This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: birthpoints in rtl.
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: Kenneth Zadeck <zadeck at naturalbridge dot com>
- Cc: Steven Bosscher <stevenb dot gcc at gmail dot com>, Jan Hubicka <hubicka at ucw dot cz>, Diego Novillo <dnovillo at google dot com>, 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>, rsandifo at nildram dot co dot uk
- Date: Sat, 08 Mar 2008 16:19:19 -0300
- Subject: Re: birthpoints in rtl.
- References: <47C5EF2A.5020401@naturalbridge.com> <47C6B132.3090903@naturalbridge.com> <47C88C6B.8030809@google.com> <571f6b510802291604t6ba0d302uc1a6bda69a7f807@mail.gmail.com> <47C89EC3.7030109@google.com> <47C8B3BB.4000801@naturalbridge.com> <20080301101315.GB24550@atrey.karlin.mff.cuni.cz> <571f6b510803041108i3fa5aa7fw61bccb913a996b03@mail.gmail.com> <87fxv6l19d.fsf@firetop.home> <47CDA92A.40008@naturalbridge.com>
On Mar 4, 2008, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:
> Richard Sandiford wrote:
>> If we went for an explicit move, I assume we would either have to
>> (a) discount hard regs that can't be moved, (b) force backends to
>> allow all no-op moves or (c) circumvent the backend somehow.
> From my point of view, this is a killer argument that if we want to
> build fuds/birthpoints for all regs, the info must be on the side.
Nah. It can't be too hard to implicitly insert a
(set (match_operand 0 "anything_goes_p" "X") (match_dup 0))
pattern in every back end, even behind the scenes.
We might as well do this for USEs, CLOBBERs, ASMs (and DEBUG_INSNs),
and phase out some of the special treatment they get at various places
for not being recognizable.
--
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}