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combine.c (distribute_notes): If an insn is a cc0 user, only delete it if we can also delete the cc0 setter.

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* combine.c (distribute_notes): If an insn is a cc0 user, only
        delete it if we can also delete the cc0 setter.

From-SVN: r22489
This commit is contained in:
Richard Henderson 1998-09-19 17:01:31 -07:00 committed by Richard Henderson
parent a58bd5080a
commit f5c9764010
2 changed files with 36 additions and 2 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Sun Sep 20 00:00:51 1998 Richard Henderson <rth@cygnus.com>
* combine.c (distribute_notes): If an insn is a cc0 user, only
delete it if we can also delete the cc0 setter.
Sun Sep 20 00:22:23 1998 Michael Tiemann <michael@impact.tiemann.org>
* fold-const.c (fold): Fix typo in COND_EXPR handling code.

33
gcc/combine.c
View File

@ -11542,6 +11542,7 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
{
rtx set = single_set (tem);
rtx inner_dest = 0;
rtx cc0_setter = NULL_RTX;
if (set != 0)
for (inner_dest = SET_DEST (set);
@ -11552,10 +11553,21 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
;
/* Verify that it was the set, and not a clobber that
modified the register. */
modified the register.
CC0 targets must be careful to maintain setter/user
pairs. If we cannot delete the setter due to side
effects, mark the user with an UNUSED note instead
of deleting it. */
if (set != 0 && ! side_effects_p (SET_SRC (set))
&& rtx_equal_p (XEXP (note, 0), inner_dest))
&& rtx_equal_p (XEXP (note, 0), inner_dest)
#ifdef HAVE_cc0
&& (! reg_mentioned_p (cc0_rtx, SET_SRC (set))
|| ((cc0_setter = prev_cc0_setter (tem)) != NULL
&& sets_cc0_p (PATTERN (cc0_setter)) > 0))
#endif
)
{
/* Move the notes and links of TEM elsewhere.
This might delete other dead insns recursively.
@ -11571,6 +11583,23 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
PUT_CODE (tem, NOTE);
NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (tem) = 0;
#ifdef HAVE_cc0
/* Delete the setter too. */
if (cc0_setter)
{
PATTERN (cc0_setter) = pc_rtx;
distribute_notes (REG_NOTES (cc0_setter),
cc0_setter, cc0_setter,
NULL_RTX, NULL_RTX, NULL_RTX);
distribute_links (LOG_LINKS (cc0_setter));
PUT_CODE (cc0_setter, NOTE);
NOTE_LINE_NUMBER (cc0_setter) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (cc0_setter) = 0;
}
#endif
}
/* If the register is both set and used here, put the
REG_DEAD note here, but place a REG_UNUSED note