[Bug target/59405] New: Incorrect FP<->MMX transition during call/ret

[kirill.yukhin at intel dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59405

            Bug ID: 59405
           Summary: Incorrect FP<->MMX transition during call/ret
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kirill.yukhin at intel dot com

Hello,
Attached test reproduces the error:
  $ gcc -m32 -mmmx 1.c
  $ ./a.out
  Aborted (core dumped)

Disassembly of the foo is:
foo32x2_be:
.LFB0:
        pushl   %ebp    # 22    *pushsi2        [length = 1]
        movl    %esp, %ebp      # 23    *movsi_internal/1       [length = 2]
        subl    $16, %esp       # 24    pro_epilogue_adjust_stack_si_add/1     
[length = 3]
        movq    %mm0, -8(%ebp)  # 3     *movv2sf_internal/9     [length = 4]
        movl    -4(%ebp), %eax  # 7     *movsf_internal/4       [length = 3]
        movl    %eax, -12(%ebp) # 14    *movsf_internal/5       [length = 3]
        flds    -12(%ebp)       # 21    *movsf_internal/1       [length = 3]
        leave   # 27    leave   [length = 1]
        ret     # 28    simple_return_internal  [length = 1]

We're passing v2sf vector using MMX register, which aliased to x87 stack.
Then we're trying to load FP to it, which leds to NaN.

As far as I understand, we need `emms' instruction between last MMX use and
before first x87 use.

Reproduces everywhere, up to 4.7.2 (may be earlier, I have no such).