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Delete a superfluous and buggy optimization

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From-SVN: r31670
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Bernd Schmidt 2000-01-28 18:00:04 +00:00 • committed by Bernd Schmidt
parent b9ff481444
commit 52bea68432
2 changed files with 5 additions and 119 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2000-01-28 Bernd Schmidt <bernds@cygnus.co.uk>
* jump.c (jump_optimize_1): Delete an optimization that is also done
by merge_blocks in flow.
2000-01-28 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* diagnostic.c (build_message_string, output_printf,

119
gcc/jump.c
View file

@ -1995,125 +1995,6 @@ jump_optimize_1 (f, cross_jump, noop_moves, after_regscan, mark_labels_only)
#endif
else
{
/* Look for if (foo) bar; else break; */
/* The insns look like this:
insn = condjump label1;
...range1 (some insns)...
jump label2;
label1:
...range2 (some insns)...
jump somewhere unconditionally
label2: */
{
rtx label1 = next_label (insn);
rtx range1end = label1 ? prev_active_insn (label1) : 0;
/* Don't do this optimization on the first round, so that
jump-around-a-jump gets simplified before we ask here
whether a jump is unconditional.
Also don't do it when we are called after reload since
it will confuse reorg. */
if (! first
&& (reload_completed ? ! flag_delayed_branch : 1)
/* Make sure INSN is something we can invert. */
&& condjump_p (insn)
&& label1 != 0
&& JUMP_LABEL (insn) == label1
&& LABEL_NUSES (label1) == 1
&& GET_CODE (range1end) == JUMP_INSN
&& simplejump_p (range1end))
{
rtx label2 = next_label (label1);
rtx range2end = label2 ? prev_active_insn (label2) : 0;
if (range1end != range2end
&& JUMP_LABEL (range1end) == label2
&& GET_CODE (range2end) == JUMP_INSN
&& GET_CODE (NEXT_INSN (range2end)) == BARRIER
/* Invert the jump condition, so we
still execute the same insns in each case. */
&& invert_jump (insn, label1))
{
rtx range1beg = next_active_insn (insn);
rtx range2beg = next_active_insn (label1);
rtx range1after, range2after;
rtx range1before, range2before;
rtx rangenext;
/* Include in each range any notes before it, to be
sure that we get the line number note if any, even
if there are other notes here. */
while (PREV_INSN (range1beg)
&& GET_CODE (PREV_INSN (range1beg)) == NOTE)
range1beg = PREV_INSN (range1beg);
while (PREV_INSN (range2beg)
&& GET_CODE (PREV_INSN (range2beg)) == NOTE)
range2beg = PREV_INSN (range2beg);
/* Don't move NOTEs for blocks or loops; shift them
outside the ranges, where they'll stay put. */
range1beg = squeeze_notes (range1beg, range1end);
range2beg = squeeze_notes (range2beg, range2end);
/* Get current surrounds of the 2 ranges. */
range1before = PREV_INSN (range1beg);
range2before = PREV_INSN (range2beg);
range1after = NEXT_INSN (range1end);
range2after = NEXT_INSN (range2end);
/* Splice range2 where range1 was. */
NEXT_INSN (range1before) = range2beg;
PREV_INSN (range2beg) = range1before;
NEXT_INSN (range2end) = range1after;
PREV_INSN (range1after) = range2end;
/* Splice range1 where range2 was. */
NEXT_INSN (range2before) = range1beg;
PREV_INSN (range1beg) = range2before;
NEXT_INSN (range1end) = range2after;
PREV_INSN (range2after) = range1end;
/* Check for loop notes between the end of
range2, and the next code label. If there is one,
then what we have really seen is
if (foo) break; end_of_loop;
and moved the break sequence outside the loop.
We must move LOOP_END, LOOP_VTOP and LOOP_CONT
notes (in order) to where the loop really ends now,
or we will confuse loop optimization. Stop if we
find a LOOP_BEG note first, since we don't want to
move the notes in that case. */
for (;range2after != label2; range2after = rangenext)
{
rangenext = NEXT_INSN (range2after);
if (GET_CODE (range2after) == NOTE)
{
int kind = NOTE_LINE_NUMBER (range2after);
if (kind == NOTE_INSN_LOOP_END
|| kind == NOTE_INSN_LOOP_VTOP
|| kind == NOTE_INSN_LOOP_CONT)
{
NEXT_INSN (PREV_INSN (range2after))
= rangenext;
PREV_INSN (rangenext)
= PREV_INSN (range2after);
PREV_INSN (range2after)
= PREV_INSN (range1beg);
NEXT_INSN (range2after) = range1beg;
NEXT_INSN (PREV_INSN (range1beg))
= range2after;
PREV_INSN (range1beg) = range2after;
}
else if (NOTE_LINE_NUMBER (range2after)
== NOTE_INSN_LOOP_BEG)
break;
}
}
changed = 1;
continue;
}
}
}
/* Now that the jump has been tensioned,
try cross jumping: check for identical code
before the jump and before its target label. */