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[Bug tree-optimization/63288] New: [5 Regression] gcc.c-torture/execute/20140326-1.c FAILs with -Og -fgcse -fif-conversion2


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63288

            Bug ID: 63288
           Summary: [5 Regression] gcc.c-torture/execute/20140326-1.c
                    FAILs with -Og -fgcse -fif-conversion2
           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 33508
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33508&action=edit
reduced testcase

Output:
$ gcc -Og -fgcse -fif-conversion2 testcase.c
$ valgrind -q ./a.out 
==13302== Invalid read of size 1
==13302==    at 0x400528: main (in /home/smatz/gcc-bug/1278/a.out)
==13302==  Address 0xfff01f9d8 is not stack'd, malloc'd or (recently) free'd
==13302== 
==13302== 
==13302== Process terminating with default action of signal 11 (SIGSEGV)
==13302==  Access not within mapped region at address 0xFFF01F9D8
==13302==    at 0x400528: main (in /home/smatz/gcc-bug/1278/a.out)
==13302==  If you believe this happened as a result of a stack
==13302==  overflow in your program's main thread (unlikely but
==13302==  possible), you can try to increase the size of the
==13302==  main thread stack using the --main-stacksize= flag.
==13302==  The main thread stack size used in this run was 8388608.
Segmentation fault

The segfault caused by e[131072] being speculatively loaded before the
comparison:

main:
    # crashes here
    movzx    eax, BYTE PTR [rsp+131056]
    cmp    DWORD PTR a[rip], 131072
    je    .L2
        mov    eax, 0
.L2:
    movsx    eax, al
    ret

Tested revisions:
r215315 - fail
r214876 - fail
4_9 r213788 - OK


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