Fix case where samplerBuffer is emitted without combined sampler.

reference/shaders/asm/frag/sampler-buffer-without-sampler.asm.frag

@@ -0,0 +1,20 @@
+#version 450
+
+layout(rgba32f) uniform writeonly imageBuffer RWTex;
+uniform samplerBuffer Tex;
+
+layout(location = 0) out vec4 _entryPointOutput;
+
+vec4 _main()
+{
+    vec4 storeTemp = vec4(1.0, 2.0, 3.0, 4.0);
+    imageStore(RWTex, 20, storeTemp);
+    return texelFetch(Tex, 10);
+}
+
+void main()
+{
+    vec4 _28 = _main();
+    _entryPointOutput = _28;
+}
+

shaders/asm/frag/sampler-buffer-without-sampler.asm.frag

@@ -0,0 +1,59 @@
+; SPIR-V
+; Version: 1.0
+; Generator: Khronos Glslang Reference Front End; 1
+; Bound: 36
+; Schema: 0
+               OpCapability Shader
+               OpCapability SampledBuffer
+          %1 = OpExtInstImport "GLSL.std.450"
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %main "main" %_entryPointOutput
+               OpExecutionMode %main OriginUpperLeft
+               OpName %main "main"
+               OpName %_main_ "@main("
+               OpName %storeTemp "storeTemp"
+               OpName %RWTex "RWTex"
+               OpName %Tex "Tex"
+               OpName %_entryPointOutput "@entryPointOutput"
+               OpDecorate %RWTex DescriptorSet 0
+               OpDecorate %Tex DescriptorSet 0
+               OpDecorate %_entryPointOutput Location 0
+       %void = OpTypeVoid
+          %3 = OpTypeFunction %void
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+          %8 = OpTypeFunction %v4float
+%_ptr_Function_v4float = OpTypePointer Function %v4float
+         %13 = OpConstant %float 1
+         %14 = OpConstant %float 2
+         %15 = OpConstant %float 3
+         %16 = OpConstant %float 4
+         %17 = OpConstantComposite %v4float %13 %14 %15 %16
+         %18 = OpTypeImage %float Buffer 0 0 0 2 Rgba32f
+%_ptr_UniformConstant_18 = OpTypePointer UniformConstant %18
+      %RWTex = OpVariable %_ptr_UniformConstant_18 UniformConstant
+        %int = OpTypeInt 32 1
+         %23 = OpConstant %int 20
+         %25 = OpTypeImage %float Buffer 0 0 0 1 Rgba32f
+%_ptr_UniformConstant_25 = OpTypePointer UniformConstant %25
+        %Tex = OpVariable %_ptr_UniformConstant_25 UniformConstant
+         %29 = OpConstant %int 10
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+%_entryPointOutput = OpVariable %_ptr_Output_v4float Output
+       %main = OpFunction %void None %3
+          %5 = OpLabel
+         %35 = OpFunctionCall %v4float %_main_
+               OpStore %_entryPointOutput %35
+               OpReturn
+               OpFunctionEnd
+     %_main_ = OpFunction %v4float None %8
+         %10 = OpLabel
+  %storeTemp = OpVariable %_ptr_Function_v4float Function
+               OpStore %storeTemp %17
+         %21 = OpLoad %18 %RWTex
+         %24 = OpLoad %v4float %storeTemp
+               OpImageWrite %21 %23 %24
+         %28 = OpLoad %25 %Tex
+         %30 = OpImageFetch %v4float %28 %29
+               OpReturnValue %30
+               OpFunctionEnd

spirv_cross.cpp

@@ -1411,7 +1411,6 @@ void Compiler::parse(const Instruction &instruction)
 		break;
 	}
 
-	// Not really used.
 	case OpTypeSampler:
 	{
 		uint32_t id = ops[0];

spirv_glsl.cpp

@@ -996,7 +996,8 @@ string CompilerGLSL::layout_for_variable(const SPIRVariable &var)
 		attr.push_back(ssbo_is_std430_packing(type) ? "std430" : "std140");
 
 	// For images, the type itself adds a layout qualifer.
-	if (type.basetype == SPIRType::Image)
+	// Only emit the format for storage images.
+	if (type.basetype == SPIRType::Image && type.image.sampled == 2)
 	{
 		const char *fmt = format_to_glsl(type.image.format);
 		if (fmt)
@@ -1597,9 +1598,11 @@ void CompilerGLSL::emit_resources()
 			// If we're remapping separate samplers and images, only emit the combined samplers.
 			if (skip_separate_image_sampler)
 			{
+				// Sampler buffers are always used without a sampler, and they will also work in regular GL.
+				bool sampler_buffer = type.basetype == SPIRType::Image && type.image.dim == DimBuffer;
 				bool separate_image = type.basetype == SPIRType::Image && type.image.sampled == 1;
 				bool separate_sampler = type.basetype == SPIRType::Sampler;
-				if (separate_image || separate_sampler)
+				if (!sampler_buffer && (separate_image || separate_sampler))
 					continue;
 			}
 
@@ -5918,7 +5921,13 @@ string CompilerGLSL::image_type_glsl(const SPIRType &type)
 	// If we're emulating subpassInput with samplers, force sampler2D
 	// so we don't have to specify format.
 	if (type.basetype == SPIRType::Image && type.image.dim != DimSubpassData)
-		res += type.image.sampled == 2 ? "image" : "texture";
+	{
+		// Sampler buffers are always declared as samplerBuffer even though they might be separate images in the SPIR-V.
+		if (type.image.dim == DimBuffer && type.image.sampled == 1)
+			res += "sampler";
+		else
+			res += type.image.sampled == 2 ? "image" : "texture";
+	}
 	else
 		res += "sampler";
 
@@ -5992,7 +6001,6 @@ string CompilerGLSL::type_to_glsl(const SPIRType &type)
 		return image_type_glsl(type);
 
 	case SPIRType::Sampler:
-		// Not really used.
 		return "sampler";
 
 	case SPIRType::Void:

spirv_hlsl.cpp

@@ -61,7 +61,6 @@ string CompilerHLSL::type_to_glsl(const SPIRType &type)
 		return image_type_glsl(type);
 
 	case SPIRType::Sampler:
-		// Not really used.
 		return "sampler";
 
 	case SPIRType::Void:

spirv_msl.cpp

@@ -1851,7 +1851,6 @@ string CompilerMSL::type_to_glsl(const SPIRType &type)
 		return image_type_glsl(type);
 
 	case SPIRType::Sampler:
-		// Not really used.
 		return "sampler";
 
 	case SPIRType::Void: