support disabling ALIASING_FUNCTION_POINTERS in fastcomp

2 files changed, 49 insertions, 0 deletions

diff --git a/emscripten.py b/emscripten.py
index c8fab3be..835b1ec9 100755
--- a/emscripten.py
+++ b/emscripten.py
@@ -748,6 +748,8 @@ def emscript_fast(infile, settings, outfile, libraries=[], compiler_engine=None,
     backend_args += ['-emscripten-reserved-function-pointers=%d' % settings['RESERVED_FUNCTION_POINTERS']]
   if settings['ASSERTIONS'] > 0:
     backend_args += ['-emscripten-assertions=%d' % settings['ASSERTIONS']]
+  if settings['ALIASING_FUNCTION_POINTERS'] == 0:
+    backend_args += ['-emscripten-no-aliasing-function-pointers']
   backend_args += ['-O' + str(settings['OPT_LEVEL'])]
   if DEBUG:
     logging.debug('emscript: llvm backend: ' + ' '.join(backend_args))
diff --git a/tests/test_other.py b/tests/test_other.py
index 4b5ed666..0721bb35 100644
--- a/tests/test_other.py
+++ b/tests/test_other.py
@@ -2741,3 +2741,50 @@ int main() {
           else:
             assert 'abort()' in output, output
 
+  def test_aliased_func_pointers(self):
+    open('src.cpp', 'w').write(r'''
+#include <stdio.h>
+
+int impl1(int foo) { return foo; }
+float impla(float foo) { return foo; }
+int impl2(int foo) { return foo+1; }
+float implb(float foo) { return foo+1; }
+int impl3(int foo) { return foo+2; }
+float implc(float foo) { return foo+2; }
+
+int main(int argc, char **argv) {
+  volatile void *f = (void*)impl1;
+  if (argc == 50) f = (void*)impla;
+  if (argc == 51) f = (void*)impl2;
+  if (argc == 52) f = (void*)implb;
+  if (argc == 53) f = (void*)impl3;
+  if (argc == 54) f = (void*)implc;
+  return (int)f;
+}
+''')
+
+    print 'aliasing'
+
+    sizes_ii = {}
+    sizes_dd = {}
+  
+    for alias in [None, 0, 1]:
+      cmd = [PYTHON, EMCC, 'src.cpp', '-O1']
+      if alias is not None:
+        cmd += ['-s', 'ALIASING_FUNCTION_POINTERS=' + str(alias)]
+      else:
+        alias = -1
+      print cmd
+      Popen(cmd).communicate()
+      src = open('a.out.js').read().split('\n')
+      for line in src:
+        if line.strip().startswith('var FUNCTION_TABLE_ii = '):
+          sizes_ii[alias] = line.count(',')
+        if line.strip().startswith('var FUNCTION_TABLE_dd = '):
+          sizes_dd[alias] = line.count(',')
+
+    for sizes in [sizes_ii, sizes_dd]:
+      assert sizes[-1] == 3 # default - let them alias
+      assert sizes[0] == 7 # no aliasing, all unique, fat tables
+      assert sizes[1] == 3 # aliased once more
+