On Mon, Jul 31, 2017 at 1:24 PM, Daniel Santos <daniel.san...@pobox.com> wrote:
> The -mcall-ms2sysv-xlogues project added the boolean fields
> call_ms2sysv_pad_in and call_ms2sysv_pad_out to struct machine_function
> to track rather or not an additional 8 bytes of padding was needed for
> stack alignment prior to and after the stub save area. This design was
> based upon the faulty assumption the function body would not require a
> stack alignment greater than 16 bytes. This continues to work well for
> managing padding prior to the stub save area, but will not work for the
> outgoing alignment.
>
> Rather than changing machine_function::call_ms2sysv_pad_out to a larger
> type, this patch removes it, thus transferring responsibility for stack
> alignment following the stub save area from class xlogue_layout to the
> body of ix86_compute_frame_layout. Since the 64-bit va_arg register
> save area is always a multiple of 16-bytes in size (176 for System V ABI
> and 96 for Microsoft ABI), the ROUND_UP calculation for the stack offset
> at the start of the function body (frame.frame_pointer_offset) will
> assure there is enough room for any padding needed to keep the save area
> for SSE va_args 16-byte aligned, so no modification is needed for that
> calculation.
>
> Signed-off-by: Daniel Santos <daniel.san...@pobox.com>
LGTM.
OK for mainline.
Thanks,
Uros.
> ---
> gcc/config/i386/i386.c | 18 ++++--------------
> gcc/config/i386/i386.h | 8 ++------
> 2 files changed, 6 insertions(+), 20 deletions(-)
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 47c5608c3cd..e2e9546a27c 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -2491,9 +2491,7 @@ public:
> unsigned last_reg = m->call_ms2sysv_extra_regs + MIN_REGS - 1;
>
> gcc_assert (m->call_ms2sysv_extra_regs <= MAX_EXTRA_REGS);
> - return m_regs[last_reg].offset
> - + (m->call_ms2sysv_pad_out ? 8 : 0)
> - + STUB_INDEX_OFFSET;
> + return m_regs[last_reg].offset + STUB_INDEX_OFFSET;
> }
>
> /* Returns the offset for the base pointer used by the stub. */
> @@ -12849,13 +12847,12 @@ ix86_compute_frame_layout (void)
> {
> unsigned count = xlogue_layout::count_stub_managed_regs ();
> m->call_ms2sysv_extra_regs = count - xlogue_layout::MIN_REGS;
> + m->call_ms2sysv_pad_in = 0;
> }
> }
>
> frame->nregs = ix86_nsaved_regs ();
> frame->nsseregs = ix86_nsaved_sseregs ();
> - m->call_ms2sysv_pad_in = 0;
> - m->call_ms2sysv_pad_out = 0;
>
> /* 64-bit MS ABI seem to require stack alignment to be always 16,
> except for function prologues, leaf functions and when the defult
> @@ -12957,15 +12954,7 @@ ix86_compute_frame_layout (void)
> gcc_assert (!frame->nsseregs);
>
> m->call_ms2sysv_pad_in = !!(offset & UNITS_PER_WORD);
> -
> - /* Select an appropriate layout for incoming stack offset. */
> - const struct xlogue_layout &xlogue = xlogue_layout::get_instance ();
> -
> - if ((offset + xlogue.get_stack_space_used ()) & UNITS_PER_WORD)
> - m->call_ms2sysv_pad_out = 1;
> -
> - offset += xlogue.get_stack_space_used ();
> - gcc_assert (!(offset & 0xf));
> + offset += xlogue_layout::get_instance ().get_stack_space_used ();
> }
>
> /* Align and set SSE register save area. */
> @@ -12993,6 +12982,7 @@ ix86_compute_frame_layout (void)
>
> /* Align start of frame for local function. */
> if (stack_realign_fp
> + || m->call_ms2sysv
> || offset != frame->sse_reg_save_offset
> || size != 0
> || !crtl->is_leaf
> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
> index 1648bdf1556..b08e45f68d4 100644
> --- a/gcc/config/i386/i386.h
> +++ b/gcc/config/i386/i386.h
> @@ -2646,17 +2646,13 @@ struct GTY(()) machine_function {
> BOOL_BITFIELD arg_reg_available : 1;
>
> /* If true, we're out-of-lining reg save/restore for regs clobbered
> - by ms_abi functions calling a sysv function. */
> + by 64-bit ms_abi functions calling a sysv_abi function. */
> BOOL_BITFIELD call_ms2sysv : 1;
>
> /* If true, the incoming 16-byte aligned stack has an offset (of 8) and
> - needs padding. */
> + needs padding prior to out-of-line stub save/restore area. */
> BOOL_BITFIELD call_ms2sysv_pad_in : 1;
>
> - /* If true, the size of the stub save area plus inline int reg saves will
> - result in an 8 byte offset, so needs padding. */
> - BOOL_BITFIELD call_ms2sysv_pad_out : 1;
> -
> /* This is the number of extra registers saved by stub (valid range is
> 0-6). Each additional register is only saved/restored by the stubs
> if all successive ones are. (Will always be zero when using a hard
> --
> 2.13.3
>
