This is the mail archive of the binutils@sourceware.org mailing list for the binutils project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Enable 32-bit Alignment


On Fri, Jun 29, 2007 at 03:57:01PM -0500, Menezes, Evandro wrote:
> If it's not too late in the release cycle, I'd appreciate if this patch
> enabling optimal code alignment up to 32-byte boundaries, used by GCC
> when tuning for AMD Barcelona, were applied.  It also does away with the
> special NOP sequences for AMD Opteron in 64-bit code.

In the current i386_align_code, see comment "Adjust jump offset" in
block handling 16-bit mode.  Now that larger nop sequences are
allowed, I think you should similarly adjust a branch (if used) in
32-bit mode.  Also, your code sequence for 31 byte nop padding will
not be very good.  You'll get two 15 byte nops and a single nop.
Please rethink the way you have implemented this.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]