Support samplerBuffer as function parameters in HLSL.

reference/shaders-hlsl/vert/sampler-buffers.vert

@@ -8,9 +8,14 @@ struct SPIRV_Cross_Output
     float4 gl_Position : SV_Position;
 };
 
+float4 sample_from_function(Buffer<float4> s0, Buffer<int4> s1, Buffer<uint4> s2)
+{
+    return (s0.Load(20) + asfloat(s1.Load(40))) + asfloat(s2.Load(60));
+}
+
 void vert_main()
 {
-    gl_Position = (uFloatSampler.Load(20) + asfloat(uIntSampler.Load(40))) + asfloat(uUintSampler.Load(60));
+    gl_Position = sample_from_function(uFloatSampler, uIntSampler, uUintSampler);
 }
 
 SPIRV_Cross_Output main()

shaders-hlsl/vert/sampler-buffers.vert

@@ -4,10 +4,14 @@ layout(binding = 1) uniform samplerBuffer uFloatSampler;
 layout(binding = 2) uniform isamplerBuffer uIntSampler;
 layout(binding = 3) uniform usamplerBuffer uUintSampler;
 
+vec4 sample_from_function(samplerBuffer s0, isamplerBuffer s1, usamplerBuffer s2)
+{
+	return texelFetch(s0, 20) +
+		intBitsToFloat(texelFetch(s1, 40)) +
+		uintBitsToFloat(texelFetch(s2, 60));
+}
+
 void main()
 {
-	gl_Position =
-		texelFetch(uFloatSampler, 20) +
-		intBitsToFloat(texelFetch(uIntSampler, 40)) +
-		uintBitsToFloat(texelFetch(uUintSampler, 60));
+	gl_Position = sample_from_function(uFloatSampler, uIntSampler, uUintSampler);
 }

spirv_hlsl.cpp

@@ -1032,7 +1032,7 @@ string CompilerHLSL::to_func_call_arg(uint32_t id)
 		// We don't have to consider combined image samplers here via OpSampledImage because
 		// those variables cannot be passed as arguments to functions.
 		// Only global SampledImage variables may be used as arguments.
-		if (type.basetype == SPIRType::SampledImage)
+		if (type.basetype == SPIRType::SampledImage && type.image.dim != DimBuffer)
 			arg_str += ", " + to_sampler_expression(id);
 	}
 
@@ -1080,11 +1080,10 @@ void CompilerHLSL::emit_function_prototype(SPIRFunction &func, uint64_t return_f
 
 		// Flatten a combined sampler to two separate arguments in modern HLSL.
 		auto &arg_type = get<SPIRType>(arg.type);
-		if (options.shader_model > 30 && arg_type.basetype == SPIRType::SampledImage)
+		if (options.shader_model > 30 && arg_type.basetype == SPIRType::SampledImage && arg_type.image.dim != DimBuffer)
 		{
 			// Manufacture automatic sampler arg for SampledImage texture
 			decl += ", ";
-			if (arg_type.basetype == SPIRType::SampledImage)
 			decl += join(arg_type.image.depth ? "SamplerComparisonState " : "SamplerState ",
 			             to_sampler_expression(arg.id));
 		}