[Bug target/54412] Request for 32-byte stack alignment with -mavx on Windows

[rcopley at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54412

--- Comment #11 from R Copley <rcopley at gmail dot com> ---
On 20 September 2014 07:08, roland at rschulz dot eu
<gcc-bugzilla@gcc.gnu.org> wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54412
>
> --- Comment #10 from Roland Schulz <roland at rschulz dot eu> ---
> Created attachment 33520
>   --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33520&action=edit
> Slightly modified testcase
>
> This slightly modified testcase in which the return value isn't stored, still
> segfaults for me. With the 32bit mingw64 binary ((i686-win32-dwarf-rev1, Built
> by MinGW-W64 project) 4.9.1) it is OK, but with the 64bit binary
> ((x86_64-win32-seh-rev1, Built by MinGW-W64 project) 4.9.1) it segfaults.

Confirmed (with the same compiler, in the mingw-builds toolchain). I
compiled your testcase with command "gcc -O0 -g -ggdb -m64 -mavx
bug.c". It segfaults on the instruction marked "=>" below.

(gdb) disassemble /m
Dump of assembler code for function f:
6       {
   0x00000000004014f0 <+0>:     push   %rbp
   0x00000000004014f1 <+1>:     mov    %rsp,%rbp
   0x00000000004014f4 <+4>:     mov    %rcx,0x10(%rbp)
   0x00000000004014f8 <+8>:     sub    $0x40,%rsp
   0x00000000004014fc <+12>:    mov    %rsp,%rax
   0x00000000004014ff <+15>:    add    $0x1f,%rax
   0x0000000000401503 <+19>:    shr    $0x5,%rax
   0x0000000000401507 <+23>:    shl    $0x5,%rax

7         v4d x __attribute__ ((aligned (32))) = { 1.0, 2.0, 3.0, 4.0, };
   0x000000000040150b <+27>:    vmovapd 0x2aed(%rip),%ymm0        # 0x404000
   0x0000000000401513 <+35>:    vmovapd %ymm0,(%rax)

8         return x;
   0x0000000000401517 <+39>:    mov    0x10(%rbp),%rdx
   0x000000000040151b <+43>:    vmovapd (%rax),%ymm0
=> 0x000000000040151f <+47>:    vmovapd %ymm0,(%rdx)

9       }
   0x0000000000401523 <+51>:    mov    0x10(%rbp),%rax
   0x0000000000401527 <+55>:    mov    %rbp,%rsp
   0x000000000040152a <+58>:    pop    %rbp
   0x000000000040152b <+59>:    retq

End of assembler dump.
(gdb) print $rdx % 32
$1 = 16