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re PR middle-end/52756 (255.vortex in SPEC CPU 2000 failed to build)

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2012-04-02  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52756
	* tree-ssa-threadupdate.c (def_split_header_continue_p): New function.
	(thread_through_loop_header): After threading through the loop latch
	remove the split part from the loop and clear further threading
	opportunities that would create a multiple entry loop.

	* gcc.dg/torture/pr52756.c: New testcase.

From-SVN: r186085
This commit is contained in:
Richard Guenther 2012-04-02 15:13:45 +00:00 • committed by Richard Biener
parent 64f07b6642
commit 18ce81710c
4 changed files with 68 additions and 0 deletions
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8
gcc/ChangeLog
View file

@ -1,3 +1,11 @@
2012-04-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/52756
* tree-ssa-threadupdate.c (def_split_header_continue_p): New function.
(thread_through_loop_header): After threading through the loop latch
remove the split part from the loop and clear further threading
opportunities that would create a multiple entry loop.
2012-04-02 Richard Guenther <rguenther@suse.de>
PR rtl-optimization/52800

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2012-04-02 Richard Guenther <rguenther@suse.de>
PR tree-optimization/52756
* gcc.dg/torture/pr52756.c: New testcase.
2012-04-02 Richard Guenther <rguenther@suse.de>
PR middle-end/52803

9
gcc/testsuite/gcc.dg/torture/pr52756.c Normal file
View file

@ -0,0 +1,9 @@
/* { dg-do compile } */
void Env_FetchObj0AttrOffset (unsigned int NumFields, int *Status)
{
int Found = 0;
if (NumFields)
while ((*Status == 0) && NumFields-- > 0 && Found == 0)
Found = 1;
}

46
gcc/tree-ssa-threadupdate.c
View file

@ -826,6 +826,17 @@ determine_bb_domination_status (struct loop *loop, basic_block bb)
return (bb_reachable ? DOMST_DOMINATING : DOMST_LOOP_BROKEN);
}
/* Return true if BB is part of the new pre-header that is created
when threading the latch to DATA. */
static bool
def_split_header_continue_p (const_basic_block bb, const void *data)
{
const_basic_block new_header = (const_basic_block) data;
return (bb->loop_father == new_header->loop_father
&& bb != new_header);
}
/* Thread jumps through the header of LOOP. Returns true if cfg changes.
If MAY_PEEL_LOOP_HEADERS is false, we avoid threading from entry edges
to the inside of the loop. */
@ -990,11 +1001,46 @@ thread_through_loop_header (struct loop *loop, bool may_peel_loop_headers)
if (latch->aux)
{
basic_block *bblocks;
unsigned nblocks, i;
/* First handle the case latch edge is redirected. */
loop->latch = thread_single_edge (latch);
gcc_assert (single_succ (loop->latch) == tgt_bb);
loop->header = tgt_bb;
/* Remove the new pre-header blocks from our loop. */
bblocks = XCNEWVEC (basic_block, loop->num_nodes);
nblocks = dfs_enumerate_from (header, 0, def_split_header_continue_p,
bblocks, loop->num_nodes, tgt_bb);
for (i = 0; i < nblocks; i++)
{
remove_bb_from_loops (bblocks[i]);
add_bb_to_loop (bblocks[i], loop_outer (loop));
}
free (bblocks);
/* Cancel remaining threading requests that would make the
loop a multiple entry loop. */
FOR_EACH_EDGE (e, ei, header->preds)
{
edge e2;
if (e->aux == NULL)
continue;
if (THREAD_TARGET2 (e))
e2 = THREAD_TARGET2 (e);
else
e2 = THREAD_TARGET (e);
if (e->src->loop_father != e2->dest->loop_father
&& e2->dest != loop->header)
{
free (e->aux);
e->aux = NULL;
}
}
/* Thread the remaining edges through the former header. */
thread_block (header, false);
}