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if-conv: Delete dead stmts backwards in ifcvt_local_dce [PR94283]

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> > This patch caused:
> >
> > gcc /home/marxin/Programming/gcc/gcc/testsuite/gcc.c-torture/compile/990625-2.c -O3 -g -fno-tree-dce -c
> > during GIMPLE pass: ifcvt
> > /home/marxin/Programming/gcc/gcc/testsuite/gcc.c-torture/compile/990625-2.c: In function ‘broken030599’:
> > /home/marxin/Programming/gcc/gcc/testsuite/gcc.c-torture/compile/990625-2.c:2:1: internal compiler error: Segmentation fault
>
> Likely
>
>   /* Delete dead statements.  */
>   gsi = gsi_start_bb (bb);
>   while (!gsi_end_p (gsi))
>     {
>
> needs to instead work back-to-front for debug stmt adjustment to work

Indeed, that seems to work.

2020-03-25  Richard Biener  <rguenther@suse.de>
	    Jakub Jelinek  <jakub@redhat.com>

	PR debug/94283
	* tree-if-conv.c (ifcvt_local_dce): Delete dead statements backwards.

	* gcc.dg/pr94283.c: New test.

Co-authored-by: Richard Biener <rguenther@suse.de>
This commit is contained in:
Jakub Jelinek 2020-03-25 08:08:04 +01:00
parent adaf4b6c66
commit c2133167ad
4 changed files with 33 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2020-03-25 Richard Biener <rguenther@suse.de>
Jakub Jelinek <jakub@redhat.com>
PR debug/94283
* tree-if-conv.c (ifcvt_local_dce): Delete dead statements backwards.
2020-03-24 Christophe Lyon <christophe.lyon@linaro.org>
* doc/sourcebuild.texi (ARM-specific attributes): Add

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2020-03-25 Jakub Jelinek <jakub@redhat.com>
PR debug/94283
* gcc.dg/pr94283.c: New test.
2020-03-24 Sandra Loosemore <sandra@codesourcery.com>
* gcc.dg/analyzer/sigsetjmp-5.c: Require sigsetjmp support.

16
gcc/testsuite/gcc.dg/pr94283.c Normal file
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@ -0,0 +1,16 @@
/* PR debug/94283 */
/* { dg-do compile } */
/* { dg-options "-O3 -fno-tree-dce -fcompare-debug" } */
void
foo (int *n)
{
for (int i = 0; i < 32; i++)
{
int x = 0;
x++;
if (i & 4)
x++;
x++;
}
}

10
gcc/tree-if-conv.c
View File

@ -2973,9 +2973,11 @@ ifcvt_local_dce (class loop *loop)
}
}
/* Delete dead statements. */
gsi = gsi_start_bb (bb);
gsi = gsi_last_bb (bb);
while (!gsi_end_p (gsi))
{
gimple_stmt_iterator gsiprev = gsi;
gsi_prev (&gsiprev);
stmt = gsi_stmt (gsi);
if (gimple_store_p (stmt))
{
@ -2986,14 +2988,13 @@ ifcvt_local_dce (class loop *loop)
if (dse_classify_store (&write, stmt, false, NULL, NULL, latch_vdef)
== DSE_STORE_DEAD)
delete_dead_or_redundant_assignment (&gsi, "dead");
else
gsi_next (&gsi);
gsi = gsiprev;
continue;
}
if (gimple_plf (stmt, GF_PLF_2))
{
gsi_next (&gsi);
gsi = gsiprev;
continue;
}
if (dump_file && (dump_flags & TDF_DETAILS))
@ -3003,6 +3004,7 @@ ifcvt_local_dce (class loop *loop)
}
gsi_remove (&gsi, true);
release_defs (stmt);
gsi = gsiprev;
}
}