glasm: Rework control flow introducing a syntax list

This commit regresses VertexA shaders, their transformation pass has to
be adapted to the new control flow.

src/shader_recompiler/CMakeLists.txt

@@ -51,6 +51,7 @@ add_library(shader_recompiler STATIC
     backend/spirv/emit_spirv_warp.cpp
     environment.h
     exception.h
+    frontend/ir/abstract_syntax_list.h
     frontend/ir/attribute.cpp
     frontend/ir/attribute.h
     frontend/ir/basic_block.cpp

src/shader_recompiler/backend/glasm/emit_glasm.cpp

@@ -117,8 +117,6 @@ auto Arg(EmitContext& ctx, const IR::Value& arg) {
         return Identity<const IR::Value&>{arg};
     } else if constexpr (std::is_same_v<ArgType, u32>) {
         return Identity{arg.U32()};
-    } else if constexpr (std::is_same_v<ArgType, IR::Block*>) {
-        return Identity{arg.Label()};
     } else if constexpr (std::is_same_v<ArgType, IR::Attribute>) {
         return Identity{arg.Attribute()};
     } else if constexpr (std::is_same_v<ArgType, IR::Patch>) {
@@ -177,6 +175,39 @@ void EmitInst(EmitContext& ctx, IR::Inst* inst) {
     throw LogicError("Invalid opcode {}", inst->GetOpcode());
 }
 
+void EmitCode(EmitContext& ctx, const IR::Program& program) {
+    const auto eval{
+        [&](const IR::U1& cond) { return ScalarS32{ctx.reg_alloc.Consume(IR::Value{cond})}; }};
+    for (const IR::AbstractSyntaxNode& node : program.syntax_list) {
+        switch (node.type) {
+        case IR::AbstractSyntaxNode::Type::Block:
+            for (IR::Inst& inst : node.block->Instructions()) {
+                EmitInst(ctx, &inst);
+            }
+            break;
+        case IR::AbstractSyntaxNode::Type::If:
+            ctx.Add("MOV.S.CC RC,{};IF NE.x;", eval(node.if_node.cond));
+            break;
+        case IR::AbstractSyntaxNode::Type::EndIf:
+            ctx.Add("ENDIF;");
+            break;
+        case IR::AbstractSyntaxNode::Type::Loop:
+            ctx.Add("REP;");
+            break;
+        case IR::AbstractSyntaxNode::Type::Repeat:
+            ctx.Add("MOV.S.CC RC,{};BRK NE.x;ENDREP;", eval(node.repeat.cond));
+            break;
+        case IR::AbstractSyntaxNode::Type::Break:
+            ctx.Add("MOV.S.CC RC,{};BRK NE.x;", eval(node.repeat.cond));
+            break;
+        case IR::AbstractSyntaxNode::Type::Return:
+        case IR::AbstractSyntaxNode::Type::Unreachable:
+            ctx.Add("RET;");
+            break;
+        }
+    }
+}
+
 void SetupOptions(std::string& header, Info info) {
     if (info.uses_int64_bit_atomics) {
         header += "OPTION NV_shader_atomic_int64;";
@@ -201,11 +232,7 @@ void SetupOptions(std::string& header, Info info) {
 
 std::string EmitGLASM(const Profile&, IR::Program& program, Bindings&) {
     EmitContext ctx{program};
-    for (IR::Block* const block : program.blocks) {
-        for (IR::Inst& inst : block->Instructions()) {
-            EmitInst(ctx, &inst);
-        }
-    }
+    EmitCode(ctx, program);
     std::string header = "!!NVcp5.0\n"
                          "OPTION NV_internal;";
     SetupOptions(header, program.info);

src/shader_recompiler/backend/glasm/emit_glasm_instructions.h

@@ -22,13 +22,8 @@ class EmitContext;
 void EmitPhi(EmitContext& ctx, IR::Inst& inst);
 void EmitVoid(EmitContext& ctx);
 void EmitIdentity(EmitContext& ctx, IR::Inst& inst, const IR::Value& value);
-void EmitBranch(EmitContext& ctx);
-void EmitBranchConditional(EmitContext& ctx);
-void EmitLoopMerge(EmitContext& ctx);
-void EmitSelectionMerge(EmitContext& ctx);
-void EmitReturn(EmitContext& ctx);
+void EmitBranchConditionRef(EmitContext&);
 void EmitJoin(EmitContext& ctx);
-void EmitUnreachable(EmitContext& ctx);
 void EmitDemoteToHelperInvocation(EmitContext& ctx);
 void EmitBarrier(EmitContext& ctx);
 void EmitWorkgroupMemoryBarrier(EmitContext& ctx);

src/shader_recompiler/backend/glasm/emit_glasm_integer.cpp

@@ -91,7 +91,8 @@ void EmitBitFieldInsert(EmitContext& ctx, IR::Inst& inst, ScalarS32 base, Scalar
     if (count.type != Type::Register && offset.type != Type::Register) {
         ctx.Add("BFI.S {},{{{},{},0,0}},{},{};", ret, count, offset, insert, base);
     } else {
-        ctx.Add("MOV.S RC.x,{};MOV.U RC.y,{};"
+        ctx.Add("MOV.S RC.x,{};"
+                "MOV.S RC.y,{};"
                 "BFI.S {},RC,{},{};",
                 count, offset, ret, insert, base);
     }
@@ -103,7 +104,8 @@ void EmitBitFieldSExtract(EmitContext& ctx, IR::Inst& inst, ScalarS32 base, Scal
     if (count.type != Type::Register && offset.type != Type::Register) {
         ctx.Add("BFE.S {},{{{},{},0,0}},{};", ret, count, offset, base);
     } else {
-        ctx.Add("MOV.S RC.x,{};MOV.U RC.y,{};"
+        ctx.Add("MOV.S RC.x,{};"
+                "MOV.S RC.y,{};"
                 "BFE.S {},RC,{};",
                 count, offset, ret, base);
     }
@@ -115,7 +117,8 @@ void EmitBitFieldUExtract(EmitContext& ctx, IR::Inst& inst, ScalarU32 base, Scal
     if (count.type != Type::Register && offset.type != Type::Register) {
         ctx.Add("BFE.U {},{{{},{},0,0}},{};", ret, count, offset, base);
     } else {
-        ctx.Add("MOV.U RC.x,{};MOV.U RC.y,{};"
+        ctx.Add("MOV.U RC.x,{};"
+                "MOV.U RC.y,{};"
                 "BFE.U {},RC,{};",
                 count, offset, ret, base);
     }

src/shader_recompiler/backend/glasm/emit_glasm_not_implemented.cpp

@@ -23,34 +23,12 @@ void EmitPhi(EmitContext& ctx, IR::Inst& inst) {
 
 void EmitVoid(EmitContext&) {}
 
-void EmitBranch(EmitContext& ctx) {
-    NotImplemented();
-}
-
-void EmitBranchConditional(EmitContext& ctx) {
-    NotImplemented();
-}
-
-void EmitLoopMerge(EmitContext& ctx) {
-    NotImplemented();
-}
-
-void EmitSelectionMerge(EmitContext& ctx) {
-    NotImplemented();
-}
-
-void EmitReturn(EmitContext& ctx) {
-    ctx.Add("RET;");
-}
+void EmitBranchConditionRef(EmitContext&) {}
 
 void EmitJoin(EmitContext& ctx) {
     NotImplemented();
 }
 
-void EmitUnreachable(EmitContext& ctx) {
-    NotImplemented();
-}
-
 void EmitDemoteToHelperInvocation(EmitContext& ctx) {
     NotImplemented();
 }

src/shader_recompiler/backend/spirv/emit_context.cpp

@@ -463,7 +463,6 @@ EmitContext::EmitContext(const Profile& profile_, IR::Program& program, Bindings
     DefineImages(program.info, image_binding);
     DefineAttributeMemAccess(program.info);
     DefineGlobalMemoryFunctions(program.info);
-    DefineLabels(program);
 }
 
 EmitContext::~EmitContext() = default;
@@ -487,8 +486,6 @@ Id EmitContext::Def(const IR::Value& value) {
         return Const(value.F32());
     case IR::Type::F64:
         return Constant(F64[1], value.F64());
-    case IR::Type::Label:
-        return value.Label()->Definition<Id>();
     default:
         throw NotImplementedException("Immediate type {}", value.Type());
     }
@@ -1139,12 +1136,6 @@ void EmitContext::DefineImages(const Info& info, u32& binding) {
     }
 }
 
-void EmitContext::DefineLabels(IR::Program& program) {
-    for (IR::Block* const block : program.blocks) {
-        block->SetDefinition(OpLabel());
-    }
-}
-
 void EmitContext::DefineInputs(const Info& info) {
     if (info.uses_workgroup_id) {
         workgroup_id = DefineInput(*this, U32[3], false, spv::BuiltIn::WorkgroupId);

src/shader_recompiler/backend/spirv/emit_context.h

@@ -296,7 +296,6 @@ private:
     void DefineImages(const Info& info, u32& binding);
     void DefineAttributeMemAccess(const Info& info);
     void DefineGlobalMemoryFunctions(const Info& info);
-    void DefineLabels(IR::Program& program);
 
     void DefineInputs(const Info& info);
     void DefineOutputs(const IR::Program& program);

src/shader_recompiler/backend/spirv/emit_spirv.cpp

@@ -41,8 +41,6 @@ ArgType Arg(EmitContext& ctx, const IR::Value& arg) {
         return arg;
     } else if constexpr (std::is_same_v<ArgType, u32>) {
         return arg.U32();
-    } else if constexpr (std::is_same_v<ArgType, IR::Block*>) {
-        return arg.Label();
     } else if constexpr (std::is_same_v<ArgType, IR::Attribute>) {
         return arg.Attribute();
     } else if constexpr (std::is_same_v<ArgType, IR::Patch>) {
@@ -109,15 +107,74 @@ Id TypeId(const EmitContext& ctx, IR::Type type) {
     }
 }
 
+void Traverse(EmitContext& ctx, IR::Program& program) {
+    IR::Block* current_block{};
+    for (const IR::AbstractSyntaxNode& node : program.syntax_list) {
+        switch (node.type) {
+        case IR::AbstractSyntaxNode::Type::Block:
+            const Id label{node.block->Definition<Id>()};
+            if (current_block) {
+                ctx.OpBranch(label);
+            }
+            current_block = node.block;
+            ctx.AddLabel(label);
+            for (IR::Inst& inst : node.block->Instructions()) {
+                EmitInst(ctx, &inst);
+            }
+            break;
+        case IR::AbstractSyntaxNode::Type::If: {
+            const Id if_label{node.if_node.body->Definition<Id>()};
+            const Id endif_label{node.if_node.merge->Definition<Id>()};
+            ctx.OpSelectionMerge(endif_label, spv::SelectionControlMask::MaskNone);
+            ctx.OpBranchConditional(ctx.Def(node.if_node.cond), if_label, endif_label);
+            break;
+        }
+        case IR::AbstractSyntaxNode::Type::Loop: {
+            const Id body_label{node.loop.body->Definition<Id>()};
+            const Id continue_label{node.loop.continue_block->Definition<Id>()};
+            const Id endloop_label{node.loop.merge->Definition<Id>()};
+
+            ctx.OpLoopMerge(endloop_label, continue_label, spv::LoopControlMask::MaskNone);
+            ctx.OpBranch(node.loop.body->Definition<Id>());
+            break;
+        }
+        case IR::AbstractSyntaxNode::Type::Break: {
+            const Id break_label{node.break_node.merge->Definition<Id>()};
+            const Id skip_label{node.break_node.skip->Definition<Id>()};
+            ctx.OpBranchConditional(ctx.Def(node.break_node.cond), break_label, skip_label);
+            break;
+        }
+        case IR::AbstractSyntaxNode::Type::EndIf:
+            if (current_block) {
+                ctx.OpBranch(node.end_if.merge->Definition<Id>());
+            }
+            break;
+        case IR::AbstractSyntaxNode::Type::Repeat: {
+            const Id loop_header_label{node.repeat.loop_header->Definition<Id>()};
+            const Id merge_label{node.repeat.merge->Definition<Id>()};
+            ctx.OpBranchConditional(ctx.Def(node.repeat.cond), loop_header_label, merge_label);
+            break;
+        }
+        case IR::AbstractSyntaxNode::Type::Return:
+            ctx.OpReturn();
+            break;
+        case IR::AbstractSyntaxNode::Type::Unreachable:
+            ctx.OpUnreachable();
+            break;
+        }
+        if (node.type != IR::AbstractSyntaxNode::Type::Block) {
+            current_block = nullptr;
+        }
+    }
+}
+
 Id DefineMain(EmitContext& ctx, IR::Program& program) {
     const Id void_function{ctx.TypeFunction(ctx.void_id)};
     const Id main{ctx.OpFunction(ctx.void_id, spv::FunctionControlMask::MaskNone, void_function)};
     for (IR::Block* const block : program.blocks) {
-        ctx.AddLabel(block->Definition<Id>());
-        for (IR::Inst& inst : block->Instructions()) {
-            EmitInst(ctx, &inst);
-        }
+        block->SetDefinition(ctx.OpLabel());
     }
+    Traverse(ctx, program);
     ctx.OpFunctionEnd();
     return main;
 }
@@ -411,6 +468,8 @@ Id EmitIdentity(EmitContext& ctx, const IR::Value& value) {
     return id;
 }
 
+void EmitBranchConditionRef(EmitContext&) {}
+
 void EmitGetZeroFromOp(EmitContext&) {
     throw LogicError("Unreachable instruction");
 }

src/shader_recompiler/backend/spirv/emit_spirv_control_flow.cpp

@@ -7,40 +7,21 @@
 
 namespace Shader::Backend::SPIRV {
 
-void EmitBranch(EmitContext& ctx, Id label) {
-    ctx.OpBranch(label);
-}
-
-void EmitBranchConditional(EmitContext& ctx, Id condition, Id true_label, Id false_label) {
-    ctx.OpBranchConditional(condition, true_label, false_label);
-}
-
-void EmitLoopMerge(EmitContext& ctx, Id merge_label, Id continue_label) {
-    ctx.OpLoopMerge(merge_label, continue_label, spv::LoopControlMask::MaskNone);
-}
-
-void EmitSelectionMerge(EmitContext& ctx, Id merge_label) {
-    ctx.OpSelectionMerge(merge_label, spv::SelectionControlMask::MaskNone);
-}
-
-void EmitReturn(EmitContext& ctx) {
-    ctx.OpReturn();
-}
-
 void EmitJoin(EmitContext&) {
     throw NotImplementedException("Join shouldn't be emitted");
 }
 
-void EmitUnreachable(EmitContext& ctx) {
-    ctx.OpUnreachable();
-}
-
-void EmitDemoteToHelperInvocation(EmitContext& ctx, Id continue_label) {
+void EmitDemoteToHelperInvocation(EmitContext& ctx) {
     if (ctx.profile.support_demote_to_helper_invocation) {
         ctx.OpDemoteToHelperInvocationEXT();
-        ctx.OpBranch(continue_label);
     } else {
+        const Id kill_label{ctx.OpLabel()};
+        const Id impossible_label{ctx.OpLabel()};
+        ctx.OpSelectionMerge(impossible_label, spv::SelectionControlMask::MaskNone);
+        ctx.OpBranchConditional(ctx.true_value, kill_label, impossible_label);
+        ctx.AddLabel(kill_label);
         ctx.OpKill();
+        ctx.AddLabel(impossible_label);
     }
 }
 

src/shader_recompiler/backend/spirv/emit_spirv_instructions.h

@@ -23,14 +23,9 @@ class EmitContext;
 Id EmitPhi(EmitContext& ctx, IR::Inst* inst);
 void EmitVoid(EmitContext& ctx);
 Id EmitIdentity(EmitContext& ctx, const IR::Value& value);
-void EmitBranch(EmitContext& ctx, Id label);
-void EmitBranchConditional(EmitContext& ctx, Id condition, Id true_label, Id false_label);
-void EmitLoopMerge(EmitContext& ctx, Id merge_label, Id continue_label);
-void EmitSelectionMerge(EmitContext& ctx, Id merge_label);
-void EmitReturn(EmitContext& ctx);
+void EmitBranchConditionRef(EmitContext&);
 void EmitJoin(EmitContext& ctx);
-void EmitUnreachable(EmitContext& ctx);
-void EmitDemoteToHelperInvocation(EmitContext& ctx, Id continue_label);
+void EmitDemoteToHelperInvocation(EmitContext& ctx);
 void EmitBarrier(EmitContext& ctx);
 void EmitWorkgroupMemoryBarrier(EmitContext& ctx);
 void EmitDeviceMemoryBarrier(EmitContext& ctx);

src/shader_recompiler/frontend/ir/abstract_syntax_list.h

@@ -0,0 +1,56 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vector>
+
+#include "shader_recompiler/frontend/ir/value.h"
+
+namespace Shader::IR {
+
+class Block;
+
+struct AbstractSyntaxNode {
+    enum class Type {
+        Block,
+        If,
+        EndIf,
+        Loop,
+        Repeat,
+        Break,
+        Return,
+        Unreachable,
+    };
+    Type type{};
+    union {
+        Block* block{};
+        struct {
+            U1 cond;
+            Block* body;
+            Block* merge;
+        } if_node;
+        struct {
+            Block* merge;
+        } end_if;
+        struct {
+            Block* body;
+            Block* continue_block;
+            Block* merge;
+        } loop;
+        struct {
+            U1 cond;
+            Block* loop_header;
+            Block* merge;
+        } repeat;
+        struct {
+            U1 cond;
+            Block* merge;
+            Block* skip;
+        } break_node;
+    };
+};
+using AbstractSyntaxList = std::vector<AbstractSyntaxNode>;
+
+} // namespace Shader::IR

src/shader_recompiler/frontend/ir/basic_block.cpp

@@ -14,10 +14,7 @@
 
 namespace Shader::IR {
 
-Block::Block(ObjectPool<Inst>& inst_pool_, u32 begin, u32 end)
-    : inst_pool{&inst_pool_}, location_begin{begin}, location_end{end} {}
-
-Block::Block(ObjectPool<Inst>& inst_pool_) : Block{inst_pool_, 0, 0} {}
+Block::Block(ObjectPool<Inst>& inst_pool_) : inst_pool{&inst_pool_} {}
 
 Block::~Block() = default;
 
@@ -40,39 +37,15 @@ Block::iterator Block::PrependNewInst(iterator insertion_point, Opcode op,
     return result_it;
 }
 
-void Block::SetBranches(Condition cond, Block* branch_true_, Block* branch_false_) {
-    branch_cond = cond;
-    branch_true = branch_true_;
-    branch_false = branch_false_;
-}
-
-void Block::SetBranch(Block* branch) {
-    branch_cond = Condition{true};
-    branch_true = branch;
-}
-
-void Block::SetReturn() {
-    branch_cond = Condition{true};
-    branch_true = nullptr;
-    branch_false = nullptr;
-}
-
-bool Block::IsVirtual() const noexcept {
-    return location_begin == location_end;
-}
-
-u32 Block::LocationBegin() const noexcept {
-    return location_begin;
-}
-
-u32 Block::LocationEnd() const noexcept {
-    return location_end;
-}
-
-void Block::AddImmediatePredecessor(Block* block) {
-    if (std::ranges::find(imm_predecessors, block) == imm_predecessors.end()) {
-        imm_predecessors.push_back(block);
+void Block::AddBranch(Block* block) {
+    if (std::ranges::find(imm_successors, block) != imm_successors.end()) {
+        throw LogicError("Successor already inserted");
+    }
+    if (std::ranges::find(block->imm_predecessors, this) != block->imm_predecessors.end()) {
+        throw LogicError("Predecessor already inserted");
     }
+    imm_successors.push_back(block);
+    block->imm_predecessors.push_back(this);
 }
 
 static std::string BlockToIndex(const std::map<const Block*, size_t>& block_to_index,
@@ -92,15 +65,11 @@ static size_t InstIndex(std::map<const Inst*, size_t>& inst_to_index, size_t& in
     return it->second;
 }
 
-static std::string ArgToIndex(const std::map<const Block*, size_t>& block_to_index,
-                              std::map<const Inst*, size_t>& inst_to_index, size_t& inst_index,
+static std::string ArgToIndex(std::map<const Inst*, size_t>& inst_to_index, size_t& inst_index,
                               const Value& arg) {
     if (arg.IsEmpty()) {
         return "<null>";
     }
-    if (arg.IsLabel()) {
-        return BlockToIndex(block_to_index, arg.Label());
-    }
     if (!arg.IsImmediate() || arg.IsIdentity()) {
         return fmt::format("%{}", InstIndex(inst_to_index, inst_index, arg.Inst()));
     }
@@ -140,8 +109,7 @@ std::string DumpBlock(const Block& block, const std::map<const Block*, size_t>&
     if (const auto it{block_to_index.find(&block)}; it != block_to_index.end()) {
         ret += fmt::format(" ${}", it->second);
     }
-    ret += fmt::format(": begin={:04x} end={:04x}\n", block.LocationBegin(), block.LocationEnd());
-
+    ret += '\n';
     for (const Inst& inst : block) {
         const Opcode op{inst.GetOpcode()};
         ret += fmt::format("[{:016x}] ", reinterpret_cast<u64>(&inst));
@@ -153,7 +121,7 @@ std::string DumpBlock(const Block& block, const std::map<const Block*, size_t>&
         const size_t arg_count{inst.NumArgs()};
         for (size_t arg_index = 0; arg_index < arg_count; ++arg_index) {
             const Value arg{inst.Arg(arg_index)};
-            const std::string arg_str{ArgToIndex(block_to_index, inst_to_index, inst_index, arg)};
+            const std::string arg_str{ArgToIndex(inst_to_index, inst_index, arg)};
             ret += arg_index != 0 ? ", " : " ";
             if (op == Opcode::Phi) {
                 ret += fmt::format("[ {}, {} ]", arg_str,

src/shader_recompiler/frontend/ir/basic_block.h

@@ -12,6 +12,7 @@
 #include <boost/intrusive/list.hpp>
 
 #include "common/bit_cast.h"
+#include "common/common_types.h"
 #include "shader_recompiler/frontend/ir/condition.h"
 #include "shader_recompiler/frontend/ir/value.h"
 #include "shader_recompiler/object_pool.h"
@@ -27,7 +28,6 @@ public:
     using reverse_iterator = InstructionList::reverse_iterator;
     using const_reverse_iterator = InstructionList::const_reverse_iterator;
 
-    explicit Block(ObjectPool<Inst>& inst_pool_, u32 begin, u32 end);
     explicit Block(ObjectPool<Inst>& inst_pool_);
     ~Block();
 
@@ -44,22 +44,8 @@ public:
     iterator PrependNewInst(iterator insertion_point, Opcode op,
                             std::initializer_list<Value> args = {}, u32 flags = 0);
 
-    /// Set the branches to jump to when all instructions have executed.
-    void SetBranches(Condition cond, Block* branch_true, Block* branch_false);
-    /// Set the branch to unconditionally jump to when all instructions have executed.
-    void SetBranch(Block* branch);
-    /// Mark the block as a return block.
-    void SetReturn();
-
-    /// Returns true when the block does not implement any guest instructions directly.
-    [[nodiscard]] bool IsVirtual() const noexcept;
-    /// Gets the starting location of this basic block.
-    [[nodiscard]] u32 LocationBegin() const noexcept;
-    /// Gets the end location for this basic block.
-    [[nodiscard]] u32 LocationEnd() const noexcept;
-
-    /// Adds a new immediate predecessor to this basic block.
-    void AddImmediatePredecessor(Block* block);
+    /// Adds a new branch to this basic block.
+    void AddBranch(Block* block);
 
     /// Gets a mutable reference to the instruction list for this basic block.
     [[nodiscard]] InstructionList& Instructions() noexcept {
@@ -71,9 +57,13 @@ public:
     }
 
     /// Gets an immutable span to the immediate predecessors.
-    [[nodiscard]] std::span<Block* const> ImmediatePredecessors() const noexcept {
+    [[nodiscard]] std::span<Block* const> ImmPredecessors() const noexcept {
         return imm_predecessors;
     }
+    /// Gets an immutable span to the immediate successors.
+    [[nodiscard]] std::span<Block* const> ImmSuccessors() const noexcept {
+        return imm_successors;
+    }
 
     /// Intrusively store the host definition of this instruction.
     template <typename DefinitionType>
@@ -87,19 +77,6 @@ public:
         return Common::BitCast<DefinitionType>(definition);
     }
 
-    [[nodiscard]] Condition BranchCondition() const noexcept {
-        return branch_cond;
-    }
-    [[nodiscard]] bool IsTerminationBlock() const noexcept {
-        return !branch_true && !branch_false;
-    }
-    [[nodiscard]] Block* TrueBranch() const noexcept {
-        return branch_true;
-    }
-    [[nodiscard]] Block* FalseBranch() const noexcept {
-        return branch_false;
-    }
-
     void SetSsaRegValue(IR::Reg reg, const Value& value) noexcept {
         ssa_reg_values[RegIndex(reg)] = value;
     }
@@ -178,22 +155,14 @@ public:
 private:
     /// Memory pool for instruction list
     ObjectPool<Inst>* inst_pool;
-    /// Starting location of this block
-    u32 location_begin;
-    /// End location of this block
-    u32 location_end;
 
     /// List of instructions in this block
     InstructionList instructions;
 
-    /// Condition to choose the branch to take
-    Condition branch_cond{true};
-    /// Block to jump into when the branch condition evaluates as true
-    Block* branch_true{nullptr};
-    /// Block to jump into when the branch condition evaluates as false
-    Block* branch_false{nullptr};
     /// Block immediate predecessors
     std::vector<Block*> imm_predecessors;
+    /// Block immediate successors
+    std::vector<Block*> imm_successors;
 
     /// Intrusively store the value of a register in the block.
     std::array<Value, NUM_REGS> ssa_reg_values;

src/shader_recompiler/frontend/ir/ir_emitter.cpp

@@ -61,25 +61,28 @@ F64 IREmitter::Imm64(f64 value) const {
     return F64{Value{value}};
 }
 
-void IREmitter::Branch(Block* label) {
-    label->AddImmediatePredecessor(block);
-    block->SetBranch(label);
-    Inst(Opcode::Branch, label);
+void IREmitter::Prologue() {
+    Inst(Opcode::Prologue);
 }
 
-void IREmitter::BranchConditional(const U1& condition, Block* true_label, Block* false_label) {
-    block->SetBranches(IR::Condition{true}, true_label, false_label);
-    true_label->AddImmediatePredecessor(block);
-    false_label->AddImmediatePredecessor(block);
-    Inst(Opcode::BranchConditional, condition, true_label, false_label);
+void IREmitter::Epilogue() {
+    Inst(Opcode::Epilogue);
 }
 
-void IREmitter::LoopMerge(Block* merge_block, Block* continue_target) {
-    Inst(Opcode::LoopMerge, merge_block, continue_target);
+void IREmitter::BranchConditionRef(const U1& cond) {
+    Inst(Opcode::BranchConditionRef, cond);
 }
 
-void IREmitter::SelectionMerge(Block* merge_block) {
-    Inst(Opcode::SelectionMerge, merge_block);
+void IREmitter::DemoteToHelperInvocation() {
+    Inst(Opcode::DemoteToHelperInvocation);
+}
+
+void IREmitter::EmitVertex(const U32& stream) {
+    Inst(Opcode::EmitVertex, stream);
+}
+
+void IREmitter::EndPrimitive(const U32& stream) {
+    Inst(Opcode::EndPrimitive, stream);
 }
 
 void IREmitter::Barrier() {
@@ -94,37 +97,6 @@ void IREmitter::DeviceMemoryBarrier() {
     Inst(Opcode::DeviceMemoryBarrier);
 }
 
-void IREmitter::Return() {
-    block->SetReturn();
-    Inst(Opcode::Return);
-}
-
-void IREmitter::Unreachable() {
-    Inst(Opcode::Unreachable);
-}
-
-void IREmitter::DemoteToHelperInvocation(Block* continue_label) {
-    block->SetBranch(continue_label);
-    continue_label->AddImmediatePredecessor(block);
-    Inst(Opcode::DemoteToHelperInvocation, continue_label);
-}
-
-void IREmitter::Prologue() {
-    Inst(Opcode::Prologue);
-}
-
-void IREmitter::Epilogue() {
-    Inst(Opcode::Epilogue);
-}
-
-void IREmitter::EmitVertex(const U32& stream) {
-    Inst(Opcode::EmitVertex, stream);
-}
-
-void IREmitter::EndPrimitive(const U32& stream) {
-    Inst(Opcode::EndPrimitive, stream);
-}
-
 U32 IREmitter::GetReg(IR::Reg reg) {
     return Inst<U32>(Opcode::GetRegister, reg);
 }

src/shader_recompiler/frontend/ir/ir_emitter.h

@@ -32,17 +32,10 @@ public:
     [[nodiscard]] U64 Imm64(s64 value) const;
     [[nodiscard]] F64 Imm64(f64 value) const;
 
-    void Branch(Block* label);
-    void BranchConditional(const U1& condition, Block* true_label, Block* false_label);
-    void LoopMerge(Block* merge_block, Block* continue_target);
-    void SelectionMerge(Block* merge_block);
-    void Return();
-    void Unreachable();
-    void DemoteToHelperInvocation(Block* continue_label);
-
     void Prologue();
     void Epilogue();
-
+    void BranchConditionRef(const U1& cond);
+    void DemoteToHelperInvocation();
     void EmitVertex(const U32& stream);
     void EndPrimitive(const U32& stream);
 

src/shader_recompiler/frontend/ir/microinstruction.cpp

@@ -56,19 +56,14 @@ Inst::~Inst() {
 
 bool Inst::MayHaveSideEffects() const noexcept {
     switch (op) {
-    case Opcode::Branch:
-    case Opcode::BranchConditional:
-    case Opcode::LoopMerge:
-    case Opcode::SelectionMerge:
-    case Opcode::Return:
+    case Opcode::Prologue:
+    case Opcode::Epilogue:
+    case Opcode::BranchConditionRef:
     case Opcode::Join:
-    case Opcode::Unreachable:
     case Opcode::DemoteToHelperInvocation:
     case Opcode::Barrier:
     case Opcode::WorkgroupMemoryBarrier:
     case Opcode::DeviceMemoryBarrier:
-    case Opcode::Prologue:
-    case Opcode::Epilogue:
     case Opcode::EmitVertex:
     case Opcode::EndPrimitive:
     case Opcode::SetAttribute:

src/shader_recompiler/frontend/ir/opcodes.h

@@ -30,7 +30,6 @@ struct OpcodeMeta {
 // using enum Type;
 constexpr Type Void{Type::Void};
 constexpr Type Opaque{Type::Opaque};
-constexpr Type Label{Type::Label};
 constexpr Type Reg{Type::Reg};
 constexpr Type Pred{Type::Pred};
 constexpr Type Attribute{Type::Attribute};

src/shader_recompiler/frontend/ir/opcodes.inc

@@ -7,27 +7,20 @@ OPCODE(Phi,                                                 Opaque,
 OPCODE(Identity,                                            Opaque,         Opaque,                                                                         )
 OPCODE(Void,                                                Void,                                                                                           )
 
-// Control flow
-OPCODE(Branch,                                              Void,           Label,                                                                          )
-OPCODE(BranchConditional,                                   Void,           U1,             Label,          Label,                                          )
-OPCODE(LoopMerge,                                           Void,           Label,          Label,                                                          )
-OPCODE(SelectionMerge,                                      Void,           Label,                                                                          )
-OPCODE(Return,                                              Void,                                                                                           )
+// Special operations
+OPCODE(Prologue,                                            Void,                                                                                           )
+OPCODE(Epilogue,                                            Void,                                                                                           )
+OPCODE(BranchConditionRef,                                  Void,           U1,                                                                             )
 OPCODE(Join,                                                Void,                                                                                           )
-OPCODE(Unreachable,                                         Void,                                                                                           )
-OPCODE(DemoteToHelperInvocation,                            Void,           Label,                                                                          )
+OPCODE(DemoteToHelperInvocation,                            Void,                                                                                           )
+OPCODE(EmitVertex,                                          Void,           U32,                                                                            )
+OPCODE(EndPrimitive,                                        Void,           U32,                                                                            )
 
 // Barriers
 OPCODE(Barrier,                                             Void,                                                                                           )
 OPCODE(WorkgroupMemoryBarrier,                              Void,                                                                                           )
 OPCODE(DeviceMemoryBarrier,                                 Void,                                                                                           )
 
-// Special operations
-OPCODE(Prologue,                                            Void,                                                                                           )
-OPCODE(Epilogue,                                            Void,                                                                                           )
-OPCODE(EmitVertex,                                          Void,           U32,                                                                            )
-OPCODE(EndPrimitive,                                        Void,           U32,                                                                            )
-
 // Context getters/setters
 OPCODE(GetRegister,                                         U32,            Reg,                                                                            )
 OPCODE(SetRegister,                                         Void,           Reg,            U32,                                                            )

src/shader_recompiler/frontend/ir/post_order.cpp

@@ -2,6 +2,8 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <algorithm>
+
 #include <boost/container/flat_set.hpp>
 #include <boost/container/small_vector.hpp>
 
@@ -10,35 +12,31 @@
 
 namespace Shader::IR {
 
-BlockList PostOrder(const BlockList& blocks) {
+BlockList PostOrder(const AbstractSyntaxNode& root) {
     boost::container::small_vector<Block*, 16> block_stack;
     boost::container::flat_set<Block*> visited;
-
     BlockList post_order_blocks;
-    post_order_blocks.reserve(blocks.size());
 
-    Block* const first_block{blocks.front()};
+    if (root.type != AbstractSyntaxNode::Type::Block) {
+        throw LogicError("First node in abstract syntax list root is not a block");
+    }
+    Block* const first_block{root.block};
     visited.insert(first_block);
     block_stack.push_back(first_block);
 
-    const auto visit_branch = [&](Block* block, Block* branch) {
-        if (!branch) {
-            return false;
-        }
-        if (!visited.insert(branch).second) {
-            return false;
-        }
-        // Calling push_back twice is faster than insert on MSVC
-        block_stack.push_back(block);
-        block_stack.push_back(branch);
-        return true;
-    };
     while (!block_stack.empty()) {
         Block* const block{block_stack.back()};
+        const auto visit{[&](Block* branch) {
+            if (!visited.insert(branch).second) {
+                return false;
+            }
+            // Calling push_back twice is faster than insert on MSVC
+            block_stack.push_back(block);
+            block_stack.push_back(branch);
+            return true;
+        }};
         block_stack.pop_back();
-
-        if (!visit_branch(block, block->TrueBranch()) &&
-            !visit_branch(block, block->FalseBranch())) {
+        if (std::ranges::none_of(block->ImmSuccessors(), visit)) {
             post_order_blocks.push_back(block);
         }
     }

src/shader_recompiler/frontend/ir/post_order.h

@@ -5,9 +5,10 @@
 #pragma once
 
 #include "shader_recompiler/frontend/ir/basic_block.h"
+#include "shader_recompiler/frontend/ir/abstract_syntax_list.h"
 
 namespace Shader::IR {
 
-BlockList PostOrder(const BlockList& blocks);
+BlockList PostOrder(const AbstractSyntaxNode& root);
 
 } // namespace Shader::IR

src/shader_recompiler/frontend/ir/program.h

@@ -7,8 +7,7 @@
 #include <array>
 #include <string>
 
-#include <boost/container/small_vector.hpp>
-
+#include "shader_recompiler/frontend/ir/abstract_syntax_list.h"
 #include "shader_recompiler/frontend/ir/basic_block.h"
 #include "shader_recompiler/program_header.h"
 #include "shader_recompiler/shader_info.h"
@@ -17,6 +16,7 @@
 namespace Shader::IR {
 
 struct Program {
+    AbstractSyntaxList syntax_list;
     BlockList blocks;
     BlockList post_order_blocks;
     Info info;

src/shader_recompiler/frontend/ir/type.h

@@ -16,31 +16,30 @@ namespace Shader::IR {
 enum class Type {
     Void = 0,
     Opaque = 1 << 0,
-    Label = 1 << 1,
-    Reg = 1 << 2,
-    Pred = 1 << 3,
-    Attribute = 1 << 4,
-    Patch = 1 << 5,
-    U1 = 1 << 6,
-    U8 = 1 << 7,
-    U16 = 1 << 8,
-    U32 = 1 << 9,
-    U64 = 1 << 10,
-    F16 = 1 << 11,
-    F32 = 1 << 12,
-    F64 = 1 << 13,
-    U32x2 = 1 << 14,
-    U32x3 = 1 << 15,
-    U32x4 = 1 << 16,
-    F16x2 = 1 << 17,
-    F16x3 = 1 << 18,
-    F16x4 = 1 << 19,
-    F32x2 = 1 << 20,
-    F32x3 = 1 << 21,
-    F32x4 = 1 << 22,
-    F64x2 = 1 << 23,
-    F64x3 = 1 << 24,
-    F64x4 = 1 << 25,
+    Reg = 1 << 1,
+    Pred = 1 << 2,
+    Attribute = 1 << 3,
+    Patch = 1 << 4,
+    U1 = 1 << 5,
+    U8 = 1 << 6,
+    U16 = 1 << 7,
+    U32 = 1 << 8,
+    U64 = 1 << 9,
+    F16 = 1 << 10,
+    F32 = 1 << 11,
+    F64 = 1 << 12,
+    U32x2 = 1 << 13,
+    U32x3 = 1 << 14,
+    U32x4 = 1 << 15,
+    F16x2 = 1 << 16,
+    F16x3 = 1 << 17,
+    F16x4 = 1 << 18,
+    F32x2 = 1 << 19,
+    F32x3 = 1 << 20,
+    F32x4 = 1 << 21,
+    F64x2 = 1 << 22,
+    F64x3 = 1 << 23,
+    F64x4 = 1 << 24,
 };
 DECLARE_ENUM_FLAG_OPERATORS(Type)
 

src/shader_recompiler/frontend/ir/value.cpp

@@ -9,8 +9,6 @@ namespace Shader::IR {
 
 Value::Value(IR::Inst* value) noexcept : type{Type::Opaque}, inst{value} {}
 
-Value::Value(IR::Block* value) noexcept : type{Type::Label}, label{value} {}
-
 Value::Value(IR::Reg value) noexcept : type{Type::Reg}, reg{value} {}
 
 Value::Value(IR::Pred value) noexcept : type{Type::Pred}, pred{value} {}
@@ -33,10 +31,6 @@ Value::Value(u64 value) noexcept : type{Type::U64}, imm_u64{value} {}
 
 Value::Value(f64 value) noexcept : type{Type::F64}, imm_f64{value} {}
 
-bool Value::IsLabel() const noexcept {
-    return type == Type::Label;
-}
-
 IR::Type Value::Type() const noexcept {
     if (IsPhi()) {
         // The type of a phi node is stored in its flags
@@ -60,8 +54,6 @@ bool Value::operator==(const Value& other) const {
         return true;
     case Type::Opaque:
         return inst == other.inst;
-    case Type::Label:
-        return label == other.label;
     case Type::Reg:
         return reg == other.reg;
     case Type::Pred:

src/shader_recompiler/frontend/ir/value.h

@@ -37,7 +37,6 @@ class Value {
 public:
     Value() noexcept = default;
     explicit Value(IR::Inst* value) noexcept;
-    explicit Value(IR::Block* value) noexcept;
     explicit Value(IR::Reg value) noexcept;
     explicit Value(IR::Pred value) noexcept;
     explicit Value(IR::Attribute value) noexcept;
@@ -54,11 +53,9 @@ public:
     [[nodiscard]] bool IsPhi() const noexcept;
     [[nodiscard]] bool IsEmpty() const noexcept;
     [[nodiscard]] bool IsImmediate() const noexcept;
-    [[nodiscard]] bool IsLabel() const noexcept;
     [[nodiscard]] IR::Type Type() const noexcept;
 
     [[nodiscard]] IR::Inst* Inst() const;
-    [[nodiscard]] IR::Block* Label() const;
     [[nodiscard]] IR::Inst* InstRecursive() const;
     [[nodiscard]] IR::Value Resolve() const;
     [[nodiscard]] IR::Reg Reg() const;
@@ -80,7 +77,6 @@ private:
     IR::Type type{};
     union {
         IR::Inst* inst{};
-        IR::Block* label;
         IR::Reg reg;
         IR::Pred pred;
         IR::Attribute attribute;
@@ -304,11 +300,6 @@ inline IR::Inst* Value::Inst() const {
     return inst;
 }
 
-inline IR::Block* Value::Label() const {
-    DEBUG_ASSERT(type == Type::Label);
-    return label;
-}
-
 inline IR::Inst* Value::InstRecursive() const {
     DEBUG_ASSERT(type == Type::Opaque);
     if (IsIdentity()) {

src/shader_recompiler/frontend/maxwell/program.cpp

@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <ranges>
 #include <vector>
 
 #include "shader_recompiler/frontend/ir/basic_block.h"
@@ -15,6 +16,16 @@
 
 namespace Shader::Maxwell {
 namespace {
+IR::BlockList GenerateBlocks(const IR::AbstractSyntaxList& syntax_list) {
+    auto syntax_blocks{syntax_list | std::views::filter([](const auto& node) {
+                           return node.type == IR::AbstractSyntaxNode::Type::Block;
+                       })};
+    IR::BlockList blocks(std::ranges::distance(syntax_blocks));
+    std::ranges::transform(syntax_blocks, blocks.begin(),
+                           [](const IR::AbstractSyntaxNode& node) { return node.block; });
+    return blocks;
+}
+
 void RemoveUnreachableBlocks(IR::Program& program) {
     // Some blocks might be unreachable if a function call exists unconditionally
     // If this happens the number of blocks and post order blocks will mismatch
@@ -23,7 +34,7 @@ void RemoveUnreachableBlocks(IR::Program& program) {
     }
     const auto begin{program.blocks.begin() + 1};
     const auto end{program.blocks.end()};
-    const auto pred{[](IR::Block* block) { return block->ImmediatePredecessors().empty(); }};
+    const auto pred{[](IR::Block* block) { return block->ImmPredecessors().empty(); }};
     program.blocks.erase(std::remove_if(begin, end, pred), end);
 }
 
@@ -110,8 +121,9 @@ void AddNVNStorageBuffers(IR::Program& program) {
 IR::Program TranslateProgram(ObjectPool<IR::Inst>& inst_pool, ObjectPool<IR::Block>& block_pool,
                              Environment& env, Flow::CFG& cfg) {
     IR::Program program;
-    program.blocks = VisitAST(inst_pool, block_pool, env, cfg);
-    program.post_order_blocks = PostOrder(program.blocks);
+    program.syntax_list = BuildASL(inst_pool, block_pool, env, cfg);
+    program.blocks = GenerateBlocks(program.syntax_list);
+    program.post_order_blocks = PostOrder(program.syntax_list.front());
     program.stage = env.ShaderStage();
     program.local_memory_size = env.LocalMemorySize();
     switch (program.stage) {
@@ -159,9 +171,7 @@ IR::Program MergeDualVertexPrograms(IR::Program& vertex_a, IR::Program& vertex_b
     Optimization::VertexATransformPass(vertex_a);
     Optimization::VertexBTransformPass(vertex_b);
     std::swap(result.blocks, vertex_a.blocks);
-    for (IR::Block* block : vertex_b.blocks) {
-        result.blocks.push_back(block);
-    }
+    result.blocks.insert(result.blocks.end(), vertex_b.blocks.begin(), vertex_b.blocks.end());
     result.stage = Stage::VertexB;
     result.info = vertex_a.info;
     result.local_memory_size = std::max(vertex_a.local_memory_size, vertex_b.local_memory_size);
@@ -173,7 +183,7 @@ IR::Program MergeDualVertexPrograms(IR::Program& vertex_a, IR::Program& vertex_b
     Optimization::JoinTextureInfo(result.info, vertex_b.info);
     Optimization::JoinStorageInfo(result.info, vertex_b.info);
     Optimization::DualVertexJoinPass(result);
-    result.post_order_blocks = PostOrder(result.blocks);
+    result.post_order_blocks = PostOrder(result.syntax_list.front());
     Optimization::DeadCodeEliminationPass(result);
     Optimization::VerificationPass(result);
     Optimization::CollectShaderInfoPass(env_vertex_b, result);

src/shader_recompiler/frontend/maxwell/structured_control_flow.cpp

@@ -36,7 +36,6 @@ using Tree = boost::intrusive::list<Statement,
                                     // Avoid linear complexity on splice, size is never called
                                     boost::intrusive::constant_time_size<false>>;
 using Node = Tree::iterator;
-using ConstNode = Tree::const_iterator;
 
 enum class StatementType {
     Code,
@@ -91,7 +90,8 @@ struct IndirectBranchCond {};
 #pragma warning(disable : 26495) // Always initialize a member variable, expected in Statement
 #endif
 struct Statement : ListBaseHook {
-    Statement(IR::Block* code_, Statement* up_) : code{code_}, up{up_}, type{StatementType::Code} {}
+    Statement(const Flow::Block* block_, Statement* up_)
+        : block{block_}, up{up_}, type{StatementType::Code} {}
     Statement(Goto, Statement* cond_, Node label_, Statement* up_)
         : label{label_}, cond{cond_}, up{up_}, type{StatementType::Goto} {}
     Statement(Label, u32 id_, Statement* up_) : id{id_}, up{up_}, type{StatementType::Label} {}
@@ -125,7 +125,7 @@ struct Statement : ListBaseHook {
     }
 
     union {
-        IR::Block* code;
+        const Flow::Block* block;
         Node label;
         Tree children;
         IR::Condition guest_cond;
@@ -171,8 +171,8 @@ std::string DumpTree(const Tree& tree, u32 indentation = 0) {
         switch (stmt->type) {
         case StatementType::Code:
             ret += fmt::format("{}    Block {:04x} -> {:04x} (0x{:016x});\n", indent,
-                               stmt->code->LocationBegin(), stmt->code->LocationEnd(),
-                               reinterpret_cast<uintptr_t>(stmt->code));
+                               stmt->block->begin, stmt->block->end,
+                               reinterpret_cast<uintptr_t>(stmt->block));
             break;
         case StatementType::Goto:
             ret += fmt::format("{}    if ({}) goto L{};\n", indent, DumpExpr(stmt->cond),
@@ -407,11 +407,7 @@ private:
             }};
             root.push_front(make_reset_variable());
             root.insert(ip, make_reset_variable());
-
-            const u32 begin_offset{block.begin.Offset()};
-            const u32 end_offset{block.end.Offset()};
-            IR::Block* const ir_block{block_pool.Create(inst_pool, begin_offset, end_offset)};
-            root.insert(ip, *pool.Create(ir_block, &root_stmt));
+            root.insert(ip, *pool.Create(&block, &root_stmt));
 
             switch (block.end_class) {
             case Flow::EndClass::Branch: {
@@ -620,13 +616,13 @@ private:
     Statement root_stmt{FunctionTag{}};
 };
 
-IR::Block* TryFindForwardBlock(const Statement& stmt) {
-    const Tree& tree{stmt.up->children};
-    const ConstNode end{tree.cend()};
-    ConstNode forward_node{std::next(Tree::s_iterator_to(stmt))};
+[[nodiscard]] Statement* TryFindForwardBlock(Statement& stmt) {
+    Tree& tree{stmt.up->children};
+    const Node end{tree.end()};
+    Node forward_node{std::next(Tree::s_iterator_to(stmt))};
     while (forward_node != end && !HasChildren(forward_node->type)) {
         if (forward_node->type == StatementType::Code) {
-            return forward_node->code;
+            return &*forward_node;
         }
         ++forward_node;
     }
@@ -654,21 +650,29 @@ class TranslatePass {
 public:
     TranslatePass(ObjectPool<IR::Inst>& inst_pool_, ObjectPool<IR::Block>& block_pool_,
                   ObjectPool<Statement>& stmt_pool_, Environment& env_, Statement& root_stmt,
-                  IR::BlockList& block_list_)
+                  IR::AbstractSyntaxList& syntax_list_)
         : stmt_pool{stmt_pool_}, inst_pool{inst_pool_}, block_pool{block_pool_}, env{env_},
-          block_list{block_list_} {
+          syntax_list{syntax_list_} {
         Visit(root_stmt, nullptr, nullptr);
 
-        IR::Block& first_block{*block_list.front()};
+        IR::Block& first_block{*syntax_list.front().block};
         IR::IREmitter ir{first_block, first_block.begin()};
         ir.Prologue();
     }
 
 private:
-    void Visit(Statement& parent, IR::Block* continue_block, IR::Block* break_block) {
+    void Visit(Statement& parent, IR::Block* break_block, IR::Block* fallthrough_block) {
+        IR::Block* current_block{};
+        const auto ensure_block{[&] {
+            if (current_block) {
+                return;
+            }
+            current_block = block_pool.Create(inst_pool);
+            auto& node{syntax_list.emplace_back()};
+            node.type = IR::AbstractSyntaxNode::Type::Block;
+            node.block = current_block;
+        }};
         Tree& tree{parent.children};
-        IR::Block* current_block{nullptr};
-
         for (auto it = tree.begin(); it != tree.end(); ++it) {
             Statement& stmt{*it};
             switch (stmt.type) {
@@ -676,124 +680,157 @@ private:
                 // Labels can be ignored
                 break;
             case StatementType::Code: {
-                if (current_block && current_block != stmt.code) {
-                    IR::IREmitter{*current_block}.Branch(stmt.code);
-                }
-                current_block = stmt.code;
-                Translate(env, stmt.code);
-                block_list.push_back(stmt.code);
+                ensure_block();
+                Translate(env, current_block, stmt.block->begin.Offset(), stmt.block->end.Offset());
                 break;
             }
             case StatementType::SetVariable: {
-                if (!current_block) {
-                    current_block = MergeBlock(parent, stmt);
-                }
+                ensure_block();
                 IR::IREmitter ir{*current_block};
                 ir.SetGotoVariable(stmt.id, VisitExpr(ir, *stmt.op));
                 break;
             }
             case StatementType::SetIndirectBranchVariable: {
-                if (!current_block) {
-                    current_block = MergeBlock(parent, stmt);
-                }
+                ensure_block();
                 IR::IREmitter ir{*current_block};
                 IR::U32 address{ir.IAdd(ir.GetReg(stmt.branch_reg), ir.Imm32(stmt.branch_offset))};
                 ir.SetIndirectBranchVariable(address);
                 break;
             }
             case StatementType::If: {
-                if (!current_block) {
-                    current_block = block_pool.Create(inst_pool);
-                    block_list.push_back(current_block);
-                }
+                ensure_block();
                 IR::Block* const merge_block{MergeBlock(parent, stmt)};
 
-                // Visit children
-                const size_t first_block_index{block_list.size()};
-                Visit(stmt, merge_block, break_block);
-
                 // Implement if header block
-                IR::Block* const first_if_block{block_list.at(first_block_index)};
                 IR::IREmitter ir{*current_block};
                 const IR::U1 cond{VisitExpr(ir, *stmt.cond)};
-                ir.SelectionMerge(merge_block);
-                ir.BranchConditional(cond, first_if_block, merge_block);
+                ir.BranchConditionRef(cond);
 
+                const size_t if_node_index{syntax_list.size()};
+                syntax_list.emplace_back();
+
+                // Visit children
+                const size_t then_block_index{syntax_list.size()};
+                Visit(stmt, break_block, merge_block);
+
+                IR::Block* const then_block{syntax_list.at(then_block_index).block};
+                current_block->AddBranch(then_block);
+                current_block->AddBranch(merge_block);
                 current_block = merge_block;
+
+                auto& if_node{syntax_list[if_node_index]};
+                if_node.type = IR::AbstractSyntaxNode::Type::If;
+                if_node.if_node.cond = cond;
+                if_node.if_node.body = then_block;
+                if_node.if_node.merge = merge_block;
+
+                auto& endif_node{syntax_list.emplace_back()};
+                endif_node.type = IR::AbstractSyntaxNode::Type::EndIf;
+                endif_node.end_if.merge = merge_block;
+
+                auto& merge{syntax_list.emplace_back()};
+                merge.type = IR::AbstractSyntaxNode::Type::Block;
+                merge.block = merge_block;
                 break;
             }
             case StatementType::Loop: {
                 IR::Block* const loop_header_block{block_pool.Create(inst_pool)};
                 if (current_block) {
-                    IR::IREmitter{*current_block}.Branch(loop_header_block);
+                    current_block->AddBranch(loop_header_block);
                 }
-                block_list.push_back(loop_header_block);
+                auto& header_node{syntax_list.emplace_back()};
+                header_node.type = IR::AbstractSyntaxNode::Type::Block;
+                header_node.block = loop_header_block;
 
-                IR::Block* const new_continue_block{block_pool.Create(inst_pool)};
+                IR::Block* const continue_block{block_pool.Create(inst_pool)};
                 IR::Block* const merge_block{MergeBlock(parent, stmt)};
 
+                const size_t loop_node_index{syntax_list.size()};
+                syntax_list.emplace_back();
+
                 // Visit children
-                const size_t first_block_index{block_list.size()};
-                Visit(stmt, new_continue_block, merge_block);
+                const size_t body_block_index{syntax_list.size()};
+                Visit(stmt, merge_block, continue_block);
 
                 // The continue block is located at the end of the loop
-                block_list.push_back(new_continue_block);
+                IR::IREmitter ir{*continue_block};
+                const IR::U1 cond{VisitExpr(ir, *stmt.cond)};
+                ir.BranchConditionRef(cond);
 
-                // Implement loop header block
-                IR::Block* const first_loop_block{block_list.at(first_block_index)};
-                IR::IREmitter ir{*loop_header_block};
-                ir.LoopMerge(merge_block, new_continue_block);
-                ir.Branch(first_loop_block);
+                IR::Block* const body_block{syntax_list.at(body_block_index).block};
+                loop_header_block->AddBranch(body_block);
 
-                // Implement continue block
-                IR::IREmitter continue_ir{*new_continue_block};
-                const IR::U1 continue_cond{VisitExpr(continue_ir, *stmt.cond)};
-                continue_ir.BranchConditional(continue_cond, ir.block, merge_block);
+                continue_block->AddBranch(loop_header_block);
+                continue_block->AddBranch(merge_block);
 
                 current_block = merge_block;
+
+                auto& loop{syntax_list[loop_node_index]};
+                loop.type = IR::AbstractSyntaxNode::Type::Loop;
+                loop.loop.body = body_block;
+                loop.loop.continue_block = continue_block;
+                loop.loop.merge = merge_block;
+
+                auto& continue_block_node{syntax_list.emplace_back()};
+                continue_block_node.type = IR::AbstractSyntaxNode::Type::Block;
+                continue_block_node.block = continue_block;
+
+                auto& repeat{syntax_list.emplace_back()};
+                repeat.type = IR::AbstractSyntaxNode::Type::Repeat;
+                repeat.repeat.cond = cond;
+                repeat.repeat.loop_header = loop_header_block;
+                repeat.repeat.merge = merge_block;
+
+                auto& merge{syntax_list.emplace_back()};
+                merge.type = IR::AbstractSyntaxNode::Type::Block;
+                merge.block = merge_block;
                 break;
             }
             case StatementType::Break: {
-                if (!current_block) {
-                    current_block = block_pool.Create(inst_pool);
-                    block_list.push_back(current_block);
-                }
+                ensure_block();
                 IR::Block* const skip_block{MergeBlock(parent, stmt)};
 
                 IR::IREmitter ir{*current_block};
-                ir.BranchConditional(VisitExpr(ir, *stmt.cond), break_block, skip_block);
-
+                const IR::U1 cond{VisitExpr(ir, *stmt.cond)};
+                ir.BranchConditionRef(cond);
+                current_block->AddBranch(break_block);
+                current_block->AddBranch(skip_block);
                 current_block = skip_block;
+
+                auto& break_node{syntax_list.emplace_back()};
+                break_node.type = IR::AbstractSyntaxNode::Type::Break;
+                break_node.break_node.cond = cond;
+                break_node.break_node.merge = break_block;
+                break_node.break_node.skip = skip_block;
+
+                auto& merge{syntax_list.emplace_back()};
+                merge.type = IR::AbstractSyntaxNode::Type::Block;
+                merge.block = skip_block;
                 break;
             }
             case StatementType::Return: {
-                if (!current_block) {
-                    current_block = block_pool.Create(inst_pool);
-                    block_list.push_back(current_block);
-                }
-                IR::IREmitter ir{*current_block};
-                ir.Epilogue();
-                ir.Return();
+                ensure_block();
+                IR::IREmitter{*current_block}.Epilogue();
                 current_block = nullptr;
+                syntax_list.emplace_back().type = IR::AbstractSyntaxNode::Type::Return;
                 break;
             }
             case StatementType::Kill: {
-                if (!current_block) {
-                    current_block = block_pool.Create(inst_pool);
-                    block_list.push_back(current_block);
-                }
+                ensure_block();
                 IR::Block* demote_block{MergeBlock(parent, stmt)};
-                IR::IREmitter{*current_block}.DemoteToHelperInvocation(demote_block);
+                IR::IREmitter{*current_block}.DemoteToHelperInvocation();
+                current_block->AddBranch(demote_block);
                 current_block = demote_block;
+
+                auto& merge{syntax_list.emplace_back()};
+                merge.type = IR::AbstractSyntaxNode::Type::Block;
+                merge.block = demote_block;
                 break;
             }
             case StatementType::Unreachable: {
-                if (!current_block) {
-                    current_block = block_pool.Create(inst_pool);
-                    block_list.push_back(current_block);
-                }
-                IR::IREmitter{*current_block}.Unreachable();
+                ensure_block();
                 current_block = nullptr;
+                syntax_list.emplace_back().type = IR::AbstractSyntaxNode::Type::Unreachable;
                 break;
             }
             default:
@@ -801,42 +838,42 @@ private:
             }
         }
         if (current_block) {
-            IR::IREmitter ir{*current_block};
-            if (continue_block) {
-                ir.Branch(continue_block);
+            if (fallthrough_block) {
+                current_block->AddBranch(fallthrough_block);
             } else {
-                ir.Unreachable();
+                syntax_list.emplace_back().type = IR::AbstractSyntaxNode::Type::Unreachable;
             }
         }
     }
 
     IR::Block* MergeBlock(Statement& parent, Statement& stmt) {
-        if (IR::Block* const block{TryFindForwardBlock(stmt)}) {
-            return block;
+        Statement* merge_stmt{TryFindForwardBlock(stmt)};
+        if (!merge_stmt) {
+            // Create a merge block we can visit later
+            merge_stmt = stmt_pool.Create(&dummy_flow_block, &parent);
+            parent.children.insert(std::next(Tree::s_iterator_to(stmt)), *merge_stmt);
         }
-        // Create a merge block we can visit later
-        IR::Block* const block{block_pool.Create(inst_pool)};
-        Statement* const merge_stmt{stmt_pool.Create(block, &parent)};
-        parent.children.insert(std::next(Tree::s_iterator_to(stmt)), *merge_stmt);
-        return block;
+        return block_pool.Create(inst_pool);
     }
 
     ObjectPool<Statement>& stmt_pool;
     ObjectPool<IR::Inst>& inst_pool;
     ObjectPool<IR::Block>& block_pool;
     Environment& env;
-    IR::BlockList& block_list;
+    IR::AbstractSyntaxList& syntax_list;
+    // TODO: Make this constexpr when std::vector is constexpr
+    const Flow::Block dummy_flow_block;
 };
 } // Anonymous namespace
 
-IR::BlockList VisitAST(ObjectPool<IR::Inst>& inst_pool, ObjectPool<IR::Block>& block_pool,
-                       Environment& env, Flow::CFG& cfg) {
+IR::AbstractSyntaxList BuildASL(ObjectPool<IR::Inst>& inst_pool, ObjectPool<IR::Block>& block_pool,
+                                Environment& env, Flow::CFG& cfg) {
     ObjectPool<Statement> stmt_pool{64};
     GotoPass goto_pass{cfg, inst_pool, block_pool, stmt_pool};
     Statement& root{goto_pass.RootStatement()};
-    IR::BlockList block_list;
-    TranslatePass{inst_pool, block_pool, stmt_pool, env, root, block_list};
-    return block_list;
+    IR::AbstractSyntaxList syntax_list;
+    TranslatePass{inst_pool, block_pool, stmt_pool, env, root, syntax_list};
+    return syntax_list;
 }
 
 } // namespace Shader::Maxwell

src/shader_recompiler/frontend/maxwell/structured_control_flow.h

@@ -4,12 +4,8 @@
 
 #pragma once
 
-#include <functional>
-#include <span>
-
-#include <boost/intrusive/list.hpp>
-
 #include "shader_recompiler/environment.h"
+#include "shader_recompiler/frontend/ir/abstract_syntax_list.h"
 #include "shader_recompiler/frontend/ir/basic_block.h"
 #include "shader_recompiler/frontend/ir/value.h"
 #include "shader_recompiler/frontend/maxwell/control_flow.h"
@@ -17,8 +13,8 @@
 
 namespace Shader::Maxwell {
 
-[[nodiscard]] IR::BlockList VisitAST(ObjectPool<IR::Inst>& inst_pool,
-                                     ObjectPool<IR::Block>& block_pool, Environment& env,
-                                     Flow::CFG& cfg);
+[[nodiscard]] IR::AbstractSyntaxList BuildASL(ObjectPool<IR::Inst>& inst_pool,
+                                              ObjectPool<IR::Block>& block_pool, Environment& env,
+                                              Flow::CFG& cfg);
 
 } // namespace Shader::Maxwell

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

@@ -23,13 +23,12 @@ static void Invoke(TranslatorVisitor& visitor, Location pc, u64 insn) {
     }
 }
 
-void Translate(Environment& env, IR::Block* block) {
-    if (block->IsVirtual()) {
+void Translate(Environment& env, IR::Block* block, u32 location_begin, u32 location_end) {
+    if (location_begin == location_end) {
         return;
     }
     TranslatorVisitor visitor{env, *block};
-    const Location pc_end{block->LocationEnd()};
-    for (Location pc = block->LocationBegin(); pc != pc_end; ++pc) {
+    for (Location pc = location_begin; pc != location_end; ++pc) {
         const u64 insn{env.ReadInstruction(pc.Offset())};
         const Opcode opcode{Decode(insn)};
         switch (opcode) {

src/shader_recompiler/frontend/maxwell/translate/translate.h

@@ -9,6 +9,6 @@
 
 namespace Shader::Maxwell {
 
-void Translate(Environment& env, IR::Block* block);
+void Translate(Environment& env, IR::Block* block, u32 location_begin, u32 location_end);
 
 } // namespace Shader::Maxwell

src/shader_recompiler/ir_opt/constant_propagation_pass.cpp

@@ -353,24 +353,6 @@ IR::Value EvalImmediates(const IR::Inst& inst, Func&& func, std::index_sequence<
     return IR::Value{func(Arg<typename Traits::template ArgType<I>>(inst.Arg(I))...)};
 }
 
-void FoldBranchConditional(IR::Inst& inst) {
-    const IR::U1 cond{inst.Arg(0)};
-    if (cond.IsImmediate()) {
-        // TODO: Convert to Branch
-        return;
-    }
-    const IR::Inst* cond_inst{cond.InstRecursive()};
-    if (cond_inst->GetOpcode() == IR::Opcode::LogicalNot) {
-        const IR::Value true_label{inst.Arg(1)};
-        const IR::Value false_label{inst.Arg(2)};
-        // Remove negation on the conditional (take the parameter out of LogicalNot) and swap
-        // the branches
-        inst.SetArg(0, cond_inst->Arg(0));
-        inst.SetArg(1, false_label);
-        inst.SetArg(2, true_label);
-    }
-}
-
 std::optional<IR::Value> FoldCompositeExtractImpl(IR::Value inst_value, IR::Opcode insert,
                                                   IR::Opcode construct, u32 first_index) {
     IR::Inst* const inst{inst_value.InstRecursive()};
@@ -581,8 +563,6 @@ void ConstantPropagation(IR::Block& block, IR::Inst& inst) {
             return (base & ~(~(~0u << bits) << offset)) | (insert << offset);
         });
         return;
-    case IR::Opcode::BranchConditional:
-        return FoldBranchConditional(inst);
     case IR::Opcode::CompositeExtractF32x2:
         return FoldCompositeExtract(inst, IR::Opcode::CompositeConstructF32x2,
                                     IR::Opcode::CompositeInsertF32x2);

src/shader_recompiler/ir_opt/dual_vertex_pass.cpp

@@ -13,60 +13,16 @@
 
 namespace Shader::Optimization {
 
-void VertexATransformPass(IR::Program& program) {
-    bool replaced_join{};
-    bool eliminated_epilogue{};
-    for (IR::Block* const block : program.post_order_blocks) {
-        for (IR::Inst& inst : block->Instructions()) {
-            switch (inst.GetOpcode()) {
-            case IR::Opcode::Return:
-                inst.ReplaceOpcode(IR::Opcode::Join);
-                replaced_join = true;
-                break;
-            case IR::Opcode::Epilogue:
-                inst.Invalidate();
-                eliminated_epilogue = true;
-                break;
-            default:
-                break;
-            }
-            if (replaced_join && eliminated_epilogue) {
-                return;
-            }
-        }
-    }
+void VertexATransformPass(IR::Program&) {
+    throw NotImplementedException("VertexA pass");
 }
 
-void VertexBTransformPass(IR::Program& program) {
-    for (IR::Block* const block : program.blocks) {
-        for (IR::Inst& inst : block->Instructions()) {
-            if (inst.GetOpcode() == IR::Opcode::Prologue) {
-                return inst.Invalidate();
-            }
-        }
-    }
+void VertexBTransformPass(IR::Program&) {
+    throw NotImplementedException("VertexA pass");
 }
 
-void DualVertexJoinPass(IR::Program& program) {
-    const auto& blocks = program.blocks;
-    const s64 sub_size = static_cast<s64>(blocks.size()) - 1;
-    if (sub_size < 1) {
-        throw LogicError("Dual Vertex Join pass failed, expected atleast 2 blocks");
-    }
-    for (s64 index = 0; index < sub_size; ++index) {
-        IR::Block* const current_block{blocks[index]};
-        IR::Block* const next_block{blocks[index + 1]};
-        for (IR::Inst& inst : current_block->Instructions()) {
-            if (inst.GetOpcode() == IR::Opcode::Join) {
-                IR::IREmitter ir{*current_block, IR::Block::InstructionList::s_iterator_to(inst)};
-                ir.Branch(next_block);
-                inst.Invalidate();
-                // Only 1 join should exist
-                return;
-            }
-        }
-    }
-    throw LogicError("Dual Vertex Join pass failed, no join present");
+void DualVertexJoinPass(IR::Program&) {
+    throw NotImplementedException("VertexA pass");
 }
 
 } // namespace Shader::Optimization

src/shader_recompiler/ir_opt/identity_removal_pass.cpp

@@ -12,7 +12,6 @@ namespace Shader::Optimization {
 
 void IdentityRemovalPass(IR::Program& program) {
     std::vector<IR::Inst*> to_invalidate;
-
     for (IR::Block* const block : program.blocks) {
         for (auto inst = block->begin(); inst != block->end();) {
             const size_t num_args{inst->NumArgs()};

src/shader_recompiler/ir_opt/ssa_rewrite_pass.cpp

@@ -202,7 +202,7 @@ public:
 
                     incomplete_phis[block].insert_or_assign(variable, phi);
                     stack.back().result = IR::Value{&*phi};
-                } else if (const std::span imm_preds{block->ImmediatePredecessors()};
+                } else if (const std::span imm_preds = block->ImmPredecessors();
                            imm_preds.size() == 1) {
                     // Optimize the common case of one predecessor: no phi needed
                     stack.back().pc = Status::SetValue;
@@ -257,7 +257,7 @@ public:
 private:
     template <typename Type>
     IR::Value AddPhiOperands(Type variable, IR::Inst& phi, IR::Block* block) {
-        for (IR::Block* const imm_pred : block->ImmediatePredecessors()) {
+        for (IR::Block* const imm_pred : block->ImmPredecessors()) {
             phi.AddPhiOperand(imm_pred, ReadVariable(variable, imm_pred));
         }
         return TryRemoveTrivialPhi(phi, block, UndefOpcode(variable));