Honor explicit gather LOD with shared image mip selection

Co-authored-by: YuhiAida <21134775+YuhiAida@users.noreply.github.com>
Co-authored-by: BlackCAT <52720489+psnwd@users.noreply.github.com>
Co-authored-by: shadowbeat070 <70843316+shadowbeat070@users.noreply.github.com>
Co-authored-by: Senaxx <michelbeld@gmail.com>
Co-authored-by: Mac <me@itsmemac.com>
Co-authored-by: Ali Almohaya <AliAlmohaya@gmail.com>

src/graphics/shader/recompiler/ir/ShaderIR.h

@@ -114,7 +114,7 @@ struct BufferResource {
 	bool operator==(const BufferResource& other) const = default;
 };
 
-enum class ImageMipMode { None, DynamicStorage };
+enum class ImageMipMode { None, Dynamic };
 
 constexpr uint32_t ShaderImageIdentitySwizzle = 0x00000facu;
 
@@ -151,6 +151,7 @@ struct SamplerResource {
 	bool     force_point_filtering = false;
 	bool     depth_compare         = false;
 	bool     integer_border        = false;
+	bool     gather_lod            = false;
 
 	bool operator==(const SamplerResource& other) const = default;
 };

src/graphics/shader/recompiler/ir/opcodes/ValueOpcodes.inc

@@ -297,7 +297,7 @@ VALUE_OPCODE(ImageQueryLod, U32x4, ImageResource, SamplerResource, ImageAddress)
 VALUE_OPCODE(ImageRead, U32x4, ImageResource, ImageAddress, U1)
 VALUE_OPCODE(ImageWrite, Void, ImageResource, ImageAddress, U32x4, U1)
 VALUE_OPCODE(ImageSampleRaw, U32x4, ImageResource, SamplerResource, ImageAddress)
-VALUE_OPCODE(ImageGatherRaw, U32x4, ImageResource, SamplerResource, ImageAddress)
+VALUE_OPCODE(ImageGatherRaw, U32x4, ImageResource, SamplerResource, ImageAddress, U32, U32, U32, U32)
 VALUE_OPCODE(ImageAtomicCompareSwap32, U32, ImageResource, ImageAddress, U32, U32, U1)
 VALUE_OPCODE(ImageAtomicSwap32, U32, ImageResource, ImageAddress, U32, U1)
 VALUE_OPCODE(ImageAtomicIAdd32, U32, ImageResource, ImageAddress, U32, U1)

src/graphics/shader/recompiler/ir/passes/BindingLayout.cpp

@@ -126,7 +126,7 @@ void AllocateBindings(Program& program, uint32_t push_data_start_dword) {
 			EXIT("shader binding layout failed: image %u has an unmapped binding class", i);
 		}
 		auto&      resources = image_groups[group];
-		const auto dynamic   = program.info.images[i].mip_mode == ImageMipMode::DynamicStorage;
+		const auto dynamic   = program.info.images[i].mip_mode == ImageMipMode::Dynamic;
 		const auto count     = dynamic ? program.info.images[i].mip_count : 1u;
 		if (count == 0u || (!dynamic && program.info.images[i].mip_count != 1u)) {
 			EXIT("shader binding layout failed: image %u has invalid specialized mip count %u", i,

src/graphics/shader/recompiler/ir/passes/ResourceMaterialization.cpp

@@ -124,8 +124,8 @@ bool DescriptorIsCube(const DescriptorValue& descriptor) {
 	       Prospero::ImageType::kCube;
 }
 
-uint32_t StorageMipCount(const ImageResource& image, const DescriptorValue& descriptor) {
-	if (image.mip_mode != ImageMipMode::DynamicStorage || NullImageDescriptor(descriptor)) {
+uint32_t ImageMipCount(const ImageResource& image, const DescriptorValue& descriptor) {
+	if (image.mip_mode != ImageMipMode::Dynamic || NullImageDescriptor(descriptor)) {
 		return 1;
 	}
 	const auto base = (descriptor.dwords[3] >> 12u) & 0xfu;
@@ -435,10 +435,10 @@ static bool BuildResourceSpecialization(const ResourcePlan& program, ResourceSna
 		    (base.atomic && base.resource_class != ImageResourceClass::Storage)) {
 			return SpecializationFail(fmt::format("image resource {} has an invalid class", i));
 		}
-		image.mip_count = StorageMipCount(base, descriptor);
+		image.mip_count = ImageMipCount(base, descriptor);
 		if (image.mip_count == 0u) {
 			return SpecializationFail(
-			    fmt::format("storage image descriptor {} has an invalid mip range", i));
+			    fmt::format("image descriptor {} has an invalid mip range", i));
 		}
 		if (NullImageDescriptor(descriptor)) {
 			image.numeric_class = base.atomic ? Prospero::TextureNumericClass::Uint
@@ -1077,6 +1077,16 @@ bool MaterializeResources(const ResourcePlan& program, const SrtRuntime& runtime
 		if (!evaluate(program.info.samplers[i].source, snapshot.samplers[i])) {
 			return false;
 		}
+		if (program.info.samplers[i].gather_lod) {
+			const auto control = snapshot.samplers[i].dwords[2];
+			const auto filter = (control >> 26u) & 3u;
+			// MipNone always selects the base level. Explicit point gathers currently require
+			// encoded-zero primary and secondary bias; linear primary-mip selection is unsupported.
+			if (filter > 1u || (filter == 1u && (control & 0xfffffu) != 0u)) {
+				return SpecializationFail(
+				    "explicit-LOD gather requires mip filtering None or Point with zero LOD biases");
+			}
+		}
 	}
 	snapshot.user_data.assign(runtime.user_data.begin(), runtime.user_data.end());
 	return BuildResourceSpecialization(program, snapshot, specialization);

src/graphics/shader/recompiler/ir/passes/ResourceTracking.cpp

@@ -1727,9 +1727,11 @@ private:
 		const auto resource_class = ImageOpcodeInfoOf(op).resource_class;
 		const bool atomic64 = ImageOpcodeInfoOf(op).access == ImageAccess::Atomic &&
 		                      memory.data_bits == 64u;
-		const auto mip   = resource_class == ImageResourceClass::Storage && memory.image_has_mip
-		                       ? ImageMipMode::DynamicStorage
-		                       : ImageMipMode::None;
+		const bool dynamic_mip =
+		    (resource_class == ImageResourceClass::Storage && memory.image_has_mip) ||
+		    (op == ValueOpcode::ImageGatherRaw &&
+		     (memory.image_sample_flags & Decoder::ImageSampleFlagLod) != 0u);
+		const auto mip = dynamic_mip ? ImageMipMode::Dynamic : ImageMipMode::None;
 		const bool depth = (memory.image_sample_flags & Decoder::ImageSampleFlagCompare) != 0;
 		for (uint32_t i = 0; i < m_info.images.size(); i++) {
 			auto& image = m_info.images[i];
@@ -1939,6 +1941,9 @@ private:
 			if (sampler == UINT32_MAX) {
 				Fail(flags.pc, "sampler resource limit exceeded");
 			}
+			m_info.samplers[sampler].gather_lod |=
+			    op == ValueOpcode::ImageGatherRaw &&
+			    (memory.image_sample_flags & Decoder::ImageSampleFlagLod) != 0u;
 			AddHandlePatch(sampler_handle, sampler, flags.pc);
 			AddSampledPair(resource, sampler, flags.pc);
 		}