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ifcvt.c (merge_if_block): Be prepared for JOIN to have no remaining edges.

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* ifcvt.c (merge_if_block): Be prepared for JOIN to have no
        remaining edges.
        (find_if_block): Allow THEN with no outgoing edges.
        * flow.c (merge_blocks_nomove): Remove a barrier not following
        a jump as well.

From-SVN: r34317
This commit is contained in:
Richard Henderson 2000-05-31 17:03:36 -07:00 committed by Richard Henderson
parent e0fa93b3ca
commit 18153f6ceb
2 changed files with 26 additions and 7 deletions
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3
gcc/ChangeLog
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@ -4,6 +4,9 @@
2000-05-31 Richard Henderson <rth@cygnus.com>
* ifcvt.c (merge_if_block): Be prepared for JOIN to have no
remaining edges.
(find_if_block): Allow THEN with no outgoing edges.
* flow.c (merge_blocks_nomove): Remove a barrier not following
a jump as well.

30
gcc/ifcvt.c
View File

@ -1356,8 +1356,10 @@ merge_if_block (test_bb, then_bb, else_bb, join_bb)
/* The JOIN block may have had quite a number of other predecessors too.
Since we've already merged the TEST, THEN and ELSE blocks, we should
have only one remaining edge from our if-then-else diamond. If there
is more than one remaining edge, it must come from elsewhere. */
else if (join_bb->pred->pred_next == NULL)
is more than one remaining edge, it must come from elsewhere. There
may be zero incoming edges if the THEN block didn't actually join
back up (as with a call to abort). */
else if (join_bb->pred == NULL || join_bb->pred->pred_next == NULL)
{
/* We can merge the JOIN. */
if (combo_bb->global_live_at_end)
@ -1459,15 +1461,29 @@ find_if_block (test_bb, then_edge, else_edge)
if (then_bb->pred->pred_next != NULL_EDGE)
return FALSE;
/* The THEN block of an IF-THEN combo must have exactly one successor. */
if (then_succ == NULL_EDGE
|| then_succ->succ_next != NULL_EDGE
|| (then_succ->flags & EDGE_COMPLEX))
/* The THEN block of an IF-THEN combo must have zero or one successors. */
if (then_succ != NULL_EDGE
&& (then_succ->succ_next != NULL_EDGE
|| (then_succ->flags & EDGE_COMPLEX)))
return FALSE;
/* If the THEN block has no successors, conditional execution can still
make a conditional call. Don't do this unless the ELSE block has
only one incoming edge -- the CFG manipulation is too ugly otherwise. */
if (then_succ == NULL)
{
if (else_bb->pred->pred_next == NULL_EDGE)
{
join_bb = else_bb;
else_bb = NULL_BLOCK;
}
else
return FALSE;
}
/* If the THEN block's successor is the other edge out of the TEST block,
then we have an IF-THEN combo without an ELSE. */
if (then_succ->dest == else_bb)
else if (then_succ->dest == else_bb)
{
join_bb = else_bb;
else_bb = NULL_BLOCK;