On 2015-12-31 12:46:39 +0200, Martin Storsjö wrote:
> Use two separate functions, depending on whether neon is available.
should be neon or vfp
> This is set to require armv5te - it uses blx, which is only available
> since armv5t, but we don't have a separate configure item for that.
> (It also uses ldrd, which requires armv5te, but this could be avoided
> if necessary.)
This breaks running checkasm on armv4 with runtime cpu detection. It's
not very useful since it only checks if two consecutive calls of the c
variant return equal/similar results.
> ---
> Compared to x264's checkasm, this is slightly simpler since it only
> is expected to return void, i.e. no issues with handling of 64 bit return
> values vs function pointer type casting. (The assembly wrapper still tries
> to maintain the return value intact though, even though it's currently
> not used.) It also is simplified since it doesn't use separate parameter
> for indicating failures (avoiding one extra register to backup, and
> reducing the number of parameters to shift by from 2 to 1).
I think that is actually a disadvantage because it breaks type which are
naturally aligned to 8-byte. Those are assigned register pairs starting
with an even register or 8-byte aligned stack address. If we shift only
one register, that rule is broken so we need a second dummy register.
> Other than
> that, there's only been some minor touch-ups, using more of libav's
> asm.S and using #ifdef __APPLE__ instead of #if SYS_DARWIN.
>
> If all calls would include the cpuflags like declare_new_emms,
> one wouldn't need the neon vs noneon function selection at startup.
declare_new_emms doesn't include cpuflags, it specifies for which cpu
flags a emms is required. the actual (masked) cpuflags are queried by
av_get_cpu_flags(). That would work two but the startup check is more
correct since the neon/vfp checked_call variant should be always used if
the cpu supports it.
> ---
> tests/checkasm/arm/Makefile | 1 +
> tests/checkasm/arm/checkasm.S | 132
> +++++++++++++++++++++++++++++++++++++++++
> tests/checkasm/checkasm.c | 9 +++
> tests/checkasm/checkasm.h | 8 +++
> 4 files changed, 150 insertions(+)
> create mode 100644 tests/checkasm/arm/Makefile
> create mode 100644 tests/checkasm/arm/checkasm.S
>
> diff --git a/tests/checkasm/arm/Makefile b/tests/checkasm/arm/Makefile
> new file mode 100644
> index 0000000..f73da18
> --- /dev/null
> +++ b/tests/checkasm/arm/Makefile
> @@ -0,0 +1 @@
> +CHECKASMOBJS-$(HAVE_ARMV5TE) += arm/checkasm.o
> diff --git a/tests/checkasm/arm/checkasm.S b/tests/checkasm/arm/checkasm.S
> new file mode 100644
> index 0000000..d1740bc
> --- /dev/null
> +++ b/tests/checkasm/arm/checkasm.S
> @@ -0,0 +1,132 @@
> +/****************************************************************************
> + * Assembly testing and benchmarking tool
> + * Copyright (c) 2015 Martin Storsjo
> + * Copyright (c) 2015 Janne Grunau
> + *
> + * This file is part of Libav.
> + *
> + * Libav is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * Libav is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111, USA.
> +
> *****************************************************************************/
> +
> +#include "libavutil/arm/asm.S"
> +
> +const register_init
> + .quad 0x21f86d66c8ca00ce
> + .quad 0x75b6ba21077c48ad
> + .quad 0xed56bb2dcb3c7736
> + .quad 0x8bda43d3fd1a7e06
> + .quad 0xb64a9c9e5d318408
> + .quad 0xdf9a54b303f1d3a3
> + .quad 0x4a75479abd64e097
> + .quad 0x249214109d5d1c88
> +endconst
> +
> +const error_message
> + .asciz "failed to preserve register"
> +endconst
> +
> +@ max number of args used by any asm function.
> +#define MAX_ARGS 15
> +
> +#define ARG_STACK 4*(MAX_ARGS - 3)
> +
> +.macro clobbercheck variant
> +.equ pushed, 4*9
> +function checkasm_checked_call_\variant, export=1
> + push {r4-r11, lr}
> +.ifc \variant, neon
> + vpush {q4-q7}
> +.equ pushed, pushed + 16*4
> +.endif
> +
> + movrel r12, register_init
> +.ifc \variant, neon
> + vldm r12, {q4-q7}
> +.endif
> + ldm r12, {r4-r11}
> +
> + sub sp, sp, #ARG_STACK
> +.equ pos, 0
> +.rept MAX_ARGS-3
> + ldr r12, [sp, #ARG_STACK + pushed + 4 + pos]
> + str r12, [sp, #pos]
> +.equ pos, pos + 4
> +.endr
> +
> + mov r12, r0
> + mov r0, r1
> + mov r1, r2
> + mov r2, r3
> + ldr r3, [sp, #ARG_STACK + pushed]
> + blx r12
> + add sp, sp, #ARG_STACK
> +
> + push {r0, r1}
> + movrel r12, register_init
> +.ifc \variant, neon
> + vldm r12, {q0-q3}
> + veor q0, q0, q4
> + veor q1, q1, q5
> + veor q2, q2, q6
> + veor q3, q3, q7
> + vorr q0, q0, q1
> + vorr q0, q0, q2
> + vorr q0, q0, q3
> + vorr d0, d0, d1
> + vrev64.32 d1, d0
> + vorr d0, d0, d1
> + vmov.32 r3, d0[0]
> +.else
> + mov r3, #0
> +.endif
> +
> +.macro check_reg reg1, reg2=
> + ldrd r0, r1, [r12], #8
> + eor r0, r0, \reg1
> + orr r3, r3, r0
> +.ifnb \reg2
> + eor r1, r1, \reg2
> + orr r3, r3, r1
> +.endif
> +.endm
> + check_reg r4, r5
> + check_reg r6, r7
> +@ r9 is a volatile register in the ios ABI
> +#ifdef __APPLE__
> + check_reg r8
> +#else
> + check_reg r8, r9
> +#endif
> + check_reg r10, r11
> +.purgem check_reg
> +
> + cmp r3, #0
> + beq 0f
> +
> + movrel r0, error_message
> + blx X(checkasm_fail_func)
> +0:
> + pop {r0, r1}
> +.ifc \variant, neon
> + vpop {q4-q7}
> +.endif
> + pop {r4-r11, pc}
> +endfunc
> +.endm
> +
> +#if HAVE_NEON
> +clobbercheck neon
> +#endif
> +clobbercheck noneon
except for the alignment issues for types with 8-byte alignment ok
> diff --git a/tests/checkasm/checkasm.c b/tests/checkasm/checkasm.c
> index d6f8ffc..2c0bbbe 100644
> --- a/tests/checkasm/checkasm.c
> +++ b/tests/checkasm/checkasm.c
> @@ -53,6 +53,10 @@
> #define isatty(fd) 1
> #endif
>
> +#if HAVE_ARMV5TE
> +void (*checkasm_checked_call)(void *func, ...) =
> checkasm_checked_call_noneon;
> +#endif
> +
> /* List of tests to invoke */
> static const struct {
> const char *name;
> @@ -463,6 +467,11 @@ int main(int argc, char *argv[])
> {
> int i, seed, ret = 0;
>
> +#if HAVE_ARMV5TE && HAVE_NEON
> + if (av_get_cpu_flags() & AV_CPU_FLAG_NEON)
> + checkasm_checked_call = checkasm_checked_call_neon;
> +#endif
I think it would be cleaner to have this in a single ARCH_ARM block here
the easiest solution to the armv4 + runtime cpu detection would be to
return here without running any tests.
Janne
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