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Re: birthpoints in rtl.
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: Kenneth Zadeck <zadeck at naturalbridge dot com>
- Cc: gcc <gcc at gcc dot gnu dot org>, "Bonzini\, Paolo" <bonzini at gnu dot org>, "Park\, Seongbae" <seongbae dot park at gmail dot com>, Ian Lance Taylor <iant at google dot com>, Richard Sandiford <rsandifo at nildram dot co dot uk>, Steven Bosscher <stevenb dot gcc at gmail dot com>
- Date: Thu, 28 Feb 2008 01:08:52 -0300
- Subject: Re: birthpoints in rtl.
- References: <47C5EF2A.5020401@naturalbridge.com>
On Feb 27, 2008, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:
> The appeal for birthpoints is that unlike the abortive attempt in
> the past to add SSA to RTL, adding a noop moves does not really mess
> up anything.
IIRC, when people tried to do RTL SSA, the problem was with match_dups
in IN/OUT operands.
I think there's a relatively simple way to deal with this: an RTL form
that takes two operands, one for input, one for output, that would
represent the SSA names for input and output that must be coalesced to
the same variable when going out of SSA, say, during register
allocation.
Has something like this been considered before?
--
Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member http://www.fsfla.org/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}