Refactor expression runner so it can be used via the C and JS APIs (#2702)

Refactors most of the precompute pass's expression runner into its
base class so it can also be used via the C and JS APIs. Also adds
the option to populate the runner with known constant local and global
values upfront, and remembers assigned intermediate values as well
as traversing into functions if requested.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/js/binaryen.js-post.js b/src/js/binaryen.js-post.js
index 44dc7174b..7bd88fadc 100644
--- a/src/js/binaryen.js-post.js
+++ b/src/js/binaryen.js-post.js
@@ -485,6 +485,13 @@ function initializeConstants() {
   ].forEach(function(name) {
     Module['SideEffects'][name] = Module['_BinaryenSideEffect' + name]();
   });
+
+  // ExpressionRunner flags
+  Module['ExpressionRunner']['Flags'] = {
+    'Default': Module['_ExpressionRunnerFlagsDefault'](),
+    'PreserveSideeffects': Module['_ExpressionRunnerFlagsPreserveSideeffects'](),
+    'TraverseCalls': Module['_ExpressionRunnerFlagsTraverseCalls']()
+  };
 }
 
 // 'Module' interface
@@ -2427,6 +2434,24 @@ Module['Relooper'] = function(module) {
   };
 };
 
+// 'ExpressionRunner' interface
+Module['ExpressionRunner'] = function(module, flags, maxDepth, maxLoopIterations) {
+  var runner = Module['_ExpressionRunnerCreate'](module['ptr'], flags, maxDepth, maxLoopIterations);
+  this['ptr'] = runner;
+
+  this['setLocalValue'] = function(index, valueExpr) {
+    return Boolean(Module['_ExpressionRunnerSetLocalValue'](runner, index, valueExpr));
+  };
+  this['setGlobalValue'] = function(name, valueExpr) {
+    return preserveStack(function() {
+      return Boolean(Module['_ExpressionRunnerSetGlobalValue'](runner, strToStack(name), valueExpr));
+    });
+  };
+  this['runAndDispose'] = function(expr) {
+    return Module['_ExpressionRunnerRunAndDispose'](runner, expr);
+  };
+};
+
 function getAllNested(ref, numFn, getFn) {
   var num = numFn(ref);
   var ret = new Array(num);