From: David Edelsohn <dje.gcc@gmail.com>
To: Bill Schmidt <wschmidt@linux.vnet.ibm.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH, rs6000] (2/3) Fix widening multiply high/low operations for little endian
Date: Mon, 04 Nov 2013 19:44:00 -0000 [thread overview]
Message-ID: <CAGWvny=E8rgEnM9iMhid1t3w2xY+cgGLG7Dm0=1mHEX4as5C-Q@mail.gmail.com> (raw)
In-Reply-To: <1383543252.6275.305.camel@gnopaine>
On Mon, Nov 4, 2013 at 12:34 AM, Bill Schmidt
<wschmidt@linux.vnet.ibm.com> wrote:
> Hi,
>
> This patch fixes the widening multiply high/low operations to work
> correctly in the presence of the first patch of this series, which
> reverses the meanings of multiply even/odd instructions. Here we
> reorder the input operands to the vector merge low/high instructions.
>
> The general rule is that vmrghh(x,y) [BE] = vmrglh(y,x) [LE], and so on;
> that is, we need to reverse the usage of merge high and merge low, and
> also swap their inputs, to obtain the same semantics. In this case we
> are only swapping the inputs, because the reversed usage of high and low
> has already been done for us in the generic handling code for
> VEC_WIDEN_MULT_LO_EXPR.
>
> Bootstrapped and tested with the rest of the patch set on
> powerpc64{,le}-unknown-linux-gnu, with no regressions. Is this ok for
> trunk?
>
> Thanks,
> Bill
>
>
> 2013-11-03 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
>
> * config/rs6000/altivec.md (vec_widen_umult_hi_v16qi): Swap
> arguments to merge instruction for little endian.
> (vec_widen_umult_lo_v16qi): Likewise.
> (vec_widen_smult_hi_v16qi): Likewise.
> (vec_widen_smult_lo_v16qi): Likewise.
> (vec_widen_umult_hi_v8hi): Likewise.
> (vec_widen_umult_lo_v8hi): Likewise.
> (vec_widen_smult_hi_v8hi): Likewise.
> (vec_widen_smult_lo_v8hi): Likewise.
This patch is okay.
I agree with Richard's suggestion to address the other parts of the
patch by restructuring the patterns.
Thanks, David
prev parent reply other threads:[~2013-11-04 19:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-04 5:34 Bill Schmidt
2013-11-04 18:05 ` Bill Schmidt
2013-11-04 19:44 ` David Edelsohn [this message]
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