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cse.c (cse_insn): Mostly remove first hunk of code which collapsed a computed jump into an...

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* cse.c (cse_insn): Mostly remove first hunk of code which collapsed
        a computed jump into an unconditional jump.
        In second hunk of code for collapsing computed and conditional jumps
        into unconditional jumps, reemit the jump in additional cases.

From-SVN: r41953
This commit is contained in:
Jeffrey A Law 2001-05-11 00:23:46 +00:00 committed by Jeff Law
parent f3ce87a905
commit d466c016c5
2 changed files with 20 additions and 30 deletions
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5
gcc/ChangeLog
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@ -5,6 +5,11 @@
Thu May 10 14:45:44 2001 Jeffrey A Law (law@cygnus.com)
* cse.c (cse_insn): Mostly remove first hunk of code which collapsed
a computed jump into an unconditional jump.
In second hunk of code for collapsing computed and conditional jumps
into unconditional jumps, reemit the jump in additional cases.
* jump.c (jump_optimize_1): Do not wrap the new jump target
inside a LABEL_REF; gen_jump will do that automatically.

45
gcc/cse.c
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@ -5518,31 +5518,17 @@ cse_insn (insn, libcall_insn)
check for this separately here. We will delete such an
insn below.
Tablejump insns contain a USE of the table, so simply replacing
the operand with the constant won't match. This is simply an
unconditional branch, however, and is therefore valid. Just
insert the substitution here and we will delete and re-emit
the insn later. */
For other cases such as a table jump or conditional jump
where we know the ultimate target, go ahead and replace the
operand. While that may not make a valid insn, we will
reemit the jump below (and also insert any necessary
barriers). */
if (n_sets == 1 && dest == pc_rtx
&& (trial == pc_rtx
|| (GET_CODE (trial) == LABEL_REF
&& ! condjump_p (insn))))
{
if (trial == pc_rtx)
{
SET_SRC (sets[i].rtl) = trial;
cse_jumps_altered = 1;
break;
}
PATTERN (insn) = gen_jump (XEXP (trial, 0));
INSN_CODE (insn) = -1;
if (NEXT_INSN (insn) != 0
&& GET_CODE (NEXT_INSN (insn)) != BARRIER)
emit_barrier_after (insn);
SET_SRC (sets[i].rtl) = trial;
cse_jumps_altered = 1;
break;
}
@ -5804,13 +5790,17 @@ cse_insn (insn, libcall_insn)
}
/* If this SET is now setting PC to a label, we know it used to
be a conditional or computed branch. So we see if we can follow
it. If it was a computed branch, delete it and re-emit. */
be a conditional or computed branch. */
else if (dest == pc_rtx && GET_CODE (src) == LABEL_REF)
{
/* If this is not in the format for a simple branch and
we are the only SET in it, re-emit it. */
if (! simplejump_p (insn) && n_sets == 1)
/* We reemit the jump in as many cases as possible just in
case the form of an unconditional jump is significantly
different than a computed jump or conditional jump.
If this insn has multiple sets, then reemitting the
jump is nontrivial. So instead we just force rerecognition
and hope for the best. */
if (n_sets == 1)
{
rtx new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
JUMP_LABEL (new) = XEXP (src, 0);
@ -5818,11 +5808,6 @@ cse_insn (insn, libcall_insn)
insn = new;
}
else
/* Otherwise, force rerecognition, since it probably had
a different pattern before.
This shouldn't really be necessary, since whatever
changed the source value above should have done this.
Until the right place is found, might as well do this here. */
INSN_CODE (insn) = -1;
never_reached_warning (insn);