register implied expression reads in OpLoad/OpAccessChain.
This is required to avoid relying on complex sub-expression elimination
in compilers, and generates cleaner code.

The problem case is if a complex expression is used in an access chain,
like:

Composite comp = buffer[texture(...)];
vec4 a = comp.a + comp.b + comp.c;

Before, we did not have common subexpression tracking for
OpLoad/OpAccessChain, so we easily ended up with code like:

vec4 a = buffer[texture(...)].a + buffer[texture(...)].b + buffer[texture(...)].c;

A good compiler will optimize this, but we should not rely on it, and
forcing texture(...) to a temporary also looks better.

The solution is to add a vector "implied_expression_reads", which works
similarly to expression_dependencies. We also need an extra mechanism in
to_expression which lets us skip expression read checking and do it
later. E.g. for expr -> access chain -> load, we should only trigger
a read of expr when using the loaded expression.
2019-01-04 14:56:12 +01:00

45 lines
1.2 KiB
GLSL

Texture2D<float4> uCombined[4] : register(t0);
SamplerState _uCombined_sampler[4] : register(s0);
Texture2D<float4> uTex[4] : register(t4);
SamplerState uSampler[4] : register(s8);
RWTexture2D<float4> uImage[8] : register(u12);
static float4 gl_FragCoord;
static float2 vTex;
static int vIndex;
struct SPIRV_Cross_Input
{
float2 vTex : TEXCOORD0;
nointerpolation int vIndex : TEXCOORD1;
float4 gl_FragCoord : SV_Position;
};
float4 sample_in_function(Texture2D<float4> samp, SamplerState _samp_sampler)
{
return samp.Sample(_samp_sampler, vTex);
}
float4 sample_in_function2(Texture2D<float4> tex, SamplerState samp)
{
return tex.Sample(samp, vTex);
}
void frag_main()
{
float4 color = uCombined[vIndex].Sample(_uCombined_sampler[vIndex], vTex);
color += uTex[vIndex].Sample(uSampler[vIndex], vTex);
int _72 = vIndex + 1;
color += sample_in_function(uCombined[_72], _uCombined_sampler[_72]);
color += sample_in_function2(uTex[vIndex + 1], uSampler[vIndex + 1]);
uImage[vIndex][int2(gl_FragCoord.xy)] = color;
}
void main(SPIRV_Cross_Input stage_input)
{
gl_FragCoord = stage_input.gl_FragCoord;
vTex = stage_input.vTex;
vIndex = stage_input.vIndex;
frag_main();
}