Expose LLC's -force-align-stack flag to pnacl-translate

tests/toolchain/stackalign_test.c

+/*
+ * Copyright (c) 2011 The Native Client Authors. All rights reserved.

[Mark Seaborn, 2014/08/28 19:13:14]

Nit: 2014

[Derek Schuff, 2014/08/28 22:07:24]

Done.

+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+void call_with_misaligned_stack(void (*func)());

[Mark Seaborn, 2014/08/28 19:13:13]

"()" -> "(void)"

This is supposed to be getting compiled with -Wstrict-prototypes.

Apparently -Wstrict-prototypes is broken in Clang.

[Derek Schuff, 2014/08/28 22:07:24]

Done.

[Nico, 2014/08/29 04:34:09]

If you find warnings that don't work right in clang, please file a bug at
http://llvm.org/bugs and send me a link to it. (Or just send me an email, if you
don't want to create a llvm bugzilla account.) We might be able to fix things.

+
+volatile uintptr_t addrf;
+
+/*
+   Test that locals are properly aligned, even if functions are called with a

[Mark Seaborn, 2014/08/28 19:13:13]

Use NaCl comment style

[Derek Schuff, 2014/08/28 22:07:24]

Done.

+   misaligned stack. This tests the effect of LLC's -force-align-stack (and also
+   the fact that doubles must be 8-byte aligned). This test should only pass
+   when using a flag that forces stack realignment.
+*/
+void testfunc() {

[Mark Seaborn, 2014/08/28 19:13:13]

"(void)"

[Derek Schuff, 2014/08/28 22:07:24]

Done.

+  double f;
+  /* Smart compiler will optimize away the test (it assumes the alignment is

[Mark Seaborn, 2014/08/28 19:13:14]

Nit: Use the NaCl style for multiline comments, with "/*" and "*/" on separate
lines

[Derek Schuff, 2014/08/28 22:07:24]

Done.

+     correct) unless we write it to a volatile. */
+  addrf = (uintptr_t) &f;
+  if(addrf % 8 != 0) abort();

[Mark Seaborn, 2014/08/28 19:13:13]

Add space after "if", or better, use ASSERT_EQ(addrf % 8, 0) (and #include
nacl_assert.h)

[Derek Schuff, 2014/08/28 22:07:24]

Done.

+}
+
+int main() {

[Mark Seaborn, 2014/08/28 19:13:13]

"(void)"

[Derek Schuff, 2014/08/28 22:07:24]

Done.

+  printf("Calling testfunc with properly aligned stack\n");
+  testfunc();
+  printf("Calling testfunc with misaligned stack\n");
+  call_with_misaligned_stack(testfunc);
+}

[Mark Seaborn, 2014/08/28 19:13:13]

Add "return 0", otherwise the return value in undefined in C.

[Derek Schuff, 2014/08/28 22:07:24]

Done.