[Bug rtl-optimization/76783] New: [7 Regression] wrong code with conditional vector assignment @ -Og

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=76783

            Bug ID: 76783
           Summary: [7 Regression] wrong code with conditional vector
                    assignment @ -Og
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu
             Build: x86_64-pc-linux-gnu

Created attachment 39444
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39444&action=edit
reduced testcase

Output:
$ x86_64-pc-linux-gnu-gcc -Og testcase.c -w
testcase.c: In function 'foo':
testcase.c:5:1: note: The ABI for passing parameters with 64-byte alignment has
changed in GCC 4.6
 foo (unsigned c, v64u128 v)
 ^~~
$ ./a.out 
Aborted

The function foo returns 'v' unchanged unconditionally:
foo:
        mov     rax, QWORD PTR [rsp+24]
        mov     rdx, QWORD PTR [rsp+32]
        ret



$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-239460-checking-yes-rtl-df-extra-nographite-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--without-cloog --without-ppl --without-isl --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-239460-checking-yes-rtl-df-extra-nographite-amd64
Thread model: posix
gcc version 7.0.0 20160815 (experimental) (GCC) 


Tested revisions:
r239460 - FAIL
6-branch r239319 - OK