[Bug rtl-optimization/68670] New: [4.9/5/6 Regression] gcc.c-torture/execute/pr68376-2.c FAILs with -ftracer

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68670

            Bug ID: 68670
           Summary: [4.9/5/6 Regression] gcc.c-torture/execute/pr68376-2.c
                    FAILs with -ftracer
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---

Created attachment 36894
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36894&action=edit
reduced testcase

As mentioned in PR68376#c8, the testcase is failing with -ftracer.

On the 5-branch, -O2 -ftracer is needed; -O -tracer is enough on other
branches.

armv7, aarch64, powerpc, x86_64 is affected; powerpc64 doesn't seem to fail.

Dumps up to .optimized look fine, it still seems to be an RTL optimizer bug.

Output:
$ $CC -O2 -ftracer testcase.c
$ ./a.out
Aborted


$ gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-231194-checking-yes-rtl-df-nographite/bin/../libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-checking=yes,rtl,df --without-cloog --without-ppl --without-isl
--disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-231194-checking-yes-rtl-df-nographite
Thread model: posix
gcc version 6.0.0 20151202 (experimental) (GCC)