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Re: VAX backend status

From: Paolo Bonzini <paolo dot bonzini at lu dot unisi dot ch>
To: Matt Thomas <matt at 3am-software dot com>
Cc: gcc at gcc dot gnu dot org
Date: Thu, 05 Apr 2007 08:38:26 +0200
Subject: Re: VAX backend status
References: <F20AA8D7-1677-4E80-8A60-4504E03800FA@3am-software.com>
Reply-to: bonzini at gnu dot org

I've noticed a few things in doing the above.  GCC 4.x doesn't seems to
do CSE on addresses.  Because the VAX binutils doesn't support non-local
symbols with a non-zero addend in the GOT, PIC will do a define_expand
so that (const (plus (symbol_ref) (const_int))) will be split into
separate instructions.  However, gcc doesn't seem to be able to take
advantage of that.  For instance, gcc emits:


File a PR, CC me and ping me when your patches are in.  I
can take a look and see whether it's the responsibility of
the VAX backend to provide more correct costs, or whether
fwprop could do something it's not doing.

Paolo

References:
- VAX backend status
  - From: Matt Thomas

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