Migrate to wast as source for polyfills

Author: Mauro Bringolf

packages/proposal-sign-extension-ops/src/index.js

@@ -1,20 +1,33 @@
 import { traverse, callInstruction, numberLiteral } from "@webassemblyjs/ast";
-import i32_extend8_s from "./polyfills/i32_extend8_s.json";
-import i32_extend16_s from "./polyfills/i32_extend16_s.json";
-import i64_extend8_s from "./polyfills/i64_extend8_s.json";
-import i64_extend16_s from "./polyfills/i64_extend16_s.json";
-import i64_extend32_s from "./polyfills/i64_extend32_s.json";
+import { parse } from "@webassemblyjs/wast-parser";
+import { readFileSync } from "fs";
+import path from "path";
+
+const funcFromWast = sourcePath => {
+  const ast = parse(readFileSync(sourcePath, "utf8"));
+  return ast.body[0].fields.find(f => f.type === "Func");
+};
 
 class Polyfills {
   constructor(startIndex) {
     this.startIndex = startIndex;
 
     this.asts = {
-      i32_extend8_s,
-      i32_extend16_s,
-      i64_extend8_s,
-      i64_extend16_s,
-      i64_extend32_s
+      i32_extend8_s: funcFromWast(
+        path.join(__dirname, "/polyfills/i32_extend8_s.wast")
+      ),
+      i32_extend16_s: funcFromWast(
+        path.join(__dirname, "/polyfills/i32_extend16_s.wast")
+      ),
+      i64_extend8_s: funcFromWast(
+        path.join(__dirname, "/polyfills/i64_extend8_s.wast")
+      ),
+      i64_extend16_s: funcFromWast(
+        path.join(__dirname, "/polyfills/i64_extend16_s.wast")
+      ),
+      i64_extend32_s: funcFromWast(
+        path.join(__dirname, "/polyfills/i64_extend32_s.wast")
+      )
     };
 
     this.instructions = Object.keys(this.asts);

packages/proposal-sign-extension-ops/src/polyfills/i32_extend16_s.json

@@ -0,0 +1,16 @@
+(module
+  (type (func (param i32) (result i32)))
+  (func $packages/proposal-sign-extension-ops/src/polyfills/i32_extend16_s/i32_extend16_s (param i32) (result i32)
+    (get_local 0)
+    (i32.const -32768)
+    (i32.or)
+    (get_local 0)
+    (i32.const 32767)
+    (i32.and)
+    (get_local 0)
+    (i32.const 32768)
+    (i32.and)
+    (select)
+  )
+  (export "i32_extend16_s" (func $packages/proposal-sign-extension-ops/src/polyfills/i32_extend16_s/i32_extend16_s))
+)