[Bug c++/99375] New: Segmentation fault in code compiled with -O1 -ftree-loop-vectorize

["Arfrever.FTA at GMail dot Com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99375

            Bug ID: 99375
           Summary: Segmentation fault in code compiled with -O1
                    -ftree-loop-vectorize
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Arfrever.FTA at GMail dot Com
  Target Milestone: ---

For MARISA project (https://github.com/s-yata/marisa-trie), GCC 10.2.0 with at
least CXXFLAGS="-O1 -ftree-loop-vectorize" generates code which fails with
segmentation fault.

GCC 8.4.0 and 9.3.0 are not affected, so this is regression in GCC 10.2.0.

Original report: https://github.com/s-yata/marisa-trie/issues/35


Steps to reproduce problem:

$ git clone https://github.com/s-yata/marisa-trie
$ cd marisa-trie
$ autoreconf -ifv
$ export CC="x86_64-pc-linux-gnu-gcc-10.2.0"
$ export CXX="x86_64-pc-linux-gnu-g++-10.2.0"
$ export CFLAGS="-O1 -ftree-loop-vectorize"
$ export CXXFLAGS="-O1 -ftree-loop-vectorize"
$ ./configure
$ make
$ make check
...
PASS: base-test
PASS: io-test
PASS: vector-test
PASS: trie-test
../test-driver: line 109: 12541 Segmentation fault      "$@" > $log_file 2>&1
FAIL: marisa-test


(MARISA does not have any dependencies besides Autotools and C++ compiler, so
reproduction should be easy.)


Failing program can be run manually in this way:

$ LD_LIBRARY_PATH="$(pwd)/lib/marisa/.libs" tests/.libs/marisa-test
marisa-test.cc:13: TestEmptyTrie(): ok
marisa-test.cc:87: TestTinyTrie(): ok
Segmentation fault