627341 - Wrong stack alignment in Convert_ascii_run call on mingw build.

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Jacek Caban]

Attachment: fix v1.0

Stack alignment is not guaranteed by ABI and GCC doesn't enforce it in function prolog. There is already similar problem in gfx/cairo/libpixman/src/pixman.c. It's interesting that we don't hit it on Linux GCC builds (although its ABI also doesn't enforce alignment). The attached patch fixes the problem by adding __force_align_arg_pointer__ attribute.

Comment 1

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

Comment on attachment 505397 [details] [diff] [review]
fix v1.0

Look simple enough, but I don't think I'm the right person to review this.

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

(In reply to comment #0)
> It's interesting that we don't hit it on Linux GCC builds (although its ABI
> also doesn't enforce alignment).

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38496
suggest that Linux ABI does require 16-bit stack alignment.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 505397 [details] [diff] [review]
fix v1.0

r=dbaron, but in the future, please post patches with 8 lines of context, and preferably with a useful From: header and commit message.

Comment 4

[Jacek Caban]

Sorry for the patch format, I will change that in the future.

http://hg.mozilla.org/mozilla-central/rev/fa9559ec420a