[PATCH] x86: Avoid stack realignment when copying data with SSE register

Uros Bizjak ubizjak@gmail.com
Wed Aug 4 18:40:57 GMT 2021


On Wed, Aug 4, 2021 at 3:20 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> To avoid stack realignment, call ix86_gen_scratch_sse_rtx to get a
> scratch SSE register to copy data with with SSE register from one
> memory location to another.
>
> gcc/
>
>         PR target/101772
>         * config/i386/i386-expand.c (ix86_expand_vector_move): Call
>         ix86_gen_scratch_sse_rtx to get a scratch SSE register to copy
>         data with SSE register from one memory location to another.
>
> gcc/testsuite/
>
>         PR target/101772
>         * gcc.target/i386/eh_return-2.c: New test.

LGTM.

Thanks,
Uros.

> ---
>  gcc/config/i386/i386-expand.c               |  6 +++++-
>  gcc/testsuite/gcc.target/i386/eh_return-2.c | 16 ++++++++++++++++
>  2 files changed, 21 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/eh_return-2.c
>
> diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c
> index 1d469bf7221..bd21efa9530 100644
> --- a/gcc/config/i386/i386-expand.c
> +++ b/gcc/config/i386/i386-expand.c
> @@ -613,7 +613,11 @@ ix86_expand_vector_move (machine_mode mode, rtx operands[])
>          arguments in memory.  */
>        if (!register_operand (op0, mode)
>           && !register_operand (op1, mode))
> -       op1 = force_reg (mode, op1);
> +       {
> +         rtx scratch = ix86_gen_scratch_sse_rtx (mode);
> +         emit_move_insn (scratch, op1);
> +         op1 = scratch;
> +       }
>
>        tmp[0] = op0; tmp[1] = op1;
>        ix86_expand_vector_move_misalign (mode, tmp);
> diff --git a/gcc/testsuite/gcc.target/i386/eh_return-2.c b/gcc/testsuite/gcc.target/i386/eh_return-2.c
> new file mode 100644
> index 00000000000..f23f4492dac
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/eh_return-2.c
> @@ -0,0 +1,16 @@
> +/* PR target/101772  */
> +/* { dg-do compile } */
> +/* { dg-additional-options "-O0 -march=x86-64 -mstackrealign" } */
> +
> +struct _Unwind_Context _Unwind_Resume_or_Rethrow_this_context;
> +
> +void offset (int);
> +
> +struct _Unwind_Context {
> +  void *reg[7];
> +} _Unwind_Resume_or_Rethrow() {
> +  struct _Unwind_Context cur_contextcur_context =
> +      _Unwind_Resume_or_Rethrow_this_context;
> +  offset(0);
> +  __builtin_eh_return ((long) offset, 0);
> +}
> --
> 2.31.1
>


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