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(check_dbra_loop): When reversing loop when 

no_use_except_counting is false, there must be only one biv.

From-SVN: r9642
This commit is contained in:
Jim Wilson 1995-05-12 08:16:31 -07:00
parent a193a6db03
commit 45cc060eb5
1 changed files with 8 additions and 2 deletions
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10
gcc/loop.c
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@ -5724,6 +5724,11 @@ check_dbra_loop (loop_end, insn_count, loop_start)
all memory references have non-overlapping addresses
(obviously true if only one write)
allow 2 insns for the compare/jump at the end of the loop. */
/* Also, we must avoid any instructions which use both the reversed
biv and another biv. Such instructions will fail if the loop is
reversed. We meet this condition by requiring that either
no_use_except_counting is true, or else that there is only
one biv. */
int num_nonfixed_reads = 0;
/* 1 if the iteration var is used only to count iterations. */
int no_use_except_counting = 0;
@ -5788,8 +5793,9 @@ check_dbra_loop (loop_end, insn_count, loop_start)
&& !loop_has_volatile
&& reversible_mem_store
&& (no_use_except_counting
|| (bl->giv_count + bl->biv_count + num_mem_sets
+ num_movables + 2 == insn_count)))
|| ((bl->giv_count + bl->biv_count + num_mem_sets
+ num_movables + 2 == insn_count)
&& (bl == loop_iv_list && bl->next == 0))))
{
rtx tem;