1 files changed, 51 insertions, 0 deletions
diff --git a/src/passes/LowerIfElse.cpp b/src/passes/LowerIfElse.cpp
new file mode 100644
index 000000000..ff84c6844
--- /dev/null
+++ b/src/passes/LowerIfElse.cpp
@@ -0,0 +1,51 @@
+//
+// Lowers if (x) y else z into
+//
+// L: {
+//   if (x) break (y) L
+//   z
+// }
+//
+// This is useful for investigating how beneficial if_else is.
+//
+
+#include <memory>
+
+#include <wasm.h>
+#include <pass.h>
+
+namespace wasm {
+
+struct LowerIfElse : public Pass {
+  LowerIfElse() : Pass("lower-if-else") {}
+
+  MixedArena* allocator;
+  std::unique_ptr<NameManager> namer;
+
+  void prepare(PassRunner* runner, Module *module) override {
+    allocator = runner->allocator;
+    namer = std::unique_ptr<NameManager>(new NameManager());
+    namer->run(runner, module);
+  }
+
+  void visitIf(If *curr) override {
+    if (curr->ifFalse) {
+      auto block = allocator->alloc<Block>();
+      auto name = namer->getUnique("L"); // TODO: getUniqueInFunction
+      block->name = name;
+      block->list.push_back(curr);
+      block->list.push_back(curr->ifFalse);
+      curr->ifFalse = nullptr;
+      auto break_ = allocator->alloc<Break>();
+      break_->name = name;
+      break_->value = curr->ifTrue;
+      curr->ifTrue = break_;
+      replaceCurrent(block);
+    }
+  }
+};
+
+static RegisterPass<LowerIfElse> registerPass;
+
+} // namespace wasm
+