Hi Maciej,
On 28/02/17 22:04, Maciej W. Rozycki wrote:
On Tue, 28 Feb 2017, Matt Redfearn wrote:
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 5b1e932ae973..6ba5b775579c 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -386,8 +386,9 @@ static int get_frame_info(struct mips_frame_info *info)
if (ip->halfword[0] & mm_addiusp_func)
{
- tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
- info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
+ tmp = (ip->halfword[0] >> 1) & 0x1ff;
+ tmp = tmp | ((tmp & 0x100) ? 0xfe00 : 0);
+ info->frame_size = -(signed short)(tmp << 2);
Ugh, this is unreadable -- can you please figure out a way to fit it in
79 columns? Perhaps by factoring this piece out?
Yeah, it's not pretty. I've got a v2 which refactors this into
is_sp_move_ins, which makes it work the same way as is_ra_save_ins and
perform the immediate interpretation there, instead.
But I've kept that as a separate patch so as to keep the functional fix
and refactor separate.
Also this:
tmp = (ip->halfword[0] >> 1) & 0x1ff;
tmp = tmp | ((tmp & 0x100) ? 0xfe00 : 0);
will likely result in better code without the conditional, e.g.:
tmp = (((ip->halfword[0] >> 1) & 0x1ff) ^ 0x100) - 0x100;
(the usual way to sign-extend).
Maciej
Yes, that looks nicer.
Thanks,
Matt
