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On Fri, Nov 9, 2012 at 2:28 PM, Uros Bizjak <ubizjak@gmail.com> wrote:
> Finally, having a post-reload mode-switching pass, we can double-check
> that there are no live SSE registers at vzeroupper insertion point. As
> vzeroupper is only an optimization, we want to play safe and cancel
> vzeroupper insertion in this case
>
> There is no degradation for x86_64 gABI targets, since all SSE
> registers are call-clobbered. Vzeroupper is conditionally inserted
> just before call insn, where all registers are saved to stack and
> already dead. The vzeroupper at function exit is not problematic.
Patch was committed to mainline SVN with the following ChangeLog:
2012-11-16 Uros Bizjak <ubizjak@gmail.com>
* config/i386/i386-protos.h (ix86_emit_mode_set): Add third argument.
* config/i386/i386.h (EMIT_MODE_SET): Update.
* config/i386/i386.c (ix86_avx_emit_vzeroupper): New function.
(ix86_emit_mode_set) <AVX_U128>: Call ix86_avx_emit_vzeroupper.
Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32},
configured with --with-arch=corei7-avx --with-tune=corei7-avx.
Uros.
Attachment:
p.diff.txt
Description: Text document
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