Teach buildFlowGraph about functions that are known to always throw.

It can treat calls to these functions like a jump to function exit,
allowing for more accurate tracking of dead junctions.

2 files changed, 9 insertions, 2 deletions

diff --git a/tests/test_core.py b/tests/test_core.py
index d0de0031..bbc6370a 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -1158,8 +1158,6 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
     self.do_run_from_file(src, output)
 
   def test_longjmp_throw(self):
-    if self.run_name == 'asm3': return self.skip('issue 2069') # FIXME
-
     for disable_throw in [0, 1]:
       print disable_throw
       Settings.DISABLE_EXCEPTION_CATCHING = disable_throw
diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index adffc184..d12f4f4d 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -140,6 +140,8 @@ var ALTER_FLOW = set('break', 'continue', 'return');
 var BREAK_CAPTURERS = set('do', 'while', 'for', 'switch');
 var CONTINUE_CAPTURERS = LOOP;
 
+var FUNCTIONS_THAT_ALWAYS_THROW = set('abort', '___resumeException', '___cxa_throw', '___cxa_rethrow');
+
 var NULL_NODE = ['name', 'null'];
 var UNDEFINED_NODE = ['unary-prefix', 'void', ['num', 0]];
 var TRUE_NODE = ['unary-prefix', '!', ['num', 0]];
@@ -2579,6 +2581,13 @@ function registerizeHarder(ast) {
             }
           }
           isInExpr--;
+          // If the call is statically known to throw,
+          // treat it as a jump to function exit.
+          if (!isInExpr && node[1][0] === 'name') {
+            if (node[1][1] in FUNCTIONS_THAT_ALWAYS_THROW) {
+              markNonLocalJump('return');
+            }
+          }
           break;
         case 'seq':
         case 'sub':