[Bug c/63843] New: wrong code generation at -O1 and higher

[mednafen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63843

            Bug ID: 63843
           Summary: wrong code generation at -O1 and higher
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mednafen at gmail dot com

Created attachment 33955
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33955&action=edit
Testcase, good output is 8181.

trunk revision 217451
gcc (GCC) 5.0.0 20141112 (experimental)
Linux x86_64

$ ~mednafen/gcc-dev/bin/gcc -O0 -o tc tc.c
$ ./tc
8181

$ ~mednafen/gcc-dev/bin/gcc -O1 -o tc tc.c
$ ./tc 
ff81

$ ~mednafen/gcc-dev/bin/gcc -O1 -fno-tree-copyrename -o tc tc.c
$ ./tc 
8181