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Re: IA-64 speculation patches have bad impact on ARM
- From: Maxim Kuvyrkov <mkuvyrkov at ispras dot ru>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: Mark Mitchell <mark at codesourcery dot com>, David Edelsohn <dje at watson dot ibm dot com>, Daniel Jacobowitz <drow at false dot org>, Andrey Belevantsev <abel at ispras dot ru>, gcc at gcc dot gnu dot org
- Date: Thu, 01 Jun 2006 15:55:00 +0400
- Subject: Re: IA-64 speculation patches have bad impact on ARM
- References: <20060526160808.GA1059@nevyn.them.org> <447C61D9.firstname.lastname@example.org> <200605301520.k4UFKm731478@makai.watson.ibm.com> <447C6AE0.email@example.com> <447C730A.firstname.lastname@example.org>
Vladimir Makarov wrote:
I am agree with this. Two months ago Maxim submitted patches which
affects only ia64 except one thing affecting all targets - the patch
which builds more scheduling regions and as consequence permits more
aggressive interblock scheduling.
Insn scheduling before the register allocation even without Maxim's
patches is not safe when hard registers are used in RTL. It is a
known bug (e.g. for x86_64) and it is in bugzilla. Jim Wilson wrote
several possible solutions for this, no one is easy to implement
except for switching off insn scheduling before RA (what is done for
But we can restore the state (probably safe for most programs) what
was before Maxim's patch. So Maxim could you do this (of course you
can save max-sched-extend-regions-iters value for ia64 because it is
probably safe for targets with many registers).
Considering that bug, I agree that by default there should be no
additional regions. The patch will be posted in a few minutes.