optimize pow (#934)

* optimize pow(x,2) => x*x

* optimize pow(x, 0.5) => sqrt(x)

1 files changed, 47 insertions, 0 deletions

diff --git a/src/ast/localize.h b/src/ast/localize.h
new file mode 100644
index 000000000..9e7dd6653
--- /dev/null
+++ b/src/ast/localize.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2016 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_ast_localizer_h
+#define wasm_ast_localizer_h
+
+#include <wasm-builder.h>
+
+namespace wasm {
+
+// Make an expression available in a local. If already in one, just
+// use that local, otherwise use a new local
+
+struct Localizer {
+  Index index;
+  Expression* expr;
+
+  Localizer(Expression* input, Function* func, Module* wasm) {
+    expr = input;
+    if (auto* get = expr->dynCast<GetLocal>()) {
+      index = get->index;
+    } else if (auto* set = expr->dynCast<SetLocal>()) {
+      index = set->index;
+    } else {
+      index = Builder::addVar(func, expr->type);
+      expr = Builder(*wasm).makeTeeLocal(index, expr);
+    }
+  }
+};
+
+} // namespace wasm
+
+#endif // wasm_ast_localizer_h
+