[Bug target/83735] New: [8 Regression] generating unaligned store to stack with vmovaps

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83735

            Bug ID: 83735
           Summary: [8 Regression] generating unaligned store to stack
                    with vmovaps
           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: x86_64-pc-linux-gnu

Created attachment 43058
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43058&action=edit
reduced testcase

Similar to PR78585 and PR83330, but this one is for different target and needs
a very small set of flags to reproduce.

This particular testcase does not fail in gcc-7, but it might be just a luck.

Output:
$ x86_64-pc-linux-gnu-gcc -O3 -mavx512bw testcase.c
$ ./a.out 
Segmentation fault

The failing instruction is:
   0x00000000004003c4 <+52>:    vmovdqu 0x200cb4(%rip),%xmm1        # 0x601080
<j>
   0x00000000004003cc <+60>:    vmovdqa 0x4ec(%rip),%ymm0        # 0x4008c0
=> 0x00000000004003d4 <+68>:    vmovaps %xmm1,-0x30(%rsp)
   0x00000000004003da <+74>:    vmovdqu 0x200cae(%rip),%xmm1        # 0x601090
<j+16>
   0x00000000004003e2 <+82>:    mov    0x200cb7(%rip),%rax        # 0x6010a0
<j+32>

(gdb) p $rsp
$1 = (void *) 0x7fffffffd678

rsp-0x30 is not correctly aligned.

$ 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-256323-checking-yes-rtl-df-extra-nographite-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/8.0.0/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-256323-checking-yes-rtl-df-extra-nographite-amd64
Thread model: posix
gcc version 8.0.0 20180107 (experimental) (GCC)