support -Os and -Oz as arguments to emcc

emcc

@@ -161,9 +161,17 @@ Options that are modified or new in %s include:
                            time in return for the smallest and fastest
                            output.
 
-  -O3                      As -O2, plus additional optimizations that can
+  -Os                      Like -O2 with extra optimizations for size.
+
+  -Oz                      Like -Os but reduces code size further.
+
+  -O3                      Like -O2 plus additional JS optimizations that can
                            take a significant amount of compilation time and/or
-                           are relatively new.
+                           are relatively new. Note that differs from -O2 only
+                           during the bitcode to JS (final link + JS generation)
+                           stage, as it is JS-specific, so you can run -Os
+                           on your source files for example, and -O3 during
+                           JS generation if you want.
 
                            For tips on optimizing your code, see
                            https://github.com/kripken/emscripten/wiki/Optimizing-Code
@@ -810,8 +818,13 @@ try:
       # Let -O default to -O2, which is what gcc does.
       requested_level = newargs[i][2:] or '2'
       if requested_level == 's':
+        llvm_opts = ['-Os']
         requested_level = 2
         settings_changes.append('INLINING_LIMIT=50')
+      elif requested_level == 'z':
+        llvm_opts = ['-Oz']
+        requested_level = 2
+        settings_changes.append('INLINING_LIMIT=25')
       opt_level = validate_arg_level(requested_level, 3, 'Invalid optimization level: ' + newargs[i])
       # We leave the -O option in place so that the clang front-end runs in that
       # optimization mode, but we disable the actual optimization passes, as we'll
@@ -1353,7 +1366,7 @@ try:
         file_ending = filename_type_ending(input_file)
         if file_ending.endswith(SOURCE_ENDINGS):
           temp_file = temp_files[i]
-          logging.debug('optimizing %s with -O%s', input_file, llvm_opts)
+          logging.debug('optimizing %s', input_file)
           shared.Building.llvm_opt(temp_file, llvm_opts)
 
   # If we were just asked to generate bitcode, stop there

tests/test_other.py

@@ -2428,3 +2428,20 @@ int main(int argc, char **argv) {
         assert ('_ZN5WasteILi2EED1Ev' in src) == exit, 'destructors should not appear if no exit'
         assert ('atexit(' in src) == exit, 'atexit should not appear or be called'
 
+  def test_os_oz(self):
+    if os.environ.get('EMCC_DEBUG'): return self.skip('cannot run in debug mode')
+    try:
+      os.environ['EMCC_DEBUG'] = '1'
+      for args, expect in [
+          (['-O1'], 'LLVM opts: -O1'),
+          (['-O2'], 'LLVM opts: -O3'),
+          (['-Os'], 'LLVM opts: -Os'),
+          (['-Oz'], 'LLVM opts: -Oz'),
+          (['-O3'], 'LLVM opts: -O3'),
+        ]:
+        print args, expect
+        output, err = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world.cpp')] + args, stdout=PIPE, stderr=PIPE).communicate()
+        self.assertContained(expect, err)
+    finally:
+      del os.environ['EMCC_DEBUG']
+