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Modifying Insns
- From: Ranjit Singh <ranjit_singh_007 at yahoo dot com>
- To: gcc at gcc dot gnu dot org
- Date: Sun, 6 Oct 2002 00:12:04 -0700 (PDT)
- Subject: Modifying Insns
Hi,
GCC's optimization passes operate on rtx's
and alter it.I am trying to figure out if
there is a standard way to alter rtx
in an insn so that after substitution it
is valid.
It seems functions to do the job are
1. validate_update_rtx.
2. validate_replace_rtx_subexp.
3. validate_replace_rtx_group.
....
(all in gcc/recog.c)
Have I got it correct?
It would be nice if someone can enunciate
any obvious issues, when doing things like
1. changing reg to mem,
2. or replacing a reg by another expression.
involving regs, ... ).
and semantics of when we
should use validate_replace_rtx_group ?
I am trying to figure in the code, but it
would be great if someone could help.
Thanks and Regards,
Ranjit.
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