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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Rohan McLure <rmclure@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com
Subject: Re: [PATCH 1/6] powerpc: Add ZERO_GPRS macros for register clears
Date: Fri, 10 Jun 2022 09:05:48 -0500	[thread overview]
Message-ID: <20220610140548.GQ25951@gate.crashing.org> (raw)
In-Reply-To: <88BD925A-D6A8-4983-A573-7D9CEE51CDE7@linux.ibm.com>

Hi!

On Fri, Jun 10, 2022 at 01:32:58PM +1000, Rohan McLure wrote:
> > On 2 Jun 2022, at 2:00 am, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> > This is for unary operations, not binary operations (there is only one
> > item on the RHS).  You can in principle put a string "a,b" in the rhs
> > parameter, but in practice you need a or b to depend on the loop counter
> > as well, so even such trickiness won't do.  Make the naming less
> > confusing, maybe?  Or don't have an unused extra level of abstraction in
> > the first place :-)

> Yep I see how having a macro to perform rX = rX <> Y for arbitrary infix <> and operand
> is unlikely to find much use outside of ZERO_GPRS.

Aha.  On PowerPC (like on most RISC-like architectures) all the normal
instructions are rD := rA OP rB, not rD := rD OP rA.  It looks like
that is our disconnect :-)


Segher

  reply	other threads:[~2022-06-10 14:08 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-01  5:48 [PATCH 1/6] powerpc: Add ZERO_GPRS macros for register clears Rohan McLure
2022-06-01  5:48 ` [PATCH 2/6] powerpc: Provide syscall wrapper Rohan McLure
2022-06-01  8:29   ` Christophe Leroy
2022-06-09 13:06     ` Christophe Leroy
2022-06-16  5:42       ` Rohan McLure
2022-06-16  7:20         ` Arnd Bergmann
2022-06-01  8:59   ` kernel test robot
2022-06-01  9:35   ` kernel test robot
2022-06-01 12:23   ` kernel test robot
2022-06-01 14:33   ` Christophe Leroy
2022-06-03  3:24     ` Rohan McLure
2022-06-03  7:09       ` Andrew Donnellan
2022-06-03  8:39         ` Christophe Leroy
2022-06-14 13:57           ` Andrew Donnellan
2022-06-03  9:04   ` Arnd Bergmann
2022-06-15  1:47     ` Rohan McLure
2022-06-15 10:13       ` Arnd Bergmann
2022-06-01  5:48 ` [PATCH 3/6] powerpc: Make syscalls save and restore gprs Rohan McLure
2022-06-01  8:33   ` Christophe Leroy
2022-06-01  5:48 ` [PATCH 4/6] powerpc: Fix comment, use clear and restore macros Rohan McLure
2022-06-01  5:48 ` [PATCH 5/6] powerpc: Move syscall handler prototypes to header Rohan McLure
2022-06-01  5:48 ` [PATCH 6/6] powerpc/64s: Clear gprs on interrupt routine entry Rohan McLure
2022-06-01  8:37   ` Christophe Leroy
2022-06-01  7:45 ` [PATCH 1/6] powerpc: Add ZERO_GPRS macros for register clears Christophe Leroy
2022-06-01 16:00 ` Segher Boessenkool
2022-06-10  3:32   ` Rohan McLure
2022-06-10 14:05     ` Segher Boessenkool [this message]
2022-06-11  8:42     ` Christophe Leroy
2022-06-13 18:48       ` Segher Boessenkool
2022-06-14  4:31         ` Michael Ellerman
2022-06-14 11:43           ` Segher Boessenkool

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