Misaligned .bss section for PE?

[Zuxy Meng]

"Zuxy Meng" <zuxy.meng@gmail.com> 写å
¥æ¶ˆæ¯æ–°é—»:g13f6l$t70$1@ger.gmane.org...
> Hi there,
>
> Recently I met a crash on MinGW32 caused by misaligned access of SSE 
> instructions. The root cause was that a static var wasn't aligned to a 
> 16-byte boundary. However, in gcc source this var had already been marked 
> with "__attribute__((aligned(16)))".
>
> I then checked the output of "gcc -S" and it turned out that with PE you 
> couldn't specify a symbol's alignment. Rather, the alignment was ensured 
> by explicit padding. But gcc seemed to do it right, at least within a 
> compilation unit. Unfortunately, after hundreds of objects got linked 
> together, some symbols' alignment was broken.
>
> I'm just wondering if I should report it as a GCC bug or a binutils one. 
> Any help? Thanks!


I guess I've figured it out; the object compiled with an older version of 
"as" has an alignment of 2**4, while with the new "as" has 2**2. The source 
if simple (just one line of "float var[512] __attribute__((aligned(16)));" 
The new version is

C:\MSYS\source>as --version
GNU assembler (GNU Binutils) 2.18.50.20080109
Copyright 2007 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `i686-pc-mingw32'.

-- 
Zuxy