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loop.c (check_dbra_loop): Use a vanilla loop reversal if the biv is used to compute a giv or as some...

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* loop.c (check_dbra_loop): Use a vanilla loop reversal if the biv is
        used to compute a giv or as some other non-counting use.

From-SVN: r22684
This commit is contained in:
Jeffrey A Law 1998-09-30 17:32:15 +00:00 • committed by Jeff Law
parent c1daea12d5
commit c5cbf81ecf
2 changed files with 14 additions and 3 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Wed Sep 30 18:29:26 1998 Jeffrey A Law (law@cygnus.com)
* loop.c (check_dbra_loop): Use a vanilla loop reversal if the biv is
used to compute a giv or as some other non-counting use.
Wed Sep 30 18:19:27 1998 Michael Hayes <m.hayes@elec.canterbury.ac.nz>
* regs.h (HARD_REGNO_CALLER_SAVE_MODE): New macro.

12
gcc/loop.c
View file

@ -6992,9 +6992,13 @@ check_dbra_loop (loop_end, insn_count, loop_start)
if (initial_value == const0_rtx
/* If we have a decrement_and_branch_on_count, prefer
the NE test, since this will allow that instruction to
be generated. */
be generated. Note that we must use a vanilla loop
reversal if the biv is used to calculate a giv or has
a non-counting use. */
#if ! defined (HAVE_decrement_and_branch_until_zero) && defined (HAVE_decrement_and_branch_on_count)
&& (add_val != 1 || ! vtop)
&& (! (add_val == 1 && vtop
&& (bl->biv_count == 0
|| no_use_except_counting)))
#endif
&& GET_CODE (comparison_value) == CONST_INT
/* Now do postponed overflow checks on COMPARISON_VAL. */
@ -7007,7 +7011,9 @@ check_dbra_loop (loop_end, insn_count, loop_start)
nonneg = 1;
cmp_code = GE;
}
else if (add_val == 1 && vtop)
else if (add_val == 1 && vtop
&& (bl->biv_count == 0
|| no_use_except_counting))
{
add_adjust = 0;
cmp_code = NE;