[Bug c/66348] Simple loop never exits with -O1, exits with -O0

["miyuki at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66348

Mikhail Maltsev <miyuki at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |miyuki at gcc dot gnu.org

--- Comment #10 from Mikhail Maltsev <miyuki at gcc dot gnu.org> ---
You should probably provide a reproducer:
1. Modify your program in such way that it does not require any user's action
and/or command line switches to exhibit the problem (i.e. it should either hang
or exit normally with code 0, depending on compiler flags used)
2. If your program requires some libraries (ncurses, or something like that),
try to comment-out library calls or write some simple stubs insead of them.
3. It should not require any external files. If it does, try to hardcode all
data into the program (e.g., if your text editor requires a file to be opened,
use a static char array, which will contain that file).
4. It sould compile without any external headers. To achive this, just run each
of your sources through preprocessor, like this:
gcc -std=c99 -D_GNU_SOURCE -D__USE_GNU -DSTDC_HEADERS -Dinline=__inline__ -O1
-DNDEBUG -E buffer.c > buffer.i
5. Just in case, ensure that the bug still persists: compile the preprocessed
sources and check that behavior did not change.
6. Compress all preprocessed sources and attach the archive.