Merge pull request #10699 from liamwhite/conditional-barrier

shader_recompiler: remove barriers in conditional control flow when device lacks support

src/shader_recompiler/CMakeLists.txt

@@ -216,6 +216,7 @@ add_library(shader_recompiler STATIC
     frontend/maxwell/translate_program.h
     host_translate_info.h
     ir_opt/collect_shader_info_pass.cpp
+    ir_opt/conditional_barrier_pass.cpp
     ir_opt/constant_propagation_pass.cpp
     ir_opt/dead_code_elimination_pass.cpp
     ir_opt/dual_vertex_pass.cpp

src/shader_recompiler/frontend/maxwell/translate_program.cpp

@@ -289,6 +289,9 @@ IR::Program TranslateProgram(ObjectPool<IR::Inst>& inst_pool, ObjectPool<IR::Blo
     if (!host_info.support_int64) {
         Optimization::LowerInt64ToInt32(program);
     }
+    if (!host_info.support_conditional_barrier) {
+        Optimization::ConditionalBarrierPass(program);
+    }
     Optimization::SsaRewritePass(program);
 
     Optimization::ConstantPropagationPass(env, program);

src/shader_recompiler/host_translate_info.h

@@ -18,6 +18,8 @@ struct HostTranslateInfo {
     bool support_viewport_index_layer{}; ///< True when the device supports gl_Layer in VS
     bool support_geometry_shader_passthrough{}; ///< True when the device supports geometry
                                                 ///< passthrough shaders
+    bool support_conditional_barrier{}; ///< True when the device supports barriers in conditional
+                                        ///< control flow
 };
 
 } // namespace Shader

src/shader_recompiler/ir_opt/conditional_barrier_pass.cpp

@@ -0,0 +1,44 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "shader_recompiler/frontend/ir/program.h"
+#include "shader_recompiler/ir_opt/passes.h"
+
+namespace Shader::Optimization {
+
+void ConditionalBarrierPass(IR::Program& program) {
+    s32 conditional_control_flow_count{0};
+    s32 conditional_return_count{0};
+    for (IR::AbstractSyntaxNode& node : program.syntax_list) {
+        switch (node.type) {
+        case IR::AbstractSyntaxNode::Type::If:
+        case IR::AbstractSyntaxNode::Type::Loop:
+            conditional_control_flow_count++;
+            break;
+        case IR::AbstractSyntaxNode::Type::EndIf:
+        case IR::AbstractSyntaxNode::Type::Repeat:
+            conditional_control_flow_count--;
+            break;
+        case IR::AbstractSyntaxNode::Type::Unreachable:
+        case IR::AbstractSyntaxNode::Type::Return:
+            if (conditional_control_flow_count > 0) {
+                conditional_return_count++;
+            }
+            break;
+        case IR::AbstractSyntaxNode::Type::Block:
+            for (IR::Inst& inst : node.data.block->Instructions()) {
+                if ((conditional_control_flow_count > 0 || conditional_return_count > 0) &&
+                    inst.GetOpcode() == IR::Opcode::Barrier) {
+                    LOG_WARNING(Shader, "Barrier within conditional control flow");
+                    inst.ReplaceOpcode(IR::Opcode::Identity);
+                }
+            }
+            break;
+        default:
+            break;
+        }
+    }
+    ASSERT(conditional_control_flow_count == 0);
+}
+
+} // namespace Shader::Optimization

src/shader_recompiler/ir_opt/passes.h

@@ -13,6 +13,7 @@ struct HostTranslateInfo;
 namespace Shader::Optimization {
 
 void CollectShaderInfoPass(Environment& env, IR::Program& program);
+void ConditionalBarrierPass(IR::Program& program);
 void ConstantPropagationPass(Environment& env, IR::Program& program);
 void DeadCodeEliminationPass(IR::Program& program);
 void GlobalMemoryToStorageBufferPass(IR::Program& program);