[vulkan] Implementation for VK_EXT_shader_quad_control (#4168)

An experimental approach to introduce an smarter way to use and access QUAD's capabilities on shaders, suggested by @gidoly some months ago, finally came into something usable; current implementation checks GLASM, GLSL and Vulkan on their own way, stablishes proper emitters and receivers for Quads inside our recompiler, which are the introductions for future changes; checks for support and actual feature bit, OpCodes and mask were added within this PR. Meanwhile the expected behavior was to reduce graphical issues (on games with Quad shaders reliant), we encountered a very slight performance increase depending on what game and shader are actually compiled.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4168
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Samuel <lizzie@eden-emu.dev>

src/shader_recompiler/backend/glasm/emit_glasm_instructions.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
@@ -665,6 +665,8 @@ void EmitShuffleDown(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, ScalarU3
                      const IR::Value& clamp, const IR::Value& segmentation_mask);
 void EmitShuffleButterfly(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, ScalarU32 index,
                           const IR::Value& clamp, const IR::Value& segmentation_mask);
+void EmitQuadBroadcast(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, ScalarU32 lane);
+void EmitQuadSwap(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, ScalarU32 direction);
 void EmitFSwizzleAdd(EmitContext& ctx, IR::Inst& inst, ScalarF32 op_a, ScalarF32 op_b,
                      ScalarU32 swizzle);
 void EmitDPdxFine(EmitContext& ctx, IR::Inst& inst, ScalarF32 op_a);

src/shader_recompiler/backend/glasm/emit_glasm_warp.cpp

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -97,6 +100,24 @@ void EmitShuffleButterfly(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, Sca
     Shuffle(ctx, inst, value, index, clamp, segmentation_mask, "XOR");
 }
 
+void EmitQuadBroadcast(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, ScalarU32 lane) {
+    const Register ret{ctx.reg_alloc.Define(inst)};
+    ctx.Add("AND.U RC.x,{}.threadid,~3;"
+            "AND.U RC.y,{},3;"
+            "OR.U RC.x,RC.x,RC.y;"
+            "SHFIDX.U {},{},RC.x,0x1C03;"
+            "MOV.U {}.x,{}.y;",
+            ctx.stage_name, lane, ret, value, ret, ret);
+}
+
+void EmitQuadSwap(EmitContext& ctx, IR::Inst& inst, ScalarU32 value, ScalarU32 direction) {
+    const Register ret{ctx.reg_alloc.Define(inst)};
+    ctx.Add("ADD.U RC.x,{},1;"
+            "SHFXOR.U {},{},RC.x,0x1C03;"
+            "MOV.U {}.x,{}.y;",
+            direction, ret, value, ret, ret);
+}
+
 void EmitFSwizzleAdd(EmitContext& ctx, IR::Inst& inst, ScalarF32 op_a, ScalarF32 op_b,
                      ScalarU32 swizzle) {
     const auto ret{ctx.reg_alloc.Define(inst)};

src/shader_recompiler/backend/glsl/emit_glsl_instructions.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
@@ -743,6 +743,10 @@ void EmitShuffleDown(EmitContext& ctx, IR::Inst& inst, std::string_view value,
 void EmitShuffleButterfly(EmitContext& ctx, IR::Inst& inst, std::string_view value,
                           std::string_view index, std::string_view clamp,
                           std::string_view segmentation_mask);
+void EmitQuadBroadcast(EmitContext& ctx, IR::Inst& inst, std::string_view value,
+                       std::string_view lane);
+void EmitQuadSwap(EmitContext& ctx, IR::Inst& inst, std::string_view value,
+                  std::string_view direction);
 void EmitFSwizzleAdd(EmitContext& ctx, IR::Inst& inst, std::string_view op_a, std::string_view op_b,
                      std::string_view swizzle);
 void EmitDPdxFine(EmitContext& ctx, IR::Inst& inst, std::string_view op_a);

src/shader_recompiler/backend/glsl/emit_glsl_warp.cpp

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -200,6 +203,18 @@ void EmitShuffleButterfly(EmitContext& ctx, IR::Inst& inst, std::string_view val
     ctx.AddU32("{}=shfl_in_bounds?shfl_result:{};", inst, value);
 }
 
+void EmitQuadBroadcast(EmitContext& ctx, IR::Inst& inst, std::string_view value,
+                       std::string_view lane) {
+    const auto src_thread_id{fmt::format("(({}&~3)|({}& 3))", THREAD_ID, lane)};
+    ctx.AddU32("{}=readInvocationARB({},{});", inst, value, src_thread_id);
+}
+
+void EmitQuadSwap(EmitContext& ctx, IR::Inst& inst, std::string_view value,
+                  std::string_view direction) {
+    const auto src_thread_id{fmt::format("({}^({}+1))", THREAD_ID, direction)};
+    ctx.AddU32("{}=readInvocationARB({},{});", inst, value, src_thread_id);
+}
+
 void EmitFSwizzleAdd(EmitContext& ctx, IR::Inst& inst, std::string_view op_a, std::string_view op_b,
                      std::string_view swizzle) {
     const auto mask{fmt::format("({}>>((gl_SubGroupInvocationARB&3)<<1))&3", swizzle)};

src/shader_recompiler/backend/spirv/emit_spirv.cpp

@@ -322,6 +322,11 @@ void DefineEntryPoint(const IR::Program& program, EmitContext& ctx, Id main) {
         if (ctx.runtime_info.force_early_z) {
             ctx.AddExecutionMode(main, spv::ExecutionMode::EarlyFragmentTests);
         }
+        if (ctx.profile.support_shader_quad_control && program.info.uses_quad_shuffles) {
+            ctx.AddExtension("SPV_KHR_quad_control");
+            ctx.AddCapability(spv::Capability::QuadControlKHR);
+            ctx.AddExecutionMode(main, spv::ExecutionMode::RequireFullQuadsKHR);
+        }
         break;
     default:
         throw NotImplementedException("Stage {}", program.stage);
@@ -443,6 +448,12 @@ void SetupCapabilities(const Profile& profile, const Info& info, EmitContext& ct
             ctx.AddCapability(spv::Capability::GroupNonUniformVote);
         }
     }
+    if (info.uses_quad_shuffles) {
+        if (profile.support_quad_shuffles) {
+            ctx.AddCapability(spv::Capability::GroupNonUniformQuad);
+        }
+        ctx.AddCapability(spv::Capability::GroupNonUniformShuffle);
+    }
     if (info.uses_int64_bit_atomics && profile.support_int64_atomics) {
         ctx.AddCapability(spv::Capability::Int64Atomics);
     }

src/shader_recompiler/backend/spirv/emit_spirv_instructions.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
@@ -622,6 +622,8 @@ Id EmitShuffleDown(EmitContext& ctx, IR::Inst* inst, Id value, Id index, Id clam
                    Id segmentation_mask);
 Id EmitShuffleButterfly(EmitContext& ctx, IR::Inst* inst, Id value, Id index, Id clamp,
                         Id segmentation_mask);
+Id EmitQuadBroadcast(EmitContext& ctx, Id value, Id lane);
+Id EmitQuadSwap(EmitContext& ctx, Id value, Id direction);
 Id EmitFSwizzleAdd(EmitContext& ctx, Id op_a, Id op_b, Id swizzle);
 Id EmitDPdxFine(EmitContext& ctx, Id op_a);
 Id EmitDPdyFine(EmitContext& ctx, Id op_a);

src/shader_recompiler/backend/spirv/emit_spirv_warp.cpp

@@ -260,6 +260,21 @@ Id EmitShuffleButterfly(EmitContext& ctx, IR::Inst* inst, Id value, Id index, Id
     return SelectValue(ctx, in_range, value, src_thread_id);
 }
 
+Id EmitQuadBroadcast(EmitContext& ctx, Id value, Id lane) {
+    if (ctx.profile.support_quad_shuffles) {
+        return ctx.OpGroupNonUniformQuadBroadcast(ctx.U32[1], SubgroupScope(ctx), value, lane);
+    }
+    const Id base{ctx.OpBitwiseAnd(ctx.U32[1], GetThreadId(ctx), ctx.Const(~3u))};
+    const Id local_lane{ctx.OpBitwiseAnd(ctx.U32[1], lane, ctx.Const(3u))};
+    const Id src_thread_id{ctx.OpBitwiseOr(ctx.U32[1], base, local_lane)};
+    return ctx.OpGroupNonUniformShuffle(ctx.U32[1], SubgroupScope(ctx), value, src_thread_id);
+}
+
+Id EmitQuadSwap(EmitContext& ctx, Id value, Id direction) {
+    const Id xor_mask{ctx.OpIAdd(ctx.U32[1], direction, ctx.Const(1u))};
+    return ctx.OpGroupNonUniformShuffleXor(ctx.U32[1], SubgroupScope(ctx), value, xor_mask);
+}
+
 Id EmitFSwizzleAdd(EmitContext& ctx, Id op_a, Id op_b, Id swizzle) {
     const Id three{ctx.Const(3U)};
     Id mask{GetThreadId(ctx)};

src/shader_recompiler/frontend/ir/ir_emitter.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
@@ -2100,6 +2100,14 @@ U32 IREmitter::ShuffleButterfly(const IR::U32& value, const IR::U32& index, cons
     return Inst<U32>(Opcode::ShuffleButterfly, value, index, clamp, seg_mask);
 }
 
+U32 IREmitter::QuadBroadcast(const IR::U32& value, const IR::U32& lane) {
+    return Inst<U32>(Opcode::QuadBroadcast, value, lane);
+}
+
+U32 IREmitter::QuadSwap(const IR::U32& value, const IR::U32& direction) {
+    return Inst<U32>(Opcode::QuadSwap, value, direction);
+}
+
 F32 IREmitter::FSwizzleAdd(const F32& a, const F32& b, const U32& swizzle, FpControl control) {
     return Inst<F32>(Opcode::FSwizzleAdd, Flags{control}, a, b, swizzle);
 }

src/shader_recompiler/frontend/ir/ir_emitter.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
@@ -394,6 +394,8 @@ public:
                                   const IR::U32& seg_mask);
     [[nodiscard]] U32 ShuffleButterfly(const IR::U32& value, const IR::U32& index,
                                        const IR::U32& clamp, const IR::U32& seg_mask);
+    [[nodiscard]] U32 QuadBroadcast(const IR::U32& value, const IR::U32& lane);
+    [[nodiscard]] U32 QuadSwap(const IR::U32& value, const IR::U32& direction);
     [[nodiscard]] F32 FSwizzleAdd(const F32& a, const F32& b, const U32& swizzle,
                                   FpControl control = {});
 

src/shader_recompiler/frontend/ir/opcodes.cpp

@@ -10,7 +10,7 @@ namespace Shader::IR {
 
 namespace Detail {
 
-OpcodeMeta META_TABLE[532] = {
+OpcodeMeta META_TABLE[534] = {
 #define OPCODE(name_token, type_token, ...)                                                        \
     {                                                                                              \
         .name{#name_token},                                                                        \
@@ -21,7 +21,7 @@ OpcodeMeta META_TABLE[532] = {
 #undef OPCODE
 };
 
-u8 NUM_ARGS[532] = {
+u8 NUM_ARGS[534] = {
 #define OPCODE(name_token, type_token, ...) u8(CalculateNumArgsOf(Opcode::name_token)),
 #include "opcodes.inc"
 #undef OPCODE

src/shader_recompiler/frontend/ir/opcodes.h

@@ -57,12 +57,12 @@ static constexpr Type F64x2{Type::F64x2};
 static constexpr Type F64x3{Type::F64x3};
 static constexpr Type F64x4{Type::F64x4};
 
-extern OpcodeMeta META_TABLE[532];
+extern OpcodeMeta META_TABLE[534];
 constexpr size_t CalculateNumArgsOf(Opcode op) noexcept {
     const auto& arg_types = META_TABLE[size_t(op)].arg_types;
     return size_t(std::distance(arg_types.begin(), std::ranges::find(arg_types, Type::Void)));
 }
-extern u8 NUM_ARGS[532];
+extern u8 NUM_ARGS[534];
 } // namespace Detail
 
 /// Get return type of an opcode

src/shader_recompiler/frontend/ir/opcodes.inc

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -579,6 +582,8 @@ OPCODE(ShuffleIndex,                                        U32,            U32,
 OPCODE(ShuffleUp,                                           U32,            U32,            U32,            U32,            U32,                            )
 OPCODE(ShuffleDown,                                         U32,            U32,            U32,            U32,            U32,                            )
 OPCODE(ShuffleButterfly,                                    U32,            U32,            U32,            U32,            U32,                            )
+OPCODE(QuadBroadcast,                                       U32,            U32,            U32,                                                                    )
+OPCODE(QuadSwap,                                            U32,            U32,            U32,                                                                    )
 OPCODE(FSwizzleAdd,                                         F32,            F32,            F32,            U32,                                            )
 OPCODE(DPdxFine,                                            F32,            F32,                                                                            )
 OPCODE(DPdyFine,                                            F32,            F32,                                                                            )

src/shader_recompiler/frontend/maxwell/translate/impl/warp_shuffle.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
@@ -36,7 +36,10 @@ enum class ShuffleMode : u64 {
     }
 }
 
-void Shuffle(TranslatorVisitor& v, u64 insn, const IR::U32& index, const IR::U32& mask) {
+constexpr u32 QUAD_MASK = (28u << 8) | 3u;
+
+void Shuffle(TranslatorVisitor& v, u64 insn, const IR::U32& index, const IR::U32& mask,
+             bool index_is_imm, u32 index_imm, bool mask_is_imm, u32 mask_imm) {
     union {
         u64 insn;
         BitField<0, 8, IR::Reg> dest_reg;
@@ -45,6 +48,21 @@ void Shuffle(TranslatorVisitor& v, u64 insn, const IR::U32& index, const IR::U32
         BitField<48, 3, IR::Pred> pred;
     } const shfl{insn};
 
+    const bool is_quad_candidate{mask_is_imm && mask_imm == QUAD_MASK && index_is_imm &&
+                                  v.env.ShaderStage() == Stage::Fragment};
+    if (is_quad_candidate) {
+        if (shfl.mode == ShuffleMode::IDX && index_imm <= 3) {
+            v.X(shfl.dest_reg, v.ir.QuadBroadcast(v.X(shfl.src_reg), v.ir.Imm32(index_imm)));
+            v.ir.SetPred(shfl.pred, v.ir.Imm1(true));
+            return;
+        }
+        if (shfl.mode == ShuffleMode::BFLY && index_imm >= 1 && index_imm <= 3) {
+            v.X(shfl.dest_reg, v.ir.QuadSwap(v.X(shfl.src_reg), v.ir.Imm32(index_imm - 1)));
+            v.ir.SetPred(shfl.pred, v.ir.Imm1(true));
+            return;
+        }
+    }
+
     const IR::U32 result{ShuffleOperation(v.ir, v.X(shfl.src_reg), index, mask, shfl.mode)};
     v.ir.SetPred(shfl.pred, v.ir.GetInBoundsFromOp(result));
     v.X(shfl.dest_reg, result);
@@ -59,11 +77,14 @@ void TranslatorVisitor::SHFL(u64 insn) {
         BitField<29, 1, u64> src_b_flag;
         BitField<34, 13, u64> src_b_imm;
     } const flags{insn};
-    const IR::U32 src_a{flags.src_a_flag != 0 ? ir.Imm32(static_cast<u32>(flags.src_a_imm))
-                                              : GetReg20(insn)};
-    const IR::U32 src_b{flags.src_b_flag != 0 ? ir.Imm32(static_cast<u32>(flags.src_b_imm))
-                                              : GetReg39(insn)};
-    Shuffle(*this, insn, src_a, src_b);
+    const bool index_is_imm{flags.src_a_flag != 0};
+    const bool mask_is_imm{flags.src_b_flag != 0};
+    const IR::U32 src_a{index_is_imm ? ir.Imm32(static_cast<u32>(flags.src_a_imm))
+                                     : GetReg20(insn)};
+    const IR::U32 src_b{mask_is_imm ? ir.Imm32(static_cast<u32>(flags.src_b_imm))
+                                    : GetReg39(insn)};
+    Shuffle(*this, insn, src_a, src_b, index_is_imm, static_cast<u32>(flags.src_a_imm),
+            mask_is_imm, static_cast<u32>(flags.src_b_imm));
 }
 
 } // namespace Shader::Maxwell

src/shader_recompiler/ir_opt/collect_shader_info_pass.cpp

@@ -498,6 +498,10 @@ void VisitUsages(Info& info, IR::Inst& inst) {
     case IR::Opcode::ShuffleButterfly:
         info.uses_subgroup_shuffles = true;
         break;
+    case IR::Opcode::QuadBroadcast:
+    case IR::Opcode::QuadSwap:
+        info.uses_quad_shuffles = true;
+        break;
     case IR::Opcode::GetCbufU8:
     case IR::Opcode::GetCbufS8:
     case IR::Opcode::GetCbufU16:

src/shader_recompiler/profile.h

@@ -37,6 +37,8 @@ struct Profile {
     bool support_explicit_workgroup_layout{};
     bool support_workgroup_layout_8bit_access{};
     bool support_workgroup_layout_16bit_access{};
+    bool support_shader_quad_control{};
+    bool support_quad_shuffles{};
     bool support_vote{};
     u32 supported_subgroup_stages{0x7F};
     bool support_viewport_index_layer_non_geometry{};

src/shader_recompiler/shader_info.h

@@ -252,6 +252,7 @@ struct Info {
     bool uses_is_helper_invocation{};
     bool uses_subgroup_invocation_id{};
     bool uses_subgroup_shuffles{};
+    bool uses_quad_shuffles{};
     std::array<bool, 30> uses_patches{};
 
     std::array<Interpolation, 32> interpolation{};

src/video_core/renderer_vulkan/vk_pipeline_cache.cpp

@@ -404,6 +404,8 @@ PipelineCache::PipelineCache(Tegra::MaxwellDeviceMemoryManager& device_memory_,
             device.IsWorkgroupMemoryExplicitLayout8BitAccessSupported(),
         .support_workgroup_layout_16bit_access =
             device.IsWorkgroupMemoryExplicitLayout16BitAccessSupported(),
+        .support_shader_quad_control = device.IsKhrShaderQuadControlSupported(),
+        .support_quad_shuffles = device.IsSubgroupFeatureSupported(VK_SUBGROUP_FEATURE_QUAD_BIT),
         .support_vote = device.IsSubgroupFeatureSupported(VK_SUBGROUP_FEATURE_VOTE_BIT),
         .supported_subgroup_stages = supported_subgroup_stages,
         .support_viewport_index_layer_non_geometry =

src/video_core/vulkan_common/vulkan_device.cpp

@@ -1386,6 +1386,11 @@ void Device::RemoveUnsuitableExtensions() {
                                VK_KHR_PIPELINE_EXECUTABLE_PROPERTIES_EXTENSION_NAME);
     }
 
+    // VK_KHR_shader_quad_control
+    extensions.shader_quad_control = features.shader_quad_control.shaderQuadControl;
+    RemoveExtensionFeatureIfUnsuitable(extensions.shader_quad_control, features.shader_quad_control,
+                                       VK_KHR_SHADER_QUAD_CONTROL_EXTENSION_NAME);
+
     // VK_KHR_workgroup_memory_explicit_layout
     extensions.workgroup_memory_explicit_layout =
         features.workgroup_memory_explicit_layout.workgroupMemoryExplicitLayout &&

src/video_core/vulkan_common/vulkan_device.h

@@ -75,6 +75,7 @@ VK_DEFINE_HANDLE(VmaAllocator)
     FEATURE(KHR, Maintenance6, MAINTENANCE_6, maintenance6)                                        \
     FEATURE(KHR, PipelineExecutableProperties, PIPELINE_EXECUTABLE_PROPERTIES,                     \
             pipeline_executable_properties)                                                        \
+    FEATURE(KHR, ShaderQuadControl, SHADER_QUAD_CONTROL, shader_quad_control)                      \
     FEATURE(KHR, WorkgroupMemoryExplicitLayout, WORKGROUP_MEMORY_EXPLICIT_LAYOUT,                  \
             workgroup_memory_explicit_layout)
 
@@ -586,6 +587,11 @@ FN_MAX_LIMIT_LIST
                features.features.shaderInt16;
     }
 
+    /// Returns true if the device supports VK_KHR_shader_quad_control.
+    bool IsKhrShaderQuadControlSupported() const {
+        return extensions.shader_quad_control && features.shader_quad_control.shaderQuadControl;
+    }
+
     /// Returns true if the device supports VK_KHR_image_format_list.
     bool IsKhrImageFormatListSupported() const {
         return extensions.image_format_list || instance_version >= VK_API_VERSION_1_2;