[Bug target/84169] New: [8 Regression] wrong code with u128 multiplication result at aarch64 -O

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84169

            Bug ID: 84169
           Summary: [8 Regression] wrong code with u128 multiplication
                    result at aarch64 -O
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: aarch64-unknown-linux-gnu

Created attachment 43319
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43319&action=edit
reduced testcase

Output:
$ aarch64-unknown-linux-gnu-gcc testcase.c -static -O
$ ./a.out 
qemu: uncaught target signal 6 (Aborted) - core dumped
Aborted

The most-significant 64bit are zeros, but should be ones.

$ aarch64-unknown-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-aarch64/bin/aarch64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-257303-checking-yes-rtl-df-extra-aarch64/bin/../libexec/gcc/aarch64-unknown-linux-gnu/8.0.1/lto-wrapper
Target: aarch64-unknown-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl
--with-sysroot=/usr/aarch64-unknown-linux-gnu --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=aarch64-unknown-linux-gnu
--with-ld=/usr/bin/aarch64-unknown-linux-gnu-ld
--with-as=/usr/bin/aarch64-unknown-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-257303-checking-yes-rtl-df-extra-aarch64
Thread model: posix
gcc version 8.0.1 20180201 (experimental) (GCC)