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recog.c (split_insn): Consider attaching a REG_EQUAL note to the final insn of a split.

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gcc/
	* recog.c (split_insn): Consider attaching a REG_EQUAL note to the
	final insn of a split.

From-SVN: r139802
This commit is contained in:
Richard Sandiford 2008-08-30 13:12:16 +00:00 • committed by Richard Sandiford
parent 8bcf15f6ea
commit a2a9208308
2 changed files with 25 additions and 0 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2008-08-30 Richard Sandiford <rdsandiford@googlemail.com>
* recog.c (split_insn): Consider attaching a REG_EQUAL note to the
final insn of a split.
2008-08-30 Jan Hubicka <jh@suse.cz>
* postreload-gcse.c (gate_handle_gcse2): Disable for functions

20
gcc/recog.c
View file

@ -2630,10 +2630,29 @@ split_insn (rtx insn)
/* Split insns here to get max fine-grain parallelism. */
rtx first = PREV_INSN (insn);
rtx last = try_split (PATTERN (insn), insn, 1);
rtx insn_set, last_set, note;
if (last == insn)
return NULL_RTX;
/* If the original instruction was a single set that was known to be
equivalent to a constant, see if we can say the same about the last
instruction in the split sequence. The two instructions must set
the same destination. */
insn_set = single_set (insn);
if (insn_set)
{
last_set = single_set (last);
if (last_set && rtx_equal_p (SET_DEST (last_set), SET_DEST (insn_set)))
{
note = find_reg_equal_equiv_note (insn);
if (note && CONSTANT_P (XEXP (note, 0)))
set_unique_reg_note (last, REG_EQUAL, XEXP (note, 0));
else if (CONSTANT_P (SET_SRC (insn_set)))
set_unique_reg_note (last, REG_EQUAL, SET_SRC (insn_set));
}
}
/* try_split returns the NOTE that INSN became. */
SET_INSN_DELETED (insn);
@ -2651,6 +2670,7 @@ split_insn (rtx insn)
first = NEXT_INSN (first);
}
}
return last;
}