Messages in this thread | | | Date | Tue, 28 Feb 2017 22:04:10 +0000 | From | "Maciej W. Rozycki" <> | Subject | Re: [PATCH 2/4] MIPS: microMIPS: Fix decoding of addiusp instruction |
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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?
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
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