Re: optimization/9421: gcc 3.4: infinite loop in gcse

Re: optimization/9421: gcc 3.4: infinite loop in gcse

[ebotcazou]

Synopsis: gcc 3.4: infinite loop in gcse

State-Changed-From-To: open->closed
State-Changed-By: ebotcazou
State-Changed-When: Thu Jan 23 17:58:29 2003
State-Changed-Why:
    Duplicate of PR optimization/8492

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9421

optimization/9421: gcc 3.4: infinite loop in gcse

[snyder]

>Number:         9421
>Category:       optimization
>Synopsis:       gcc 3.4: infinite loop in gcse
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jan 23 17:46:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     scott snyder
>Release:        3.4 20030123 (experimental)
>Organization:
<organization of PR author (multiple lines)>
>Environment:
System: Linux karma 2.4.19-emp_2419p5a829i #1 Tue Sep 3 17:42:17 EST 2002 i686 unknown
Architecture: i686

	<machine, os, target, libraries (multiple lines)>
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long : (reconfigured) 
>Description:

When the following source is compiled with -O2 or above, the compiler
never terminates.

$ ./cc1 -O2 x.c
...

Here's where it seems to be getting stuck (halting it from within
the debugger):

Program received signal SIGINT, Interrupt.
0x081c5fa3 in find_avail_set (regno=59, insn=0x4001570c)
    at ../../gcc/gcc/gcse.c:3989
3989	      struct expr *set = lookup_set (regno, NULL_RTX, &set_hash_table);
(gdb) where
#0  0x081c5fa3 in find_avail_set (regno=59, insn=0x4001570c)
    at ../../gcc/gcc/gcse.c:3989
#1  0x081c6546 in cprop_insn (insn=0x4001570c, alter_jumps=1)
    at ../../gcc/gcc/gcse.c:4196
#2  0x081c6d5e in cprop (alter_jumps=1) at ../../gcc/gcc/gcse.c:4452
#3  0x081c6e62 in one_cprop_pass (pass=1, cprop_jumps=1, bypass_jumps=1)
    at ../../gcc/gcc/gcse.c:4494
#4  0x081cbd81 in bypass_jumps (file=0x0) at ../../gcc/gcc/gcse.c:7441
#5  0x0835cbcd in rest_of_compilation (decl=0x4004bb60)
    at ../../gcc/gcc/toplev.c:2985
...


>How-To-Repeat:

------------------
extern int tolower (int __c);

void foo(int type)
{
  type = 
  (__extension__							      
   ({ int __res;							      
   if (__builtin_constant_p (type))
     __res = type;
   else								      
     __res = tolower (type);					      
   __res;
   }));
}

------------------

>Fix:
	<how to correct or work around the problem, if known (multiple lines)>
>Release-Note:
>Audit-Trail:
>Unformatted: