Gecko [ fernandoquevedodop.com ]

Name	Size	Permission
type-checker	[ DIR ]	drwxr-xr-x
duplicated-exports.js	734 B	-rw-r--r--
import-order.js	1.38 KB	-rw-r--r--
imports.js	548 B	-rw-r--r--
index.js	2.57 KB	-rw-r--r--
is-const.js	1.32 KB	-rw-r--r--
type-checker.js	9.14 KB	-rw-r--r--
type-inference.js	1.9 KB	-rw-r--r--

Code Editor : is-const.js

import { traverse } from "@webassemblyjs/ast";
/**
 * Determine if a sequence of instructions form a constant expression
 *
 * See https://webassembly.github.io/spec/core/multipage/valid/instructions.html#valid-constant
 */

export default function isConst(ast, moduleContext) {
  function isConstInstruction(instr) {
    if (instr.id === "const") {
      return true;
    }

if (instr.id === "get_global") {
      var index = instr.args[0].value;
      return !moduleContext.isMutableGlobal(index);
    }

if (instr.id === "end") {
      return true;
    }

return false;
  }

var errors = [];
  traverse(ast, {
    Global: function Global(path) {
      var isValid = path.node.init.reduce(function (acc, instr) {
        return acc && isConstInstruction(instr);
      }, true);

if (!isValid) {
        errors.push("constant expression required: initializer expression cannot reference mutable global");
      } // check type
      // FIXME(sven): this is a quick fix but should ideally go through our
      // stacky type checker

if (path.node.init.length > 0) {
        var type = path.node.globalType.valtype;
        var initType = path.node.init[0].object;

if (initType && type !== initType) {
          errors.push("type mismatch in global initializer");
        }
      }
    }
  });
  return errors;
}

${this.title}

Code Editor : is-const.js