Shader_IR: allow else derivation to be optional.

src/video_core/renderer_vulkan/vk_shader_decompiler.cpp

@@ -1667,7 +1667,8 @@ public:
     }
 
     void operator()(VideoCommon::Shader::ExprVar& expr) {
-        current_id = decomp.Emit(decomp.OpLoad(decomp.t_bool, decomp.flow_variables.at(expr.var_index)));
+        current_id =
+            decomp.Emit(decomp.OpLoad(decomp.t_bool, decomp.flow_variables.at(expr.var_index)));
     }
 
     void operator()(VideoCommon::Shader::ExprBoolean& expr) {
@@ -1749,7 +1750,8 @@ public:
         const Id loop_end_block = decomp.OpLabel();
         current_loop_exit = endloop_label;
         decomp.Emit(loop_label);
-        decomp.Emit(decomp.OpLoopMerge(endloop_label, loop_end_block, spv::LoopControlMask::MaskNone));
+        decomp.Emit(
+            decomp.OpLoopMerge(endloop_label, loop_end_block, spv::LoopControlMask::MaskNone));
         decomp.Emit(decomp.OpBranch(loop_start_block));
         decomp.Emit(loop_start_block);
         ASTNode current = ast.nodes.GetFirst();

src/video_core/shader/ast.cpp

@@ -363,7 +363,8 @@ std::string ASTManager::Print() {
     return printer.GetResult();
 }
 
-ASTManager::ASTManager(bool full_decompile) : full_decompile{full_decompile} {};
+ASTManager::ASTManager(bool full_decompile, bool disable_else_derivation)
+    : full_decompile{full_decompile}, disable_else_derivation{disable_else_derivation} {};
 
 ASTManager::~ASTManager() {
     Clear();
@@ -378,7 +379,8 @@ void ASTManager::Init() {
 ASTManager::ASTManager(ASTManager&& other)
     : labels_map(std::move(other.labels_map)), labels_count{other.labels_count},
       gotos(std::move(other.gotos)), labels(std::move(other.labels)), variables{other.variables},
-      program{other.program}, main_node{other.main_node}, false_condition{other.false_condition} {
+      program{other.program}, main_node{other.main_node}, false_condition{other.false_condition},
+      disable_else_derivation{other.disable_else_derivation} {
     other.main_node.reset();
 }
 
@@ -392,6 +394,7 @@ ASTManager& ASTManager::operator=(ASTManager&& other) {
     program = other.program;
     main_node = other.main_node;
     false_condition = other.false_condition;
+    disable_else_derivation = other.disable_else_derivation;
 
     other.main_node.reset();
     return *this;
@@ -641,7 +644,7 @@ void ASTManager::EncloseIfThen(ASTNode goto_node, ASTNode label) {
     ASTNode prev = goto_node->GetPrevious();
     Expr condition = goto_node->GetGotoCondition();
     bool do_else = false;
-    if (prev->IsIfThen()) {
+    if (!disable_else_derivation && prev->IsIfThen()) {
         Expr if_condition = prev->GetIfCondition();
         do_else = ExprAreEqual(if_condition, condition);
     }

src/video_core/shader/ast.h

@@ -298,7 +298,7 @@ private:
 
 class ASTManager final {
 public:
-    ASTManager(bool full_decompile);
+    ASTManager(bool full_decompile, bool disable_else_derivation);
     ~ASTManager();
 
     ASTManager(const ASTManager& o) = delete;
@@ -378,6 +378,7 @@ private:
     }
 
     bool full_decompile{};
+    bool disable_else_derivation{};
     std::unordered_map<u32, u32> labels_map{};
     u32 labels_count{};
     std::vector<ASTNode> labels{};

src/video_core/shader/compiler_settings.h

@@ -19,7 +19,8 @@ enum class CompileDepth : u32 {
 std::string CompileDepthAsString(CompileDepth cd);
 
 struct CompilerSettings {
-    CompileDepth depth;
+    CompileDepth depth{CompileDepth::NoFlowStack};
+    bool disable_else_derivation{true};
 };
 
 } // namespace VideoCommon::Shader

src/video_core/shader/control_flow.cpp

@@ -516,7 +516,8 @@ std::unique_ptr<ShaderCharacteristics> ScanFlow(const ProgramCode& program_code,
     std::sort(state.block_info.begin(), state.block_info.end(),
               [](const BlockInfo& a, const BlockInfo& b) -> bool { return a.start < b.start; });
     if (decompiled && settings.depth != CompileDepth::NoFlowStack) {
-        ASTManager manager{settings.depth != CompileDepth::DecompileBackwards};
+        ASTManager manager{settings.depth != CompileDepth::DecompileBackwards,
+                           settings.disable_else_derivation};
         state.manager = &manager;
         DecompileShader(state);
         decompiled = state.manager->IsFullyDecompiled();

src/video_core/shader/control_flow.h

@@ -72,7 +72,7 @@ struct ShaderCharacteristics {
     std::set<u32> labels{};
     u32 start{};
     u32 end{};
-    ASTManager manager{true};
+    ASTManager manager{true, true};
     CompilerSettings settings{};
 };
 

src/video_core/shader/shader_ir.cpp

@@ -25,7 +25,7 @@ using Tegra::Shader::Register;
 ShaderIR::ShaderIR(const ProgramCode& program_code, u32 main_offset, const std::size_t size,
                    CompilerSettings settings)
     : program_code{program_code}, main_offset{main_offset}, program_size{size}, basic_blocks{},
-      program_manager{true}, settings{settings} {
+      program_manager{true, true}, settings{settings} {
     Decode();
 }