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re PR tree-optimization/87263 (ICE on valid code at -O1: verify_ssa failed)

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2018-09-13  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/87263
	* tree-ssa-sccvn.c (visit_phi): Revert some earlier changes.
	(struct unwind_state): Add max_rpo field.
	(do_rpo_vn): Allow up-to-date loop state to be used when not iterating.
	Compute max_rpo, the max RPO number a block can be backwards reached
	from.  Re-write non-iterating mode to a RPO ordered worklist approach,
	separating it from the iterating mode.

	* gcc.dg/torture/pr87263.c: New testcase.
	* gcc.dg/torture/ssa-fre-2.c: Likewise.
	* gcc.dg/torture/ssa-fre-3.c: Likewise.
	* gcc.dg/torture/ssa-fre-4.c: Likewise.

From-SVN: r264273
This commit is contained in:
Richard Biener 2018-09-13 14:15:41 +00:00 committed by Richard Biener
parent 08233f0d6e
commit 85bc75f87b
7 changed files with 266 additions and 116 deletions
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10
gcc/ChangeLog
View File

@ -1,3 +1,13 @@
2018-09-13 Richard Biener <rguenther@suse.de>
PR tree-optimization/87263
* tree-ssa-sccvn.c (visit_phi): Revert some earlier changes.
(struct unwind_state): Add max_rpo field.
(do_rpo_vn): Allow up-to-date loop state to be used when not iterating.
Compute max_rpo, the max RPO number a block can be backwards reached
from. Re-write non-iterating mode to a RPO ordered worklist approach,
separating it from the iterating mode.
2018-09-13 Vlad Lazar <vlad.lazar@arm.com>
* haifa-sched.c (rank_for_schedule): Schedule by INSN_COST.

8
gcc/testsuite/ChangeLog
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@ -1,3 +1,11 @@
2018-09-13 Richard Biener <rguenther@suse.de>
PR tree-optimization/87263
* gcc.dg/torture/pr87263.c: New testcase.
* gcc.dg/torture/ssa-fre-2.c: Likewise.
* gcc.dg/torture/ssa-fre-3.c: Likewise.
* gcc.dg/torture/ssa-fre-4.c: Likewise.
2018-09-13 Omar Sandoval <osandov@osandov.com>
Tom de Vries <tdevries@suse.de>

24
gcc/testsuite/gcc.dg/torture/pr87263.c Normal file
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@ -0,0 +1,24 @@
/* { dg-do compile } */
int a, b, c;
int main ()
{
int g, *h[3] = {&g, &g, &g};
if (h[2] == 0)
;
else
{
int i[1];
if (a)
while (a)
L:;
else
{
int k = b;
}
}
if ((b < c) > b)
goto L;
return 0;
}

21
gcc/testsuite/gcc.dg/torture/ssa-fre-2.c Normal file
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@ -0,0 +1,21 @@
/* { dg-do run } */
int x;
int main()
{
int i = 0;
x = 0;
if (x)
{
for (; i < 10; ++i)
{
doit:
x = i;
}
}
if (!x)
goto doit;
if (x != 9)
__builtin_abort ();
return 0;
}

23
gcc/testsuite/gcc.dg/torture/ssa-fre-3.c Normal file
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@ -0,0 +1,23 @@
/* { dg-do compile } */
/* { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
/* { dg-additional-options "-fdump-tree-fre1" } */
int x;
int main()
{
x = 0;
int z = x;
int w = 1;
for (int i = 0; i < 32; ++i)
{
if (z)
w = 2;
else
w = 1;
if (w == 2)
__builtin_abort ();
}
return w;
}
/* { dg-final { scan-tree-dump-not "abort" "fre1" } } */

17
gcc/testsuite/gcc.dg/torture/ssa-fre-4.c Normal file
View File

@ -0,0 +1,17 @@
/* { dg-do compile } */
/* { dg-skip-if "" { *-*-* } { "-O0" } { "" } } */
/* { dg-additional-options "-fdump-tree-fre1" } */
int x;
int main()
{
x = 0;
if (x)
{
for (int i = 0; i < 10; ++i)
x = i;
}
return x;
}
/* { dg-final { scan-tree-dump "return 0;" "fre1" } } */

279
gcc/tree-ssa-sccvn.c
View File

@ -4196,10 +4196,7 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
}
}
/* If the value we want to use is the backedge and that wasn't visited
yet or if we should take it as VARYING but it has a non-VARYING
value drop to VARYING. This only happens when not iterating.
If we value-number a virtual operand never value-number to the
/* If we value-number a virtual operand never value-number to the
value from the backedge as that confuses the alias-walking code.
See gcc.dg/torture/pr87176.c. If the value is the same on a
non-backedge everything is OK though. */
@ -4207,9 +4204,7 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
&& !seen_non_backedge
&& TREE_CODE (backedge_val) == SSA_NAME
&& sameval == backedge_val
&& (SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val)
|| !SSA_VISITED (backedge_val)
|| SSA_VAL (backedge_val) != backedge_val))
&& SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val))
/* Note this just drops to VARYING without inserting the PHI into
the hashes. */
result = PHI_RESULT (phi);
@ -6224,6 +6219,9 @@ struct unwind_state
/* Whether to handle this as iteration point or whether to treat
incoming backedge PHI values as varying. */
bool iterate;
/* Maximum RPO index this block is reachable from. */
int max_rpo;
/* Unwind state. */
void *ob_top;
vn_reference_t ref_top;
vn_phi_t phi_top;
@ -6309,8 +6307,8 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
}
int *rpo = XNEWVEC (int, n_basic_blocks_for_fn (fn) - NUM_FIXED_BLOCKS);
int n = rev_post_order_and_mark_dfs_back_seme (fn, entry, exit_bbs,
iterate, rpo);
int n = rev_post_order_and_mark_dfs_back_seme
(fn, entry, exit_bbs, !loops_state_satisfies_p (LOOPS_NEED_FIXUP), rpo);
/* rev_post_order_and_mark_dfs_back_seme fills RPO in reverse order. */
for (int i = 0; i < n / 2; ++i)
std::swap (rpo[i], rpo[n-i-1]);
@ -6380,6 +6378,7 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
{
basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[i]);
rpo_state[i].visited = 0;
rpo_state[i].max_rpo = i;
bb->flags &= ~BB_EXECUTABLE;
bool has_backedges = false;
edge e;
@ -6389,15 +6388,18 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
if (e->flags & EDGE_DFS_BACK)
has_backedges = true;
if (! iterate && (e->flags & EDGE_DFS_BACK))
{
e->flags |= EDGE_EXECUTABLE;
/* ??? Strictly speaking we only need to unconditionally
process a block when it is in an irreducible region,
thus when it may be reachable via the backedge only. */
bb->flags |= BB_EXECUTABLE;
}
e->flags |= EDGE_EXECUTABLE;
else
e->flags &= ~EDGE_EXECUTABLE;
if (e == entry)
continue;
if (bb_to_rpo[e->src->index] > i)
rpo_state[i].max_rpo = MAX (rpo_state[i].max_rpo,
bb_to_rpo[e->src->index]);
else
rpo_state[i].max_rpo
= MAX (rpo_state[i].max_rpo,
rpo_state[bb_to_rpo[e->src->index]].max_rpo);
}
rpo_state[i].iterate = iterate && has_backedges;
}
@ -6440,120 +6442,165 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
}
}
/* Go and process all blocks, iterating as necessary. */
int idx = 0;
uint64_t nblk = 0;
do
int idx = 0;
if (iterate)
/* Go and process all blocks, iterating as necessary. */
do
{
basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[idx]);
/* If the block has incoming backedges remember unwind state. This
is required even for non-executable blocks since in irreducible
regions we might reach them via the backedge and re-start iterating
from there.
Note we can individually mark blocks with incoming backedges to
not iterate where we then handle PHIs conservatively. We do that
heuristically to reduce compile-time for degenerate cases. */
if (rpo_state[idx].iterate)
{
rpo_state[idx].ob_top = obstack_alloc (&vn_tables_obstack, 0);
rpo_state[idx].ref_top = last_inserted_ref;
rpo_state[idx].phi_top = last_inserted_phi;
rpo_state[idx].nary_top = last_inserted_nary;
}
if (!(bb->flags & BB_EXECUTABLE))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Block %d: BB%d found not executable\n",
idx, bb->index);
idx++;
continue;
}
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Processing block %d: BB%d\n", idx, bb->index);
nblk++;
todo |= process_bb (avail, bb,
rpo_state[idx].visited != 0,
rpo_state[idx].iterate,
iterate, eliminate, do_region, exit_bbs);
rpo_state[idx].visited++;
/* Verify if changed values flow over executable outgoing backedges
and those change destination PHI values (that's the thing we
can easily verify). Reduce over all such edges to the farthest
away PHI. */
int iterate_to = -1;
edge_iterator ei;
edge e;
FOR_EACH_EDGE (e, ei, bb->succs)
if ((e->flags & (EDGE_DFS_BACK|EDGE_EXECUTABLE))
== (EDGE_DFS_BACK|EDGE_EXECUTABLE)
&& rpo_state[bb_to_rpo[e->dest->index]].iterate)
{
int destidx = bb_to_rpo[e->dest->index];
if (!rpo_state[destidx].visited)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Unvisited destination %d\n",
e->dest->index);
if (iterate_to == -1 || destidx < iterate_to)
iterate_to = destidx;
continue;
}
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Looking for changed values of backedge"
" %d->%d destination PHIs\n",
e->src->index, e->dest->index);
vn_context_bb = e->dest;
gphi_iterator gsi;
for (gsi = gsi_start_phis (e->dest);
!gsi_end_p (gsi); gsi_next (&gsi))
{
bool inserted = false;
/* While we'd ideally just iterate on value changes
we CSE PHIs and do that even across basic-block
boundaries. So even hashtable state changes can
be important (which is roughly equivalent to
PHI argument value changes). To not excessively
iterate because of that we track whether a PHI
was CSEd to with GF_PLF_1. */
bool phival_changed;
if ((phival_changed = visit_phi (gsi.phi (),
&inserted, false))
|| (inserted && gimple_plf (gsi.phi (), GF_PLF_1)))
{
if (!phival_changed
&& dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "PHI was CSEd and hashtable "
"state (changed)\n");
if (iterate_to == -1 || destidx < iterate_to)
iterate_to = destidx;
break;
}
}
vn_context_bb = NULL;
}
if (iterate_to != -1)
{
do_unwind (&rpo_state[iterate_to], iterate_to, avail, bb_to_rpo);
idx = iterate_to;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Iterating to %d BB%d\n",
iterate_to, rpo[iterate_to]);
continue;
}
idx++;
}
while (idx < n);
else /* !iterate */
{
basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[idx]);
/* If the block has incoming backedges remember unwind state. This
is required even for non-executable blocks since in irreducible
regions we might reach them via the backedge and re-start iterating
from there.
Note we can individually mark blocks with incoming backedges to
not iterate where we then handle PHIs conservatively. We do that
heuristically to reduce compile-time for degenerate cases. */
if (rpo_state[idx].iterate)
/* Process all blocks greedily with a worklist that enforces RPO
processing of reachable blocks. */
auto_bitmap worklist;
bitmap_set_bit (worklist, 0);
while (!bitmap_empty_p (worklist))
{
rpo_state[idx].ob_top = obstack_alloc (&vn_tables_obstack, 0);
rpo_state[idx].ref_top = last_inserted_ref;
rpo_state[idx].phi_top = last_inserted_phi;
rpo_state[idx].nary_top = last_inserted_nary;
}
int idx = bitmap_first_set_bit (worklist);
bitmap_clear_bit (worklist, idx);
basic_block bb = BASIC_BLOCK_FOR_FN (fn, rpo[idx]);
gcc_assert ((bb->flags & BB_EXECUTABLE)
&& !rpo_state[idx].visited);
if (!(bb->flags & BB_EXECUTABLE))
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Block %d: BB%d found not executable\n",
idx, bb->index);
idx++;
continue;
}
fprintf (dump_file, "Processing block %d: BB%d\n", idx, bb->index);
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Processing block %d: BB%d\n", idx, bb->index);
nblk++;
todo |= process_bb (avail, bb,
rpo_state[idx].visited != 0,
rpo_state[idx].iterate,
iterate, eliminate, do_region, exit_bbs);
rpo_state[idx].visited++;
if (iterate)
{
/* Verify if changed values flow over executable outgoing backedges
and those change destination PHI values (that's the thing we
can easily verify). Reduce over all such edges to the farthest
away PHI. */
int iterate_to = -1;
/* When we run into predecessor edges where we cannot trust its
executable state mark them executable so PHI processing will
be conservative.
??? Do we need to force arguments flowing over that edge
to be varying or will they even always be? */
edge_iterator ei;
edge e;
FOR_EACH_EDGE (e, ei, bb->succs)
if ((e->flags & (EDGE_DFS_BACK|EDGE_EXECUTABLE))
== (EDGE_DFS_BACK|EDGE_EXECUTABLE)
&& rpo_state[bb_to_rpo[e->dest->index]].iterate)
FOR_EACH_EDGE (e, ei, bb->preds)
if (!(e->flags & EDGE_EXECUTABLE)
&& !rpo_state[bb_to_rpo[e->src->index]].visited
&& rpo_state[bb_to_rpo[e->src->index]].max_rpo >= (int)idx)
{
int destidx = bb_to_rpo[e->dest->index];
if (!rpo_state[destidx].visited)
{
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Unvisited destination %d\n",
e->dest->index);
if (iterate_to == -1
|| destidx < iterate_to)
iterate_to = destidx;
continue;
}
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Looking for changed values of backedge "
"%d->%d destination PHIs\n",
fprintf (dump_file, "Cannot trust state of predecessor "
"edge %d -> %d, marking executable\n",
e->src->index, e->dest->index);
vn_context_bb = e->dest;
gphi_iterator gsi;
for (gsi = gsi_start_phis (e->dest);
!gsi_end_p (gsi); gsi_next (&gsi))
{
bool inserted = false;
/* While we'd ideally just iterate on value changes
we CSE PHIs and do that even across basic-block
boundaries. So even hashtable state changes can
be important (which is roughly equivalent to
PHI argument value changes). To not excessively
iterate because of that we track whether a PHI
was CSEd to with GF_PLF_1. */
bool phival_changed;
if ((phival_changed = visit_phi (gsi.phi (),
&inserted, false))
|| (inserted && gimple_plf (gsi.phi (), GF_PLF_1)))
{
if (!phival_changed
&& dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "PHI was CSEd and hashtable "
"state (changed)\n");
if (iterate_to == -1
|| destidx < iterate_to)
iterate_to = destidx;
break;
}
}
vn_context_bb = NULL;
e->flags |= EDGE_EXECUTABLE;
}
if (iterate_to != -1)
{
do_unwind (&rpo_state[iterate_to], iterate_to,
avail, bb_to_rpo);
idx = iterate_to;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Iterating to %d BB%d\n",
iterate_to, rpo[iterate_to]);
continue;
}
}
idx++;
nblk++;
todo |= process_bb (avail, bb, false, false, false, eliminate,
do_region, exit_bbs);
rpo_state[idx].visited++;
FOR_EACH_EDGE (e, ei, bb->succs)
if ((e->flags & EDGE_EXECUTABLE)
&& e->dest->index != EXIT_BLOCK
&& (!do_region || !bitmap_bit_p (exit_bbs, e->dest->index))
&& !rpo_state[bb_to_rpo[e->dest->index]].visited)
bitmap_set_bit (worklist, bb_to_rpo[e->dest->index]);
}
}
while (idx < n);
/* If statistics or dump file active. */
int nex = 0;