From b4853a0e083cb78c89d7c0bfd098101f51fcc0a9 Mon Sep 17 00:00:00 2001
From: nmzik <Nmzik@mail.ru>
Date: Fri, 9 Oct 2026 02:42:43 +0200
Subject: [PATCH] shader: preserve export vectors instead of rebuilding scalar
 components

---
 .../backend/spirv/spirvEmitterFlow.cpp        | 68 +++++++++----------
 tests/shaderCfgTests.cpp                      |  5 +-
 2 files changed, 35 insertions(+), 38 deletions(-)

diff --git a/src/graphics/shader/recompiler/backend/spirv/spirvEmitterFlow.cpp b/src/graphics/shader/recompiler/backend/spirv/spirvEmitterFlow.cpp
index f53790ea4..33a20fcbd 100644
--- a/src/graphics/shader/recompiler/backend/spirv/spirvEmitterFlow.cpp
+++ b/src/graphics/shader/recompiler/backend/spirv/spirvEmitterFlow.cpp
@@ -304,50 +304,46 @@ uint32_t ExportVector(ValueEmitContext& ctx, uint32_t data, const IR::ExportInfo
 		                          f32[0], f32[1], f32[2], f32[3]);
 		return vector;
 	}
-	uint32_t raw[4] = {
-	    ConstantU32(state, 0),
-	    ConstantU32(state, 0),
-	    ConstantU32(state, 0),
-	    ConstantU32(state, uint_output ? 1u : 0x3f800000u),
-	};
-	if (exp.compr) {
-		for (uint32_t pair = 0; pair < 2u; pair++) {
-			if ((exp.en & (3u << (pair * 2u))) == 0u) {
-				continue;
-			}
-			const auto packed = ExportRawComponent(ctx, data, pair);
-			for (uint32_t lane = 0; lane < 2u; lane++) {
-				const auto component = pair * 2u + lane;
-				if (((exp.en >> component) & 1u) == 0u) {
+	if (exp.compr || exp.en != 0xfu) {
+		uint32_t raw[4] = {
+		    ConstantU32(state, 0),
+		    ConstantU32(state, 0),
+		    ConstantU32(state, 0),
+		    ConstantU32(state, uint_output ? 1u : 0x3f800000u),
+		};
+		if (exp.compr) {
+			for (uint32_t pair = 0; pair < 2u; pair++) {
+				if ((exp.en & (3u << (pair * 2u))) == 0u) {
 					continue;
 				}
-				raw[component] = state.builder.AllocateId();
-				state.builder.AddFunction(spv::OpBitFieldUExtract, TypeU32(state), raw[component],
-				                          packed, ConstantU32(state, lane * 16u),
-				                          ConstantU32(state, 16));
-			}
-		}
-	} else {
-		for (uint32_t component = 0; component < 4u; component++) {
-			if (((exp.en >> component) & 1u) != 0u) {
-				raw[component] = ExportRawComponent(ctx, data, component);
+				const auto packed = ExportRawComponent(ctx, data, pair);
+				for (uint32_t lane = 0; lane < 2u; lane++) {
+					const auto component = pair * 2u + lane;
+					if (((exp.en >> component) & 1u) == 0u) {
+						continue;
+					}
+					raw[component] = state.builder.AllocateId();
+					state.builder.AddFunction(spv::OpBitFieldUExtract, TypeU32(state), raw[component],
+					                          packed, ConstantU32(state, lane * 16u),
+					                          ConstantU32(state, 16));
+				}
+			}
+		} else {
+			for (uint32_t component = 0; component < 4u; component++) {
+				if (((exp.en >> component) & 1u) != 0u) {
+					raw[component] = ExportRawComponent(ctx, data, component);
+				}
 			}
 		}
+		data = state.builder.AllocateId();
+		state.builder.AddFunction(spv::OpCompositeConstruct, TypeU32Vector(state, 4), data,
+		                          raw[0], raw[1], raw[2], raw[3]);
 	}
 	if (uint_output) {
-		const auto vector = state.builder.AllocateId();
-		state.builder.AddFunction(spv::OpCompositeConstruct, TypeU32Vector(state, 4), vector,
-		                          raw[0], raw[1], raw[2], raw[3]);
-		return vector;
-	}
-	uint32_t f32[4] {};
-	for (uint32_t component = 0; component < 4u; component++) {
-		f32[component] = state.builder.AllocateId();
-		state.builder.AddFunction(spv::OpBitcast, TypeF32(state), f32[component], raw[component]);
+		return data;
 	}
 	const auto vector = state.builder.AllocateId();
-	state.builder.AddFunction(spv::OpCompositeConstruct, TypeF32Vector(state, 4), vector, f32[0],
-	                          f32[1], f32[2], f32[3]);
+	state.builder.AddFunction(spv::OpBitcast, TypeF32Vector(state, 4), vector, data);
 	return vector;
 }
 
diff --git a/tests/shaderCfgTests.cpp b/tests/shaderCfgTests.cpp
index e29c76c89..f603117c1 100644
--- a/tests/shaderCfgTests.cpp
+++ b/tests/shaderCfgTests.cpp
@@ -12826,7 +12826,7 @@ void TestNewShaderRecompilerExpPixelOutputs() {
   options.input_info.pixel = &default_info;
   auto partial_result = RecompileForTest(partial_shader, options);
   const auto partial_source = DisassembleSpirvBinary(partial_result.spirv);
-  Check(SpirvSourceHasInstructionOperand(partial_source, "OpBitcast",
+  Check(SpirvSourceHasInstructionOperand(partial_source, "OpCompositeConstruct",
                                          "%uint_1065353216"),
         "disabled float alpha export did not default to 1.0f bits");
   CheckSpirvBinaryValidates(partial_result.spirv);
@@ -13228,8 +13228,9 @@ void TestLogicalAlphaBlendExport() {
   const auto source = DisassembleSpirvBinary(guest.spirv);
   Check(source.find("OpDecorate %out_mrt_1 Location 0") != std::string::npos &&
             source.find("OpDecorate %out_mrt_1 Index 1") != std::string::npos &&
+            CountSourceOccurrences(source, "OpStore %out_mrt_0 ") == 1 &&
             CountSourceOccurrences(source, "OpStore %out_mrt_1 ") == 1 &&
-            SpirvInstructionOpcodeCount(guest.spirv, 81u) == 8u,
+            !SpirvContainsVectorShuffle(guest.spirv, {3u, 3u, 3u, 3u}),
         "guest dual-source export was replaced by synthetic alpha");
 }