Merge pull request #360 from KhronosGroup/vulkan-glsl-desktop-mediump

Support mediump in desktop Vulkan GLSL.

reference/opt/shaders/vulkan/frag/desktop-mediump.vk.frag

@@ -0,0 +1,12 @@
+#version 450
+
+layout(location = 0) out vec4 FragColor;
+layout(location = 0) in vec4 F;
+layout(location = 1) flat in ivec4 I;
+layout(location = 2) flat in uvec4 U;
+
+void main()
+{
+    FragColor = (F + vec4(I)) + vec4(U);
+}
+

reference/opt/shaders/vulkan/frag/desktop-mediump.vk.frag.vk

@@ -0,0 +1,12 @@
+#version 450
+
+layout(location = 0) out mediump vec4 FragColor;
+layout(location = 0) in mediump vec4 F;
+layout(location = 1) flat in mediump ivec4 I;
+layout(location = 2) flat in mediump uvec4 U;
+
+void main()
+{
+    FragColor = (F + vec4(I)) + vec4(U);
+}
+

reference/shaders/vulkan/frag/desktop-mediump.vk.frag

@@ -0,0 +1,12 @@
+#version 450
+
+layout(location = 0) out vec4 FragColor;
+layout(location = 0) in vec4 F;
+layout(location = 1) flat in ivec4 I;
+layout(location = 2) flat in uvec4 U;
+
+void main()
+{
+    FragColor = (F + vec4(I)) + vec4(U);
+}
+

reference/shaders/vulkan/frag/desktop-mediump.vk.frag.vk

@@ -0,0 +1,12 @@
+#version 450
+
+layout(location = 0) out mediump vec4 FragColor;
+layout(location = 0) in mediump vec4 F;
+layout(location = 1) flat in mediump ivec4 I;
+layout(location = 2) flat in mediump uvec4 U;
+
+void main()
+{
+    FragColor = (F + vec4(I)) + vec4(U);
+}
+

shaders/vulkan/frag/desktop-mediump.vk.frag

@@ -0,0 +1,11 @@
+#version 450
+
+layout(location = 0) in mediump vec4 F;
+layout(location = 1) flat in mediump ivec4 I;
+layout(location = 2) flat in mediump uvec4 U;
+layout(location = 0) out mediump vec4 FragColor;
+
+void main()
+{
+	FragColor = F + vec4(I) + vec4(U);
+}

spirv_glsl.cpp

@@ -368,6 +368,9 @@ string CompilerGLSL::compile()
 	// Force a classic "C" locale, reverts when function returns
 	ClassicLocale classic_locale;
 
+	if (options.vulkan_semantics)
+		backend.allow_precision_qualifiers = true;
+
 	// Scan the SPIR-V to find trivial uses of extensions.
 	find_static_extensions();
 	fixup_image_load_store_access();
@@ -6860,16 +6863,16 @@ void CompilerGLSL::emit_struct_member(const SPIRType &type, uint32_t member_type
 
 const char *CompilerGLSL::flags_to_precision_qualifiers_glsl(const SPIRType &type, uint64_t flags)
 {
+	// Structs do not have precision qualifiers, neither do doubles (desktop only anyways, so no mediump/highp).
+	if (type.basetype != SPIRType::Float && type.basetype != SPIRType::Int && type.basetype != SPIRType::UInt &&
+	    type.basetype != SPIRType::Image && type.basetype != SPIRType::SampledImage &&
+	    type.basetype != SPIRType::Sampler)
+		return "";
+
 	if (options.es)
 	{
 		auto &execution = get_entry_point();
 
-		// Structs do not have precision qualifiers, neither do doubles (desktop only anyways, so no mediump/highp).
-		if (type.basetype != SPIRType::Float && type.basetype != SPIRType::Int && type.basetype != SPIRType::UInt &&
-		    type.basetype != SPIRType::Image && type.basetype != SPIRType::SampledImage &&
-		    type.basetype != SPIRType::Sampler)
-			return "";
-
 		if (flags & (1ull << DecorationRelaxedPrecision))
 		{
 			bool implied_fmediump = type.basetype == SPIRType::Float &&
@@ -6897,6 +6900,19 @@ const char *CompilerGLSL::flags_to_precision_qualifiers_glsl(const SPIRType &typ
 			return implied_fhighp || implied_ihighp ? "" : "highp ";
 		}
 	}
+	else if (backend.allow_precision_qualifiers)
+	{
+		// Vulkan GLSL supports precision qualifiers, even in desktop profiles, which is convenient.
+		// The default is highp however, so only emit mediump in the rare case that a shader has these.
+		if (flags & (1ull << DecorationRelaxedPrecision))
+		{
+			bool can_use_mediump =
+			    type.basetype == SPIRType::Float || type.basetype == SPIRType::Int || type.basetype == SPIRType::UInt;
+			return can_use_mediump ? "mediump " : "";
+		}
+		else
+			return "";
+	}
 	else
 		return "";
 }

spirv_glsl.hpp

@@ -319,6 +319,7 @@ protected:
 		bool native_row_major_matrix = true;
 		bool use_constructor_splatting = true;
 		bool boolean_mix_support = true;
+		bool allow_precision_qualifiers = false;
 	} backend;
 
 	void emit_struct(SPIRType &type);

test_shaders.sh

@@ -7,9 +7,10 @@ export PATH="./external/glslang-build/StandAlone:./external/spirv-tools-build/to
 echo "Using glslangValidation in: $(which glslangValidator)."
 echo "Using spirv-opt in: $(which spirv-opt)."
 
-./test_shaders.py shaders
-./test_shaders.py shaders --opt
-./test_shaders.py shaders-msl --msl
-./test_shaders.py shaders-msl --msl --opt
-./test_shaders.py shaders-hlsl --hlsl
-./test_shaders.py shaders-hlsl --hlsl --opt
+./test_shaders.py shaders --update || exit 1
+./test_shaders.py shaders --update --opt || exit 1
+./test_shaders.py shaders-msl --msl --update || exit 1
+./test_shaders.py shaders-msl --msl --update --opt || exit 1
+./test_shaders.py shaders-hlsl --hlsl --update || exit 1
+./test_shaders.py shaders-hlsl --hlsl --update --opt || exit 1
+

update_test_shaders.sh

@@ -7,9 +7,10 @@ export PATH="./external/glslang-build/StandAlone:./external/spirv-tools-build/to
 echo "Using glslangValidation in: $(which glslangValidator)."
 echo "Using spirv-opt in: $(which spirv-opt)."
 
-./test_shaders.py shaders --update
-./test_shaders.py shaders --update --opt
-./test_shaders.py shaders-msl --msl --update
-./test_shaders.py shaders-msl --msl --update --opt
-./test_shaders.py shaders-hlsl --hlsl --update
-./test_shaders.py shaders-hlsl --hlsl --update --opt
+./test_shaders.py shaders --update || exit 1
+./test_shaders.py shaders --update --opt || exit 1
+./test_shaders.py shaders-msl --msl --update || exit 1
+./test_shaders.py shaders-msl --msl --update --opt || exit 1
+./test_shaders.py shaders-hlsl --hlsl --update || exit 1
+./test_shaders.py shaders-hlsl --hlsl --update --opt || exit 1
+