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loop.c (loop_givs_reduce): Avoid miscompilation of loops entered at bottom.

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2004-06-16  Dale Johannesen  <dalej@apple.com>

        * loop.c (loop_givs_reduce): Avoid miscompilation of
        loops entered at bottom.

From-SVN: r83248
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Dale Johannesen 2004-06-16 17:13:34 +00:00 • committed by Dale Johannesen
parent e370de6e30
commit d85428e234
2 changed files with 17 additions and 1 deletions
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gcc/ChangeLog
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@ -1,3 +1,8 @@
2004-06-16 Dale Johannesen <dalej@apple.com>
* loop.c (loop_givs_reduce): Avoid miscompilation of
loops entered at bottom.
2004-06-16 J"orn Rennecke <joern.rennecke@superh.com>
* cfglayout.c (fixup_reorder_chain): Handle case where the

13
gcc/loop.c
View file

@ -4699,13 +4699,24 @@ loop_givs_reduce (struct loop *loop, struct iv_class *bl)
this is an address giv, then try to put the increment
immediately after its use, so that flow can create an
auto-increment addressing mode. */
/* Don't do this for loops entered at the bottom, to avoid
this invalid transformation:
jmp L; -> jmp L;
TOP: TOP:
use giv use giv
L: inc giv
inc biv L:
test biv test giv
cbr TOP cbr TOP
*/
if (v->giv_type == DEST_ADDR && bl->biv_count == 1
&& bl->biv->always_executed && ! bl->biv->maybe_multiple
/* We don't handle reversed biv's because bl->biv->insn
does not have a valid INSN_LUID. */
&& ! bl->reversed
&& v->always_executed && ! v->maybe_multiple
&& INSN_UID (v->insn) < max_uid_for_loop)
&& INSN_UID (v->insn) < max_uid_for_loop
&& !loop->top)
{
/* If other giv's have been combined with this one, then
this will work only if all uses of the other giv's occur