Merge pull request #559 from stechz/incoming

Bitshift optimizer anticipates fns with switches

AUTHORS

@@ -34,4 +34,5 @@ a license to everyone to use it as detailed in LICENSE.)
 * Andrea Bedini <andrea.bedini@gmail.com>
 * James Pike <totoro.friend@chilon.net>
 * Mokhtar Naamani <mokhtar.naamani@gmail.com>
+* Benjamin Stover <benjamin.stover@gmail.com>
 

tests/runner.py

@@ -7520,6 +7520,9 @@ f.close()
          ['simplifyExpressionsPre', 'optimizeShiftsConservative']),
         (path_from_root('tools', 'test-js-optimizer-t2.js'), open(path_from_root('tools', 'test-js-optimizer-t2-output.js')).read(),
          ['simplifyExpressionsPre', 'optimizeShiftsAggressive']),
+        # Make sure that optimizeShifts handles functions with shift statements.
+        (path_from_root('tools', 'test-js-optimizer-t3.js'), open(path_from_root('tools', 'test-js-optimizer-t3.js')).read(),
+         ['optimizeShiftsAggressive']),
         (path_from_root('tools', 'test-js-optimizer-regs.js'), open(path_from_root('tools', 'test-js-optimizer-regs-output.js')).read(),
          ['registerize']),
       ]:

tools/js-optimizer.js

@@ -485,13 +485,20 @@ function optimizeShiftsInternal(ast, conservative) {
       }
       // vars
       // XXX if var has >>=, ignore it here? That means a previous pass already optimized it
-      traverse(fun, function(node, type) {
+      var hasSwitch = traverse(fun, function(node, type) {
         if (type == 'var') {
           node[1].forEach(function(arg) {
             newVar(arg[0], false, arg[1]);
           });
+        } else if (type == 'switch') {
+          // The relooper can't always optimize functions, and we currently don't work with
+          // switch statements when optimizing shifts. Bail.
+          return true;
         }
       });
+      if (hasSwitch) {
+        break;
+      }
       // uses and defs TODO: weight uses by being inside a loop (powers). without that, we
       // optimize for code size, not speed.
       traverse(fun, function(node, type, stack) {

tools/test-js-optimizer-t3.js

@@ -0,0 +1,49 @@
+function _png_create_write_struct_2($user_png_ver, $error_ptr, $error_fn, $warn_fn, $mem_ptr, $malloc_fn, $free_fn) {
+  var $png_ptr$s2;
+  var __label__;
+  __label__ = 2;
+  var setjmpTable = {
+    "2": (function(value) {
+      __label__ = 5;
+      $call1 = value;
+    }),
+    dummy: 0
+  };
+  while (1) try {
+    switch (__label__) {
+     case 2:
+      var $png_ptr;
+      var $call = _png_create_struct(1);
+      $png_ptr = $call;
+      var $call1 = (HEAP32[$png_ptr >> 2] = __label__, 0);
+      __label__ = 5;
+      break;
+     case 5:
+      var $2 = $png_ptr;
+      if (($call1 | 0) == 0) {
+        __label__ = 4;
+        break;
+      } else {
+        __label__ = 3;
+        break;
+      }
+     case 3:
+      var $4 = HEAP32[($png_ptr >> 2) + (148 >> 2)];
+      _png_free($2, $4);
+      HEAP32[($png_ptr >> 2) + (148 >> 2)] = 0;
+      _png_destroy_struct($png_ptr);
+      var $retval_0 = 0;
+      __label__ = 4;
+      break;
+     case 4:
+      var $retval_0;
+      return $retval_0;
+     default:
+      assert(0, "bad label: " + __label__);
+    }
+  } catch (e) {
+    if (!e.longjmp) throw e;
+    setjmpTable[e.label](e.value);
+  }
+}
+// EMSCRIPTEN_GENERATED_FUNCTIONS: ["_png_create_write_struct_2"]