From: Segher Boessenkool <segher@kernel.crashing.org>
To: Matt Brown <matthew.brown.dev@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v3 4/5] powerpc/lib/sstep: Add prty instruction emulation
Date: Tue, 25 Jul 2017 10:30:33 -0500 [thread overview]
Message-ID: <20170725153033.GH13471@gate.crashing.org> (raw)
In-Reply-To: <20170725033320.17893-4-matthew.brown.dev@gmail.com>
On Tue, Jul 25, 2017 at 01:33:19PM +1000, Matt Brown wrote:
> +static nokprobe_inline void do_prty(struct pt_regs *regs, unsigned long v,
> + int size, int ra)
> +{
> + unsigned long long res = v;
> +
> + res = (0x0001000100010001 & res) + (0x0001000100010001 & (res >> 8));
> + res = (0x0000000700000007 & res) + (0x0000000700000007 & (res >> 16));
> + if (size == 32) { /* prtyw */
> + regs->gpr[ra] = (0x0000000100000001 & res);
> + return;
> + }
> +
> + res = (0x000000000000000f & res) + (0x000000000000000f & (res >> 32));
> + regs->gpr[ra] = res & 1; /*prtyd */
> +}
Does 7's and 0xf look strange (since the top bit in the values there
is always 0). You always "and" the values with 1 later, you could do
that immediately (and change + to ^).
A general question about these patches: some things are inside #ifdef
__powerpc64__, some are not. It seems it is the wrong macro, and it
should be used (or not used) consistently?
Segher
next prev parent reply other threads:[~2017-07-25 15:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-25 3:33 [PATCH v3 1/5] powerpc/lib/sstep: Add cmpb instruction emulation Matt Brown
2017-07-25 3:33 ` [PATCH v3 2/5] powerpc/lib/sstep: Add popcnt " Matt Brown
2017-07-25 7:12 ` Balbir Singh
2017-07-25 10:24 ` David Laight
2017-07-25 13:32 ` Balbir Singh
2017-07-26 7:29 ` Gabriel Paubert
2017-07-25 3:33 ` [PATCH v3 3/5] powerpc/lib/sstep: Add bpermd " Matt Brown
2017-07-25 3:33 ` [PATCH v3 4/5] powerpc/lib/sstep: Add prty " Matt Brown
2017-07-25 8:08 ` Balbir Singh
2017-07-26 7:49 ` Gabriel Paubert
2017-07-25 15:30 ` Segher Boessenkool [this message]
2017-07-26 10:03 ` Michael Ellerman
2017-07-26 16:02 ` Segher Boessenkool
2017-07-27 1:26 ` Michael Ellerman
2017-07-28 0:48 ` Matt Brown
2017-07-28 1:31 ` Michael Ellerman
2017-07-25 3:33 ` [PATCH v3 5/5] powerpc/lib/sstep: Add isel " Matt Brown
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