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(distribute_notes): If can't find place for REG_DEAD note, add an INSN

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with a USE to hold it.

From-SVN: r8625
This commit is contained in:
Richard Kenner 1994-12-07 21:57:53 -05:00
parent 61314cb469
commit 38d8473fbb
1 changed files with 51 additions and 39 deletions
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90
gcc/combine.c
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@ -10515,49 +10515,50 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
reg_n_refs[REGNO (XEXP (note, 0))] = 3;
if (place == 0)
for (tem = prev_nonnote_insn (i3);
tem && (GET_CODE (tem) == INSN
|| GET_CODE (tem) == CALL_INSN);
tem = prev_nonnote_insn (tem))
{
/* If the register is being set at TEM, see if that is all
TEM is doing. If so, delete TEM. Otherwise, make this
into a REG_UNUSED note instead. */
if (reg_set_p (XEXP (note, 0), PATTERN (tem)))
{
rtx set = single_set (tem);
{
for (tem = prev_nonnote_insn (i3);
place == 0 && tem
&& (GET_CODE (tem) == INSN || GET_CODE (tem) == CALL_INSN);
tem = prev_nonnote_insn (tem))
{
/* If the register is being set at TEM, see if that is all
TEM is doing. If so, delete TEM. Otherwise, make this
into a REG_UNUSED note instead. */
if (reg_set_p (XEXP (note, 0), PATTERN (tem)))
{
rtx set = single_set (tem);
/* Verify that it was the set, and not a clobber that
modified the register. */
/* Verify that it was the set, and not a clobber that
modified the register. */
if (set != 0 && ! side_effects_p (SET_SRC (set))
&& rtx_equal_p (XEXP (note, 0), SET_DEST (set)))
{
/* Move the notes and links of TEM elsewhere.
This might delete other dead insns recursively.
First set the pattern to something that won't use
any register. */
if (set != 0 && ! side_effects_p (SET_SRC (set))
&& rtx_equal_p (XEXP (note, 0), SET_DEST (set)))
{
/* Move the notes and links of TEM elsewhere.
This might delete other dead insns recursively.
First set the pattern to something that won't use
any register. */
PATTERN (tem) = pc_rtx;
PATTERN (tem) = pc_rtx;
distribute_notes (REG_NOTES (tem), tem, tem,
NULL_RTX, NULL_RTX, NULL_RTX);
distribute_links (LOG_LINKS (tem));
distribute_notes (REG_NOTES (tem), tem, tem,
NULL_RTX, NULL_RTX, NULL_RTX);
distribute_links (LOG_LINKS (tem));
PUT_CODE (tem, NOTE);
NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (tem) = 0;
}
else
{
PUT_REG_NOTE_KIND (note, REG_UNUSED);
/* If there isn't already a REG_UNUSED note, put one
here. */
if (! find_regno_note (tem, REG_UNUSED,
REGNO (XEXP (note, 0))))
place = tem;
break;
PUT_CODE (tem, NOTE);
NOTE_LINE_NUMBER (tem) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (tem) = 0;
}
else
{
PUT_REG_NOTE_KIND (note, REG_UNUSED);
/* If there isn't already a REG_UNUSED note, put one
here. */
if (! find_regno_note (tem, REG_UNUSED,
REGNO (XEXP (note, 0))))
place = tem;
break;
}
}
else if (reg_referenced_p (XEXP (note, 0), PATTERN (tem))
@ -10567,7 +10568,18 @@ distribute_notes (notes, from_insn, i3, i2, elim_i2, elim_i1)
place = tem;
break;
}
}
}
/* If we haven't found an insn for the death note and it
is still a REG_DEAD note, but we have hit a CODE_LABEL,
insert a USE insn for the register at that label and
put the death node there. This prevents problems with
call-state tracking in caller-save.c. */
if (REG_NOTE_KIND (note) == REG_DEAD && place == 0 && tem != 0)
place
= emit_insn_after (gen_rtx (USE, VOIDmode, XEXP (note, 0)),
tem);
}
/* If the register is set or already dead at PLACE, we needn't do
anything with this note if it is still a REG_DEAD note.