Merge pull request #6585 from ameerj/hades

Shader Decompiler Rewrite

1 files changed, 26 insertions, 0 deletions

diff --git a/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp b/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp
new file mode 100644
index 000000000..400836301
--- /dev/null
+++ b/src/shader_recompiler/ir_opt/dead_code_elimination_pass.cpp
@@ -0,0 +1,26 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include "shader_recompiler/frontend/ir/basic_block.h"
+#include "shader_recompiler/frontend/ir/value.h"
+#include "shader_recompiler/ir_opt/passes.h"
+
+namespace Shader::Optimization {
+
+void DeadCodeEliminationPass(IR::Program& program) {
+    // We iterate over the instructions in reverse order.
+    // This is because removing an instruction reduces the number of uses for earlier instructions.
+    for (IR::Block* const block : program.post_order_blocks) {
+        auto it{block->end()};
+        while (it != block->begin()) {
+            --it;
+            if (!it->HasUses() && !it->MayHaveSideEffects()) {
+                it->Invalidate();
+                it = block->Instructions().erase(it);
+            }
+        }
+    }
+}
+
+} // namespace Shader::Optimization