[llvm-bugs] [Bug 39199] New: Segmentation fault with -O2

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39199

            Bug ID: 39199
           Summary: Segmentation fault with -O2
           Product: new-bugs
           Version: 7.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: dcb314 at hotmail.com
                CC: llvm-bugs at lists.llvm.org

This C code:

int a[ 1];
int b;
void c() {
  void *d = b = 0;
  for (;; b++)
    a[b] = (int) d++;
}

seems to compile ok without optimiser on clang-7:

$ clang -c -w option-5d5829.c 
$  

but then the optimiser doesn't seem to like it:

$ clang -c -w -O2 option-5d5829.c
Stack dump:
0.      Program arguments: /usr/bin/clang-7 -cc1 -triple
x86_64-unknown-linux-gn
u -emit-obj -disable-free -disable-llvm-verifier -discard-value-names
-main-file
-name option-5d5829.c -mrelocation-model static -mthread-model posix
-fmath-errn
o -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array
-target-c
pu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer
-cov
erage-notes-file /home/dcb/creduce/dcbTest/option-5d5829.gcno -resource-dir
/usr
/lib64/clang/7.0.0 -internal-isystem /usr/local/include -internal-isystem
/usr/l
ib64/clang/7.0.0/include -internal-externc-isystem /include
-internal-externc-is
ystem /usr/include -O2 -w -fdebug-compilation-dir /home/dcb/creduce/dcbTest
-fer
ror-limit 19 -fmessage-length 0 -fobjc-runtime=gcc -fdiagnostics-show-option
-ve
ctorize-loops -vectorize-slp -o option-5d5829.o -x c option-5d5829.c -faddrsig 
1.      <eof> parser at end of file
2.      Per-module optimization passes
3.      Running pass 'CallGraph Pass Manager' on module 'option-5d5829.c'.
4.      Running pass 'Loop Pass Manager' on function '@c'

...

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