[Bug rtl-optimization/68691] New: ICE at -O3 with -g enabled on x86_64-linux-gnu in alter_subregs, at lra-spills.c:610 (in 32-bit mode)

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68691

            Bug ID: 68691
           Summary: ICE at -O3 with -g enabled on x86_64-linux-gnu in
                    alter_subregs, at lra-spills.c:610 (in 32-bit mode)
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following code causes an ICE when compiled with the current gcc trunk at
-O3 with -g enabled on x86_64-linux-gnu in the 32-bit mode (but not in 64-bit
mode). 

It is a regression from 5.2.x.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20151203 (experimental) [trunk revision 231219] (GCC) 
$ 
$ gcc-trunk -m32 -O2 -g -c small.c
$ gcc-trunk -m64 -O3 -g -c small.c
$ gcc-5.2 -m32 -O3 -g -c small.c
$ 
$ gcc-trunk -m32 -O3 -g -c small.c
small.c: In function ‘fn1’:
small.c:39:1: internal compiler error: in alter_subregs, at lra-spills.c:610
 }
 ^

0x9a4ccd alter_subregs
        ../../gcc-trunk/gcc/lra-spills.c:610
0x9a5f32 lra_final_code_change()
        ../../gcc-trunk/gcc/lra-spills.c:745
0x9868dc lra(_IO_FILE*)
        ../../gcc-trunk/gcc/lra.c:2383
0x93c449 do_reload
        ../../gcc-trunk/gcc/ira.c:5383
0x93c449 execute
        ../../gcc-trunk/gcc/ira.c:5554
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$ 


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


char a, b, i, j;
int c, d, e, f, g, h, n;

char
fn1 ()
{
  char k, l, m;
  int p;
  e = g > f;
  for (b = 0; b < 2; b++)
    {
      for (p = 0; p < 3; p++)
        {
          for (; h < 1; h++)
            {
              for (; m;)
                goto lbl;
              e = g;
            }
          l = a < 0 || a < d;
        }
      d++;
      for (;;)
        {
          k = g;
          n = -k;
          j = n;
          c = j;
          e = 2;
          if (l)
            break;
          return 2;
        }
    }
  for (;;)
    ;
lbl:
  return i;
}