[Bug tree-optimization/69214] New: ICE (segfault) at -Os on x86_64-linux-gnu in "fail_abnormal_edge_coalesce"

["helloqirun at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69214

            Bug ID: 69214
           Summary: ICE (segfault) at -Os on x86_64-linux-gnu in
                    "fail_abnormal_edge_coalesce"
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

The following code causes an ICE when compiled with the current gcc trunk at
-Os  on x86_64-linux-gnu in 64-bit mode.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20160109 (experimental) [trunk revision 232190] (GCC)



$ gcc-trunk -c -Os abc.c

Unable to coalesce ssa_names 2 and 17 which are marked as MUST COALESCE.
d_2(ab) and  d_17(ab)
abc.c: In function 'foo':
abc.c:8:6: internal compiler error: SSA corruption
 void foo (struct A *x)
      ^~~

0xc3eb26 fail_abnormal_edge_coalesce
        ../../gcc/gcc/tree-ssa-coalesce.c:936
0xc3eb26 coalesce_partitions
        ../../gcc/gcc/tree-ssa-coalesce.c:1337
0xc3eb26 coalesce_ssa_name()
        ../../gcc/gcc/tree-ssa-coalesce.c:1821
0xbcf7d0 remove_ssa_form
        ../../gcc/gcc/tree-outof-ssa.c:974
0xbcf7d0 rewrite_out_of_ssa(ssaexpand*)
        ../../gcc/gcc/tree-outof-ssa.c:1198
0x747ad0 execute
        ../../gcc/gcc/cfgexpand.c:6124
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.



---------
$ cat abc.c

extern int setjmp (int);
extern int fun1 (int);
extern int *fun2 (void);

struct A {unsigned a;};

void foo (struct A *x)
{
  int d = 0;
  long f = 0;
  setjmp (*fun2());
  f = d;
  d = 8;
  ((x->a) && !f && fun1 (d));
}