[Bug middle-end/44102] ICE with asm goto + __builtin_unreachable () in C++

[Bug middle-end/44102] ICE with asm goto + __builtin_unreachable () in C++

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44102

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
   Last reconfirmed|                            |2012-11-30
                 CC|                            |steven at gcc dot gnu.org
         Resolution|FIXED                       |
     Ever Confirmed|0                           |1

--- Comment #3 from Steven Bosscher <steven at gcc dot gnu.org> 2012-11-30 14:19:29 UTC ---
This fix is wrong.
(http://gcc.gnu.org/viewcvs?view=revision&revision=159495)

There is a check at the start of cleanup_cfg to always set the
CLEANUP_CFGLAYOUT flag whenever we're in cfglayout mode:

120893     steven   /* Set the cfglayout mode flag here.  We could update all
the callers
120893     steven      but that is just inconvenient, especially given that we
eventually
120893     steven      want to have cfglayout mode as the default.  */
120893     steven   if (current_ir_type () == IR_RTL_CFGLAYOUT)
120893     steven     mode |= CLEANUP_CFGLAYOUT;
120893     steven


So this part of your fix:

-          if ((mode & CLEANUP_CFGLAYOUT)
+              if (current_ir_type () == IR_RTL_CFGLAYOUT)

is incorrect.

[Bug middle-end/44102] ICE with asm goto + __builtin_unreachable () in C++

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44102

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Steven Bosscher from comment #3)
> This fix is wrong.
> (http://gcc.gnu.org/viewcvs?view=revision&revision=159495)
> 
> There is a check at the start of cleanup_cfg to always set the
> CLEANUP_CFGLAYOUT flag whenever we're in cfglayout mode:
> 
> 120893     steven   /* Set the cfglayout mode flag here.  We could update
> all the callers
> 120893     steven      but that is just inconvenient, especially given that
> we eventually
> 120893     steven      want to have cfglayout mode as the default.  */
> 120893     steven   if (current_ir_type () == IR_RTL_CFGLAYOUT)
> 120893     steven     mode |= CLEANUP_CFGLAYOUT;
> 120893     steven
> 
> 
> So this part of your fix:
> 
> -		  if ((mode & CLEANUP_CFGLAYOUT)
> +		      if (current_ir_type () == IR_RTL_CFGLAYOUT)
> 
> is incorrect.

So the way I read this is that the fix is not wrong, just it uses the new check
instead of the old way. Now I am not sure what about the status of always using
cfglayout because what I remember is that is used all the way until post
reload(RA) now.

[Bug middle-end/44102] New: ICE with asm goto + __builtin_unreachable () in C++

[jakub at gcc dot gnu dot org]

// { dg-do compile }
// { dg-options "-O2" }

void baz (void);
struct A { A (); ~A (); };

static inline int
foo (void)
{
  asm goto ("" : : : : l1, l2);
  __builtin_unreachable ();
 l1:
  return 1;
 l2:
  return 0;
}

int
bar (int x)
{
  if (x == 5)
    {
      A a, b;
      baz ();
    }
  if (foo () || x == 6)
    x = 1;
  else
    x = 2;
  return x;
}

ICEs at -O2.  The problem is that RTL EH pass deletes the empty basic block
before getting into cfglayout mode, and while deleting empty bbs in cfglayout
mode apparently works, it doesn't work in normal rtl mode (when BB_HEAD ==
BB_END).  The following barrier is deleted too and nothing readds it after the
precious bb (the one ending with the asm goto).


-- 
           Summary: ICE with asm goto + __builtin_unreachable () in C++
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jakub at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44102

[Bug middle-end/44102] ICE with asm goto + __builtin_unreachable () in C++

[jakub at gcc dot gnu dot org]

------- Comment #1 from jakub at gcc dot gnu dot org  2010-05-17 17:18 -------
Subject: Bug 44102

Author: jakub
Date: Mon May 17 17:18:24 2010
New Revision: 159495

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=159495
Log:
        PR middle-end/44102
        * cfgcleanup.c (try_optimize_cfg): When removing trivially empty
        bb with no successors, move footer whenever in IR_RTL_CFGLAYOUT
        mode, not just when CLEANUP_CFGLAYOUT, and when in IR_RTL_CFGRTL
        add BARRIER after previous bb if needed.

        * g++.dg/ext/asmgoto1.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/ext/asmgoto1.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cfgcleanup.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44102

[Bug middle-end/44102] ICE with asm goto + __builtin_unreachable () in C++

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2010-05-17 17:34 -------
On branches/gcc-4_5-branch fixed by
http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=159499


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44102