On Tue, Feb 1, 2022 at 2:56 AM H.J. Lu via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Before MPX was removed, "%!" was mapped to
>
> case '!':
> if (ix86_bnd_prefixed_insn_p (current_output_insn))
> fputs ("bnd ", file);
> return;
>
> After CET was added and MPX was removed, "%!" was mapped to
>
> case '!':
> if (ix86_notrack_prefixed_insn_p (current_output_insn))
> fputs ("notrack ", file);
> return;
>
> ix86_notrack_prefixed_insn_p always returns false on ret since the
> notrack prefix is only for indirect branches. Remove the unused "%!"
> before ret.
The patch LGTM.
BTW This patch seems to be independent of straight-line-speculation mitigation.
>
> PR target/103307
> * config/i386/i386.c (ix86_code_end): Remove "%!" before ret.
> (ix86_output_function_return): Likewise.
> * config/i386/i386.md (simple_return_pop_internal): Likewise.
>
> (cherry picked from commit 8e410de43ce039bbe08f1e0195e3b6ec24f68cae)
> ---
> gcc/config/i386/i386.c | 4 ++--
> gcc/config/i386/i386.md | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 8e8c8beb366..4ba1a218ee6 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -6000,7 +6000,7 @@ ix86_code_end (void)
> xops[0] = gen_rtx_REG (Pmode, regno);
> xops[1] = gen_rtx_MEM (Pmode, stack_pointer_rtx);
> output_asm_insn ("mov%z0\t{%1, %0|%0, %1}", xops);
> - output_asm_insn ("%!ret", NULL);
> + fputs ("\tret\n", asm_out_file);
> final_end_function ();
> init_insn_lengths ();
> free_after_compilation (cfun);
> @@ -16027,7 +16027,7 @@ ix86_output_function_return (bool long_p)
> }
>
> if (!long_p)
> - return "%!ret";
> + return "ret";
>
> return "rep%; ret";
> }
> diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
> index db9dbf384ad..1aff2ac2a82 100644
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -13912,7 +13912,7 @@ (define_insn_and_split "simple_return_pop_internal"
> [(simple_return)
> (use (match_operand:SI 0 "const_int_operand"))]
> "reload_completed"
> - "%!ret\t%0"
> + "ret\t%0"
> "&& cfun->machine->function_return_type != indirect_branch_keep"
> [(const_int 0)]
> "ix86_split_simple_return_pop_internal (operands[0]); DONE;"
> --
> 2.34.1
>
--
BR,
Hongtao
