[Bug rtl-optimization/7061] Access of bytes in struct parameters

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=7061

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Roger Sayle <sayle@gcc.gnu.org>:

https://gcc.gnu.org/g:64d4f27a0ce47e97867512bda7fa5683acf8a134

commit r13-1282-g64d4f27a0ce47e97867512bda7fa5683acf8a134
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Mon Jun 27 07:47:40 2022 +0100

    Implement __imag__ of float _Complex using shufps on x86_64.

    This patch is a follow-up improvement to my recent patch for
    PR rtl-optimization/7061.  That patch added the test case
    gcc.target/i386/pr7061-2.c:

    float im(float _Complex a) { return __imag__ a; }

    For which GCC on x86_64 currently generates:

            movq    %xmm0, %rax
            shrq    $32, %rax
            movd    %eax, %xmm0
            ret

    but with this patch we now generate (the same as LLVM):

            shufps  $85, %xmm0, %xmm0
            ret

    This is achieved by providing a define_insn_and_split that allows
    truncated lshiftrt:DI by 32 to be performed on either SSE or general
    regs, where if the register allocator prefers to use SSE, we split
    to a shufps_v4si, or if not, we use a regular shrq.

    2022-06-27  Roger Sayle  <roger@nextmovesoftware.com>

    gcc/ChangeLog
            PR rtl-optimization/7061
            * config/i386/i386.md (*highpartdisi2): New define_insn_and_split.

    gcc/testsuite/ChangeLog
            PR rtl-optimization/7061
            * gcc.target/i386/pr7061-2.c: Update to look for shufps.