HLSL: Add support for treating NonWritable UAV texture as SRV instead.

1 files changed, 32 insertions, 5 deletions

diff --git a/spirv_hlsl.cpp b/spirv_hlsl.cpp
index 8639f201..29846c76 100644
--- a/spirv_hlsl.cpp
+++ b/spirv_hlsl.cpp
@@ -210,6 +210,8 @@ string CompilerHLSL::image_type_hlsl_modern(const SPIRType &type, uint32_t id)
 	bool typed_load = false;
 	uint32_t components = 4;
 
+	bool force_image_srv = hlsl_options.nonwritable_uav_texture_as_srv && has_decoration(id, DecorationNonWritable);
+
 	switch (type.image.dim)
 	{
 	case Dim1D:
@@ -239,7 +241,14 @@ string CompilerHLSL::image_type_hlsl_modern(const SPIRType &type, uint32_t id)
 			if (interlocked_resources.count(id))
 				return join("RasterizerOrderedBuffer<", image_format_to_type(type.image.format, imagetype.basetype),
 				            ">");
-			return join("RWBuffer<", image_format_to_type(type.image.format, imagetype.basetype), ">");
+
+			typed_load = !force_image_srv && type.image.sampled == 2;
+
+			const char *rw = force_image_srv ? "" : "RW";
+			return join(rw, "Buffer<",
+			            typed_load ? image_format_to_type(type.image.format, imagetype.basetype) :
+			                         join(type_to_glsl(imagetype), components),
+			            ">");
 		}
 		else
 			SPIRV_CROSS_THROW("Sampler buffers must be either sampled or unsampled. Cannot deduce in runtime.");
@@ -252,9 +261,14 @@ string CompilerHLSL::image_type_hlsl_modern(const SPIRType &type, uint32_t id)
 	}
 	const char *arrayed = type.image.arrayed ? "Array" : "";
 	const char *ms = type.image.ms ? "MS" : "";
-	const char *rw = typed_load ? "RW" : "";
+	const char *rw = typed_load && !force_image_srv ? "RW" : "";
+
+	if (force_image_srv)
+		typed_load = false;
+
 	if (typed_load && interlocked_resources.count(id))
 		rw = "RasterizerOrdered";
+
 	return join(rw, "Texture", dim, ms, arrayed, "<",
 	            typed_load ? image_format_to_type(type.image.format, imagetype.basetype) :
 	                         join(type_to_glsl(imagetype), components),
@@ -2971,8 +2985,16 @@ string CompilerHLSL::to_resource_binding(const SPIRVariable &var)
 	case SPIRType::Image:
 		if (type.image.sampled == 2 && type.image.dim != DimSubpassData)
 		{
-			space = 'u'; // UAV
-			resource_flags = HLSL_BINDING_AUTO_UAV_BIT;
+			if (has_decoration(var.self, DecorationNonWritable) && hlsl_options.nonwritable_uav_texture_as_srv)
+			{
+				space = 't'; // SRV
+				resource_flags = HLSL_BINDING_AUTO_SRV_BIT;
+			}
+			else
+			{
+				space = 'u'; // UAV
+				resource_flags = HLSL_BINDING_AUTO_UAV_BIT;
+			}
 		}
 		else
 		{
@@ -4813,7 +4835,12 @@ void CompilerHLSL::emit_instruction(const Instruction &instruction)
 			imgexpr = join(to_expression(ops[2]), "[", to_expression(ops[3]), "]");
 			// The underlying image type in HLSL depends on the image format, unlike GLSL, where all images are "vec4",
 			// except that the underlying type changes how the data is interpreted.
-			if (var && !subpass_data)
+
+			bool force_srv =
+			    hlsl_options.nonwritable_uav_texture_as_srv && var && has_decoration(var->self, DecorationNonWritable);
+			pure = force_srv;
+
+			if (var && !subpass_data && !force_srv)
 				imgexpr = remap_swizzle(get<SPIRType>(result_type),
 				                        image_format_to_components(get<SPIRType>(var->basetype).image.format), imgexpr);
 		}