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re PR debug/90131 (wrong debug info at -O3) 

2019-04-18  Richard Biener  <rguenther@suse.de>

	PR debug/90131
	* tree-cfgcleanup.c (move_debug_stmts_from_forwarder): Split
	out from ...
	(remove_forwarder_block): ... here.
	(remove_forwarder_block_with_phi): Also move debug stmts here.

	* gcc.dg/guality/pr90131.c: New testcase.

From-SVN: r270441
This commit is contained in:
Richard Biener 2019-04-18 12:02:40 +00:00 committed by Richard Biener
parent 9574af76fa
commit e62817edae
4 changed files with 92 additions and 37 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2019-04-18 Richard Biener <rguenther@suse.de>
PR debug/90131
* tree-cfgcleanup.c (move_debug_stmts_from_forwarder): Split
out from ...
(remove_forwarder_block): ... here.
(remove_forwarder_block_with_phi): Also move debug stmts here.
2019-04-18 Jakub Jelinek <jakub@redhat.com>
PR translation/79183

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2019-04-18 Richard Biener <rguenther@suse.de>
PR debug/90131
* gcc.dg/guality/pr90131.c: New testcase.
2019-04-17 Jakub Jelinek <jakub@redhat.com>
PR c++/89325

35
gcc/testsuite/gcc.dg/guality/pr90131.c Normal file
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@ -0,0 +1,35 @@
/* { dg-do run } */
/* { dg-options "-g" } */
void __attribute__((noinline))
optimize_me_not ()
{
__asm__ volatile ("" : : : "memory");
}
volatile long a;
int b[9][1];
static short c[2][1] = {3};
int main()
{
int i, d, e;
i = 0;
for (; i < 9; i++)
a = b[i][0];
i = 0;
for (; i < 2; i++)
{
d = 0;
for (; d < 1; d++)
{
e = 0;
for (; e < 1; e++)
a = c[i][e];
/* i may very well be optimized out, so we cannot test for i == 0.
Instead test i + 1 which will make the test UNSUPPORTED if i
is optimized out. Since the test previously had wrong debug
with i == 9 this is acceptable. */
optimize_me_not(); /* { dg-final { gdb-test . "i + 1" "1" } } */
}
}
return 0;
}

81
gcc/tree-cfgcleanup.c
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@ -444,6 +444,45 @@ phi_alternatives_equal (basic_block dest, edge e1, edge e2)
return true;
}
/* Move debug stmts from the forwarder block SRC to DEST. */
static void
move_debug_stmts_from_forwarder (basic_block src, basic_block dest)
{
if (!MAY_HAVE_DEBUG_STMTS)
return;
bool can_move_debug_stmts = single_pred_p (dest);
gimple_stmt_iterator gsi_to = gsi_after_labels (dest);
for (gimple_stmt_iterator gsi = gsi_after_labels (src); !gsi_end_p (gsi);)
{
gimple *debug = gsi_stmt (gsi);
gcc_assert (is_gimple_debug (debug));
/* Move debug binds anyway, but not anything else like begin-stmt
markers unless they are always valid at the destination. */
if (can_move_debug_stmts
|| gimple_debug_bind_p (debug))
{
gsi_move_before (&gsi, &gsi_to);
/* Reset debug-binds that are not always valid at the destination.
Simply dropping them can cause earlier values to become live,
generating wrong debug information.
??? There are several things we could improve here. For
one we might be able to move stmts to the predecessor.
For anther, if the debug stmt is immediately followed by a
(debug) definition in the destination (on a post-dominated path?)
we can elide it without any bad effects. */
if (!can_move_debug_stmts)
{
gimple_debug_bind_reset_value (debug);
update_stmt (debug);
}
}
else
gsi_next (&gsi);
}
}
/* Removes forwarder block BB. Returns false if this failed. */
static bool
@ -454,7 +493,6 @@ remove_forwarder_block (basic_block bb)
gimple *stmt;
edge_iterator ei;
gimple_stmt_iterator gsi, gsi_to;
bool can_move_debug_stmts;
/* We check for infinite loops already in tree_forwarder_block_p.
However it may happen that the infinite loop is created
@ -503,8 +541,6 @@ remove_forwarder_block (basic_block bb)
}
}
can_move_debug_stmts = MAY_HAVE_DEBUG_STMTS && single_pred_p (dest);
basic_block pred = NULL;
if (single_pred_p (bb))
pred = single_pred (bb);
@ -566,40 +602,7 @@ remove_forwarder_block (basic_block bb)
/* Move debug statements. Reset them if the destination does not
have a single predecessor. */
if (!gsi_end_p (gsi))
{
gsi_to = gsi_after_labels (dest);
do
{
gimple *debug = gsi_stmt (gsi);
gcc_assert (is_gimple_debug (debug));
/* Move debug binds anyway, but not anything else
like begin-stmt markers unless they are always
valid at the destination. */
if (can_move_debug_stmts
|| gimple_debug_bind_p (debug))
{
gsi_move_before (&gsi, &gsi_to);
/* Reset debug-binds that are not always valid at the
destination. Simply dropping them can cause earlier
values to become live, generating wrong debug information.
??? There are several things we could improve here. For
one we might be able to move stmts to the predecessor.
For anther, if the debug stmt is immediately followed
by a (debug) definition in the destination (on a
post-dominated path?) we can elide it without any bad
effects. */
if (!can_move_debug_stmts)
{
gimple_debug_bind_reset_value (debug);
update_stmt (debug);
}
}
else
gsi_next (&gsi);
}
while (!gsi_end_p (gsi));
}
move_debug_stmts_from_forwarder (bb, dest);
bitmap_set_bit (cfgcleanup_altered_bbs, dest->index);
@ -1282,6 +1285,10 @@ remove_forwarder_block_with_phi (basic_block bb)
redirect_edge_var_map_clear (e);
}
/* Move debug statements. Reset them if the destination does not
have a single predecessor. */
move_debug_stmts_from_forwarder (bb, dest);
/* Update the dominators. */
dombb = get_immediate_dominator (CDI_DOMINATORS, bb);
domdest = get_immediate_dominator (CDI_DOMINATORS, dest);