[v1] x86-64: Small improvements to dl-trampoline.S

1.  Remove sse2 instructions when using the avx512 or avx version.

2.  Fixup some format nits in how the address offsets where aligned.

3.  Use more space efficient instructions in the conditional AVX
    restoral.
        - vpcmpeqq          -> vpcmpeqb
        - cmp imm32, r; jz  -> inc r; jz

4.  Use `rep movsb` instead of `rep movsq`. The former is guranteed to
    be fast with the ERMS flags, the latter is not. The latter also
    wastes an instruction in size setup.
---
 sysdeps/x86_64/dl-trampoline.S |   4 ++
 sysdeps/x86_64/dl-trampoline.h | 113 +++++++++++++++++----------------
 2 files changed, 61 insertions(+), 56 deletions(-)

On Tue, Jun 28, 2022 at 8:26 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> 1.  Remove sse2 instructions when using the avx512 or avx version.
>
> 2.  Fixup some format nits in how the address offsets where aligned.
>
> 3.  Use more space efficient instructions in the conditional AVX
>     restoral.
>         - vpcmpeqq          -> vpcmpeqb
>         - cmp imm32, r; jz  -> inc r; jz
>
> 4.  Use `rep movsb` instead of `rep movsq`. The former is guranteed to
>     be fast with the ERMS flags, the latter is not. The latter also
>     wastes an instruction in size setup.
> ---
>  sysdeps/x86_64/dl-trampoline.S |   4 ++
>  sysdeps/x86_64/dl-trampoline.h | 113 +++++++++++++++++----------------
>  2 files changed, 61 insertions(+), 56 deletions(-)
>
> diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
> index f669805ac5..580d2b6499 100644
> --- a/sysdeps/x86_64/dl-trampoline.S
> +++ b/sysdeps/x86_64/dl-trampoline.S
> @@ -57,22 +57,26 @@
>  #define VMOVA                  vmovdqa64
>  #define VEC(i)                 zmm##i
>  #define _dl_runtime_profile    _dl_runtime_profile_avx512
> +# define SECTION(p)            p##.evex512
>  #include "dl-trampoline.h"
>  #undef _dl_runtime_profile
>  #undef VEC
>  #undef VMOVA
>  #undef VEC_SIZE
> +#undef SECTION
>
>  #if MINIMUM_X86_ISA_LEVEL <= AVX_X86_ISA_LEVEL
>  # define VEC_SIZE              32
>  # define VMOVA                 vmovdqa
>  # define VEC(i)                        ymm##i
> +# define SECTION(p)            p##.avx
>  # define _dl_runtime_profile   _dl_runtime_profile_avx
>  # include "dl-trampoline.h"
>  # undef _dl_runtime_profile
>  # undef VEC
>  # undef VMOVA
>  # undef VEC_SIZE
> +# undef SECTION
>  #endif
>
>  #if MINIMUM_X86_ISA_LEVEL < AVX_X86_ISA_LEVEL
> diff --git a/sysdeps/x86_64/dl-trampoline.h b/sysdeps/x86_64/dl-trampoline.h
> index 03bd91b3e9..3c419047ec 100644
> --- a/sysdeps/x86_64/dl-trampoline.h
> +++ b/sysdeps/x86_64/dl-trampoline.h
> @@ -16,7 +16,11 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>
> -       .text
> +#ifndef SECTION
> +# define SECTION(p)    p
> +#endif
> +
> +       .section SECTION(.text),"ax",@progbits
>  #ifdef _dl_runtime_resolve
>
>  # undef REGISTER_SAVE_AREA
> @@ -219,19 +223,19 @@ _dl_runtime_profile:
>         /* We always store the XMM registers even if AVX is available.
>            This is to provide backward binary compatibility for existing
>            audit modules.  */
> -       movaps %xmm0,              (LR_XMM_OFFSET)(%rsp)
> -       movaps %xmm1, (LR_XMM_OFFSET +   XMM_SIZE)(%rsp)
> -       movaps %xmm2, (LR_XMM_OFFSET + XMM_SIZE*2)(%rsp)
> -       movaps %xmm3, (LR_XMM_OFFSET + XMM_SIZE*3)(%rsp)
> -       movaps %xmm4, (LR_XMM_OFFSET + XMM_SIZE*4)(%rsp)
> -       movaps %xmm5, (LR_XMM_OFFSET + XMM_SIZE*5)(%rsp)
> -       movaps %xmm6, (LR_XMM_OFFSET + XMM_SIZE*6)(%rsp)
> -       movaps %xmm7, (LR_XMM_OFFSET + XMM_SIZE*7)(%rsp)
> +       VMOVA %xmm0, (LR_XMM_OFFSET + XMM_SIZE*0)(%rsp)
> +       VMOVA %xmm1, (LR_XMM_OFFSET + XMM_SIZE*1)(%rsp)
> +       VMOVA %xmm2, (LR_XMM_OFFSET + XMM_SIZE*2)(%rsp)
> +       VMOVA %xmm3, (LR_XMM_OFFSET + XMM_SIZE*3)(%rsp)
> +       VMOVA %xmm4, (LR_XMM_OFFSET + XMM_SIZE*4)(%rsp)
> +       VMOVA %xmm5, (LR_XMM_OFFSET + XMM_SIZE*5)(%rsp)
> +       VMOVA %xmm6, (LR_XMM_OFFSET + XMM_SIZE*6)(%rsp)
> +       VMOVA %xmm7, (LR_XMM_OFFSET + XMM_SIZE*7)(%rsp)
>
>  # ifdef RESTORE_AVX
>         /* This is to support AVX audit modules.  */
> -       VMOVA %VEC(0),                (LR_VECTOR_OFFSET)(%rsp)
> -       VMOVA %VEC(1), (LR_VECTOR_OFFSET +   VECTOR_SIZE)(%rsp)
> +       VMOVA %VEC(0), (LR_VECTOR_OFFSET + VECTOR_SIZE*0)(%rsp)
> +       VMOVA %VEC(1), (LR_VECTOR_OFFSET + VECTOR_SIZE*1)(%rsp)
>         VMOVA %VEC(2), (LR_VECTOR_OFFSET + VECTOR_SIZE*2)(%rsp)
>         VMOVA %VEC(3), (LR_VECTOR_OFFSET + VECTOR_SIZE*3)(%rsp)
>         VMOVA %VEC(4), (LR_VECTOR_OFFSET + VECTOR_SIZE*4)(%rsp)
> @@ -241,8 +245,8 @@ _dl_runtime_profile:
>
>         /* Save xmm0-xmm7 registers to detect if any of them are
>            changed by audit module.  */
> -       vmovdqa %xmm0,              (LR_SIZE)(%rsp)
> -       vmovdqa %xmm1, (LR_SIZE +   XMM_SIZE)(%rsp)
> +       vmovdqa %xmm0, (LR_SIZE + XMM_SIZE*0)(%rsp)
> +       vmovdqa %xmm1, (LR_SIZE + XMM_SIZE*1)(%rsp)
>         vmovdqa %xmm2, (LR_SIZE + XMM_SIZE*2)(%rsp)
>         vmovdqa %xmm3, (LR_SIZE + XMM_SIZE*3)(%rsp)
>         vmovdqa %xmm4, (LR_SIZE + XMM_SIZE*4)(%rsp)
> @@ -265,84 +269,84 @@ _dl_runtime_profile:
>         movq  LR_R8_OFFSET(%rsp), %r8
>         movq  LR_R9_OFFSET(%rsp), %r9
>
> -       movaps              (LR_XMM_OFFSET)(%rsp), %xmm0
> -       movaps   (LR_XMM_OFFSET + XMM_SIZE)(%rsp), %xmm1
> -       movaps (LR_XMM_OFFSET + XMM_SIZE*2)(%rsp), %xmm2
> -       movaps (LR_XMM_OFFSET + XMM_SIZE*3)(%rsp), %xmm3
> -       movaps (LR_XMM_OFFSET + XMM_SIZE*4)(%rsp), %xmm4
> -       movaps (LR_XMM_OFFSET + XMM_SIZE*5)(%rsp), %xmm5
> -       movaps (LR_XMM_OFFSET + XMM_SIZE*6)(%rsp), %xmm6
> -       movaps (LR_XMM_OFFSET + XMM_SIZE*7)(%rsp), %xmm7
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*0)(%rsp), %xmm0
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*1)(%rsp), %xmm1
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*2)(%rsp), %xmm2
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*3)(%rsp), %xmm3
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*4)(%rsp), %xmm4
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*5)(%rsp), %xmm5
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*6)(%rsp), %xmm6
> +       VMOVA (LR_XMM_OFFSET + XMM_SIZE*7)(%rsp), %xmm7
>
>  # ifdef RESTORE_AVX
>         /* Check if any xmm0-xmm7 registers are changed by audit
>            module.  */
> -       vpcmpeqq (LR_SIZE)(%rsp), %xmm0, %xmm8
> +       vpcmpeqb (LR_SIZE)(%rsp), %xmm0, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm0, (LR_VECTOR_OFFSET)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET)(%rsp), %VEC(0)
>         vmovdqa %xmm0, (LR_XMM_OFFSET)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE)(%rsp), %xmm1, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE)(%rsp), %xmm1, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm1, (LR_VECTOR_OFFSET + VECTOR_SIZE)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET + VECTOR_SIZE)(%rsp), %VEC(1)
>         vmovdqa %xmm1, (LR_XMM_OFFSET + XMM_SIZE)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE*2)(%rsp), %xmm2, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE*2)(%rsp), %xmm2, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm2, (LR_VECTOR_OFFSET + VECTOR_SIZE*2)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET + VECTOR_SIZE*2)(%rsp), %VEC(2)
>         vmovdqa %xmm2, (LR_XMM_OFFSET + XMM_SIZE*2)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE*3)(%rsp), %xmm3, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE*3)(%rsp), %xmm3, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm3, (LR_VECTOR_OFFSET + VECTOR_SIZE*3)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET + VECTOR_SIZE*3)(%rsp), %VEC(3)
>         vmovdqa %xmm3, (LR_XMM_OFFSET + XMM_SIZE*3)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE*4)(%rsp), %xmm4, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE*4)(%rsp), %xmm4, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm4, (LR_VECTOR_OFFSET + VECTOR_SIZE*4)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET + VECTOR_SIZE*4)(%rsp), %VEC(4)
>         vmovdqa %xmm4, (LR_XMM_OFFSET + XMM_SIZE*4)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE*5)(%rsp), %xmm5, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE*5)(%rsp), %xmm5, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm5, (LR_VECTOR_OFFSET + VECTOR_SIZE*5)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET + VECTOR_SIZE*5)(%rsp), %VEC(5)
>         vmovdqa %xmm5, (LR_XMM_OFFSET + XMM_SIZE*5)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE*6)(%rsp), %xmm6, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE*6)(%rsp), %xmm6, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm6, (LR_VECTOR_OFFSET + VECTOR_SIZE*6)(%rsp)
>         jmp 1f
>  2:     VMOVA (LR_VECTOR_OFFSET + VECTOR_SIZE*6)(%rsp), %VEC(6)
>         vmovdqa %xmm6, (LR_XMM_OFFSET + XMM_SIZE*6)(%rsp)
>
> -1:     vpcmpeqq (LR_SIZE + XMM_SIZE*7)(%rsp), %xmm7, %xmm8
> +1:     vpcmpeqb (LR_SIZE + XMM_SIZE*7)(%rsp), %xmm7, %xmm8
>         vpmovmskb %xmm8, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         je 2f
>         vmovdqa %xmm7, (LR_VECTOR_OFFSET + VECTOR_SIZE*7)(%rsp)
>         jmp 1f
> @@ -352,8 +356,8 @@ _dl_runtime_profile:
>  1:
>  # endif
>
> -       mov  16(%rbx), %R10_LP  # Anything in framesize?
> -       test %R10_LP, %R10_LP
> +       mov  16(%rbx), %RCX_LP  # Anything in framesize?
> +       test %RCX_LP, %RCX_LP
>         jns 3f
>
>         /* There's nothing in the frame size, so there
> @@ -385,14 +389,11 @@ _dl_runtime_profile:
>            returned from _dl_profile_fixup */
>
>         lea LR_RSP_OFFSET(%rbx), %RSI_LP # stack
> -       add $8, %R10_LP
> -       and $-16, %R10_LP
> -       mov %R10_LP, %RCX_LP
> -       sub %R10_LP, %RSP_LP
> +       add $8, %RCX_LP
> +       and $-16, %RCX_LP
> +       sub %RCX_LP, %RSP_LP
>         mov %RSP_LP, %RDI_LP
> -       shr $3, %RCX_LP
> -       rep
> -       movsq
> +       rep movsb
>
>         movq 24(%rdi), %rcx     # Get back register content.
>         movq 32(%rdi), %rsi
> @@ -428,8 +429,8 @@ _dl_runtime_profile:
>         movq %rax, LRV_RAX_OFFSET(%rcx)
>         movq %rdx, LRV_RDX_OFFSET(%rcx)
>
> -       movaps %xmm0, LRV_XMM0_OFFSET(%rcx)
> -       movaps %xmm1, LRV_XMM1_OFFSET(%rcx)
> +       VMOVA %xmm0, LRV_XMM0_OFFSET(%rcx)
> +       VMOVA %xmm1, LRV_XMM1_OFFSET(%rcx)
>
>  # ifdef RESTORE_AVX
>         /* This is to support AVX audit modules.  */
> @@ -438,8 +439,8 @@ _dl_runtime_profile:
>
>         /* Save xmm0/xmm1 registers to detect if they are changed
>            by audit module.  */
> -       vmovdqa %xmm0,            (LRV_SIZE)(%rcx)
> -       vmovdqa %xmm1, (LRV_SIZE + XMM_SIZE)(%rcx)
> +       vmovdqa %xmm0, (LRV_SIZE + XMM_SIZE*0)(%rcx)
> +       vmovdqa %xmm1, (LRV_SIZE + XMM_SIZE*1)(%rcx)
>  # endif
>
>         fstpt LRV_ST0_OFFSET(%rcx)
> @@ -454,20 +455,20 @@ _dl_runtime_profile:
>         movq LRV_RAX_OFFSET(%rsp), %rax
>         movq LRV_RDX_OFFSET(%rsp), %rdx
>
> -       movaps LRV_XMM0_OFFSET(%rsp), %xmm0
> -       movaps LRV_XMM1_OFFSET(%rsp), %xmm1
> +       VMOVA LRV_XMM0_OFFSET(%rsp), %xmm0
> +       VMOVA LRV_XMM1_OFFSET(%rsp), %xmm1
>
>  # ifdef RESTORE_AVX
>         /* Check if xmm0/xmm1 registers are changed by audit module.  */
> -       vpcmpeqq (LRV_SIZE)(%rsp), %xmm0, %xmm2
> +       vpcmpeqb (LRV_SIZE)(%rsp), %xmm0, %xmm2
>         vpmovmskb %xmm2, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         jne 1f
>         VMOVA LRV_VECTOR0_OFFSET(%rsp), %VEC(0)
>
> -1:     vpcmpeqq (LRV_SIZE + XMM_SIZE)(%rsp), %xmm1, %xmm2
> +1:     vpcmpeqb (LRV_SIZE + XMM_SIZE)(%rsp), %xmm1, %xmm2
>         vpmovmskb %xmm2, %esi
> -       cmpl $0xffff, %esi
> +       incw %si
>         jne 1f
>         VMOVA LRV_VECTOR1_OFFSET(%rsp), %VEC(1)
>
> --
> 2.34.1
>

LGTM.

Thanks.