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re PR tree-optimization/78185 (Wrong branch optimization with -O1 on x86/x86_64) 

2016-11-04  Richard Biener  <rguenther@suse.de>

	PR middle-end/78185
	* loop-invariant.c (find_exits): Record entering inner
	loops as possibly exiting to handle infinite sub-loops.
	* tree-ssa-loop-im.c: Include tree-ssa-loop-niter.h.
	(fill_always_executed_in_1): Honor infinite child loops.

	* gcc.dg/pr78185.c: New testcase.

From-SVN: r241841
This commit is contained in:
Richard Biener 2016-11-04 08:54:42 +00:00 committed by Richard Biener
parent b07aafb1ac
commit 964ef24cd5
5 changed files with 63 additions and 9 deletions
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8
gcc/ChangeLog
View File

@ -1,3 +1,11 @@
2016-11-04 Richard Biener <rguenther@suse.de>
PR middle-end/78185
* loop-invariant.c (find_exits): Record entering inner
loops as possibly exiting to handle infinite sub-loops.
* tree-ssa-loop-im.c: Include tree-ssa-loop-niter.h.
(fill_always_executed_in_1): Honor infinite child loops.
2016-11-03 Michael Meissner <meissner@linux.vnet.ibm.com>
PR target/78192

18
gcc/loop-invariant.c
View File

@ -598,13 +598,17 @@ find_exits (struct loop *loop, basic_block *body,
FOR_EACH_EDGE (e, ei, body[i]->succs)
{
if (flow_bb_inside_loop_p (loop, e->dest))
continue;
bitmap_set_bit (may_exit, i);
bitmap_set_bit (has_exit, i);
outermost_exit = find_common_loop (outermost_exit,
e->dest->loop_father);
if (! flow_bb_inside_loop_p (loop, e->dest))
{
bitmap_set_bit (may_exit, i);
bitmap_set_bit (has_exit, i);
outermost_exit = find_common_loop (outermost_exit,
e->dest->loop_father);
}
/* If we enter a subloop that might never terminate treat
it like a possible exit. */
if (flow_loop_nested_p (loop, e->dest->loop_father))
bitmap_set_bit (may_exit, i);
}
continue;
}

5
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,8 @@
2016-11-04 Richard Biener <rguenther@suse.de>
PR middle-end/78185
* gcc.dg/pr78185.c: New testcase.
2016-10-04 David Edelsohn <dje.gcc@gmail.com>
* g++.dg/debug/dwarf2/ref-3.C: XFAIL AIX.

28
gcc/testsuite/gcc.dg/pr78185.c Normal file
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@ -0,0 +1,28 @@
/* { dg-do run { target *-*-linux* *-*-gnu* } } */
/* { dg-options "-O" } */
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
static char var1 = 0L;
static char *var2 = &var1;
void do_exit (int i)
{
exit (0);
}
int main(void)
{
struct sigaction s;
sigemptyset (&s.sa_mask);
s.sa_handler = do_exit;
s.sa_flags = 0;
sigaction (SIGALRM, &s, NULL);
alarm (1);
/* The following loop is infinite, the division by zero should not
be hoisted out of it. */
for (; (var1 == 0 ? 0 : (100 / var1)) == *var2; );
return 0;
}

13
gcc/tree-ssa-loop-im.c
View File

@ -44,6 +44,7 @@ along with GCC; see the file COPYING3. If not see
#include "trans-mem.h"
#include "gimple-fold.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-loop-niter.h"
/* TODO: Support for predicated code motion. I.e.
@ -2369,8 +2370,16 @@ fill_always_executed_in_1 (struct loop *loop, sbitmap contains_call)
break;
FOR_EACH_EDGE (e, ei, bb->succs)
if (!flow_bb_inside_loop_p (loop, e->dest))
break;
{
/* If there is an exit from this BB. */
if (!flow_bb_inside_loop_p (loop, e->dest))
break;
/* Or we enter a possibly non-finite loop. */
if (flow_loop_nested_p (bb->loop_father,
e->dest->loop_father)
&& ! finite_loop_p (e->dest->loop_father))
break;
}
if (e)
break;