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[parloops] Handle canonicalize_loop_ivs failure

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2018-03-21  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/83126
	* tree-parloops.c (num_phis): New function.
	(gen_parallel_loop): Detect and handle canonicalize_loop_ivs failure.

	* gcc.dg/graphite/pr83126.c: New test.

From-SVN: r258713
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Tom de Vries 2018-03-21 12:25:03 +00:00 • committed by Tom de Vries
parent f82ece6b59
commit c75c35e0f5
4 changed files with 69 additions and 0 deletions
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6
gcc/ChangeLog
View file

@ -1,3 +1,9 @@
2018-03-21 Tom de Vries <tom@codesourcery.com>
PR tree-optimization/83126
* tree-parloops.c (num_phis): New function.
(gen_parallel_loop): Detect and handle canonicalize_loop_ivs failure.
2018-03-21 Nathan Sidwell <nathan@acm.org>
* doc/extend.texi (Deprecated Features): Update deprecared flags,

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2018-03-21 Tom de Vries <tom@codesourcery.com>
PR tree-optimization/83126
* gcc.dg/graphite/pr83126.c: New test.
2018-03-21 Nathan Sidwell <nathan@acm.org>
* g++.dg/ext/anon-struct6.C: Adjust.

19
gcc/testsuite/gcc.dg/graphite/pr83126.c Normal file
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@ -0,0 +1,19 @@
/* { dg-additional-options "-w -ftree-parallelize-loops=2 -floop-parallelize-all -O1" } */
void
ew (unsigned short int c9, int stuff)
{
int e1;
for (;;)
{
unsigned int *by = &e1;
int *fd = &stuff;
*fd = c9;
fd = *fd;
if (*fd != 0)
for (*by = 0; *by < 2; ++*by)
c9 *= e1;
}
}

39
gcc/tree-parloops.c
View file

@ -2235,6 +2235,25 @@ create_parallel_loop (struct loop *loop, tree loop_fn, tree data,
calculate_dominance_info (CDI_DOMINATORS);
}
/* Return number of phis in bb. If COUNT_VIRTUAL_P is false, don't count the
virtual phi. */
static unsigned int
num_phis (basic_block bb, bool count_virtual_p)
{
unsigned int nr_phis = 0;
gphi_iterator gsi;
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
if (!count_virtual_p && virtual_operand_p (PHI_RESULT (gsi.phi ())))
continue;
nr_phis++;
}
return nr_phis;
}
/* Generates code to execute the iterations of LOOP in N_THREADS
threads in parallel, which can be 0 if that number is to be determined
later.
@ -2370,6 +2389,26 @@ gen_parallel_loop (struct loop *loop,
/* Base all the induction variables in LOOP on a single control one. */
canonicalize_loop_ivs (loop, &nit, true);
if (num_phis (loop->header, false) != reduction_list->elements () + 1)
{
/* The call to canonicalize_loop_ivs above failed to "base all the
induction variables in LOOP on a single control one". Do damage
control. */
basic_block preheader = loop_preheader_edge (loop)->src;
basic_block cond_bb = single_pred (preheader);
gcond *cond = as_a <gcond *> (gsi_stmt (gsi_last_bb (cond_bb)));
gimple_cond_make_true (cond);
update_stmt (cond);
/* We've gotten rid of the duplicate loop created by loop_version, but
we can't undo whatever canonicalize_loop_ivs has done.
TODO: Fix this properly by ensuring that the call to
canonicalize_loop_ivs succeeds. */
if (dump_file
&& (dump_flags & TDF_DETAILS))
fprintf (dump_file, "canonicalize_loop_ivs failed for loop %d,"
" aborting transformation\n", loop->num);
return;
}
/* Ensure that the exit condition is the first statement in the loop.
The common case is that latch of the loop is empty (apart from the