[Bug tree-optimization/64121] New: [5 Regression] ICE: SSA corruption with -O -fsanitize=undefined

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64121

            Bug ID: 64121
           Summary: [5 Regression] ICE: SSA corruption with -O
                    -fsanitize=undefined
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz

Created attachment 34145
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34145&action=edit
reduced testcase

Compiler output:
$ gcc -O -fsanitize=undefined testcase.c         

Unable to coalesce ssa_names 1 and 6 which are marked as MUST COALESCE.
xp_1(ab) and  xp_6(ab)
testcase.c: In function 'execute':
testcase.c:4:1: internal compiler error: SSA corruption
 execute (int *ip, int x)
 ^
0xd2c828 fail_abnormal_edge_coalesce
        /mnt/svn/gcc-trunk/gcc/tree-ssa-coalesce.c:921
0xd2c828 coalesce_partitions
        /mnt/svn/gcc-trunk/gcc/tree-ssa-coalesce.c:1219
0xd2c828 coalesce_ssa_name()
        /mnt/svn/gcc-trunk/gcc/tree-ssa-coalesce.c:1364
0xcc27cf remove_ssa_form
        /mnt/svn/gcc-trunk/gcc/tree-outof-ssa.c:999
0xcc27cf rewrite_out_of_ssa(ssaexpand*)
        /mnt/svn/gcc-trunk/gcc/tree-outof-ssa.c:1233
0x7d3c37 execute
        /mnt/svn/gcc-trunk/gcc/cfgexpand.c:5703
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.

Tested revisions:
r218181 - ICE
4_9 r218177 - OK