-gstatement-frontiers vs. -fselective-scheduling* (PR debug/83480)

Hi!

As the testcase shows, the sel-sched.c framework can't deal with debugging
insns without causing -fcompare-debug failures, and I presume also with
debug markers, with which it causes even ICEs right now.

The following patch just follows what we do for -fvar-tracking-assignments,
disable it by default if -fselective-scheduling*.  It isn't a complete fix,
the testcase will still ICE with explicit -fselective-scheduling{,2}
-gstatement-frontiers, but at least it won't ICE that often and even if the
ICE is fixed, it is quite unlikely that debug marker handling would
work with -fcompare-debug when other debug insns don't work with that.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2018-01-05  Jakub Jelinek  <jakub@redhat.com>

	PR debug/83480
	* toplev.c (process_options): Don't enable debug_nonbind_markers_p
	by default if flag_selective_schedling{,2}.  Formatting fixes.

	* gcc.dg/pr83480.c: New test.


	Jakub

On January 5, 2018 11:10:26 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>As the testcase shows, the sel-sched.c framework can't deal with
>debugging
>insns without causing -fcompare-debug failures, and I presume also with
>debug markers, with which it causes even ICEs right now.
>
>The following patch just follows what we do for
>-fvar-tracking-assignments,
>disable it by default if -fselective-scheduling*.  It isn't a complete
>fix,
>the testcase will still ICE with explicit -fselective-scheduling{,2}
>-gstatement-frontiers, but at least it won't ICE that often and even if
>the
>ICE is fixed, it is quite unlikely that debug marker handling would
>work with -fcompare-debug when other debug insns don't work with that.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

Richard. 


>2018-01-05  Jakub Jelinek  <jakub@redhat.com>
>
>	PR debug/83480
>	* toplev.c (process_options): Don't enable debug_nonbind_markers_p
>	by default if flag_selective_schedling{,2}.  Formatting fixes.
>
>	* gcc.dg/pr83480.c: New test.
>
>--- gcc/toplev.c.jj	2018-01-03 10:19:54.453533845 +0100
>+++ gcc/toplev.c	2018-01-05 16:20:56.130195110 +0100
>@@ -1535,8 +1535,9 @@ process_options (void)
>     flag_var_tracking_uninit = flag_var_tracking;
> 
>   if (flag_var_tracking_assignments == AUTODETECT_VALUE)
>-    flag_var_tracking_assignments = flag_var_tracking
>-      && !(flag_selective_scheduling || flag_selective_scheduling2);
>+    flag_var_tracking_assignments
>+      = (flag_var_tracking
>+	 && !(flag_selective_scheduling || flag_selective_scheduling2));
> 
>   if (flag_var_tracking_assignments_toggle)
>     flag_var_tracking_assignments = !flag_var_tracking_assignments;
>@@ -1550,8 +1551,12 @@ process_options (void)
> 		"var-tracking-assignments changes selective scheduling");
> 
>   if (debug_nonbind_markers_p == AUTODETECT_VALUE)
>-    debug_nonbind_markers_p = optimize && debug_info_level >=
>DINFO_LEVEL_NORMAL
>-      && (write_symbols == DWARF2_DEBUG || write_symbols ==
>VMS_AND_DWARF2_DEBUG);
>+    debug_nonbind_markers_p
>+      = (optimize
>+	 && debug_info_level >= DINFO_LEVEL_NORMAL
>+	 && (write_symbols == DWARF2_DEBUG
>+	     || write_symbols == VMS_AND_DWARF2_DEBUG)
>+	 && !(flag_selective_scheduling || flag_selective_scheduling2));
> 
>   if (flag_tree_cselim == AUTODETECT_VALUE)
>     {
>--- gcc/testsuite/gcc.dg/pr83480.c.jj	2018-01-05 16:24:14.444290629
>+0100
>+++ gcc/testsuite/gcc.dg/pr83480.c	2018-01-05 16:23:40.631274338 +0100
>@@ -0,0 +1,32 @@
>+/* PR debug/83480 */
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -g -fselective-scheduling2 -ftree-vectorize
>-freorder-blocks-algorithm=simple -fnon-call-exceptions
>-fno-guess-branch-probability -fno-peephole2 -fno-tree-sink
>-fno-tree-scev-cprop" } */
>+
>+signed char a, b;
>+
>+void
>+foo (int x, int y)
>+{
>+  for (a = 1; a != 0; ++a)
>+    ;
>+
>+  for (;;)
>+    {
>+      int c;
>+
>+      b %= (y != 0 && a != 0) + 1;
>+      if (a != 0)
>+	y = b;
>+
>+      for (c = 0; c < 50; ++c)
>+	++x;
>+
>+      if (a < 1)
>+	{
>+	  while (x != 0)
>+	    ;
>+
>+	  a /= 0;	/* { dg-warning "division by zero" } */
>+	}
>+    }
>+}
>
>	Jakub