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Re: [PATCH], PR target/87033, General LWAX on PowerPC


On Mon, Aug 20, 2018 at 06:45:37PM -0400, Michael Meissner wrote:
> In this patch earlier to improve switch behavior:
> https://gcc.gnu.org/ml/gcc-patches/2018-07/msg01957.html
> 
> I noticed that the compiler wasn't generating the LWAX instruction.  I tracked
> this down to the "extendsi<mode>2" insn using the "Y" constraint when it can
> optimize a load + sign extend into a single load with sign extend.  The "Y"
> constraint is for DS-form offsettable addresses, and does not allow indexed
> addresses (i.e. X-form loads).  This patch adds the "Z" constraint as well,
> which allows indexed addresses.

This is okay for trunk, and for backports too.  Thanks!


> +/* { dg-do compile { target { powerpc*-*-* && lp64 } } } */

Maybe add a comment on why lp64 is needed here, it took me a minute :-)


Segher


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