Skip to content

F
ffmpeg.wasm-core
Commit a812b599 authored by Roland Scheidegger's avatar Roland Scheidegger Committed by Michael Niedermayer
Browse files
Options

h264: assembly version of get_cabac for x86_64 with PIC (v4) 

This adds a hand-optimized assembly version for get_cabac much like the
existing one, but it works if the table offsets are RIP-relative.
Compared to the non-RIP-relative version this adds 2 lea instructions
and it needs one extra register.
There is a surprisingly large performance improvement over the c version (more
so than the generated assembly seems to suggest) just in get_cabac, I measured
roughly 40% faster for get_cabac on a K8. However, overall the difference is
not that big, I measured roughly 5% on a test clip on a K8 and a Core2.
Hopefully it still compiles on x86 32bit...
v2: incorporated feedback from Loren Merritt to avoid rip-relative movs
for every table, and got rid of unnecessary @GOTPCREL.
v3: apply similar fixes to the the decode_significance functions, and use
same macro arguments for non-pic case.
v4: prettify inline asm arguments, add a non-fast-cmov version (as I expect
the c code to be faster otherwise since both cmov and sbb suck hard on a
Prescott, even can't construct the mask with a 64bit shift as that's just as
terrible - it's quite difficult to find usable instructions on that chip...).
This is tested to work but not on a P4, in theory it _should_ be fast there.
Signed-off-by: 's avatarMichael Niedermayer <michaelni@gmx.at>
parent 3194ab78
Hide whitespace changes
Inline Side-by-side
Showing with 125 additions and 25 deletions
libavcodec/h264_cabac.c
View file @ a812b599
......@@ -1659,7 +1659,7 @@ decode_cabac_residual_internal(H264Context *h, DCTELEM *block,
index[coeff_count++] = last;\
}
const uint8_t *sig_off = significant_coeff_flag_offset_8x8[MB_FIELD];
#if ARCH_X86 && HAVE_7REGS && !defined(BROKEN_RELOCATIONS)
#if ARCH_X86 && HAVE_7REGS
coeff_count= decode_significance_8x8_x86(CC, significant_coeff_ctx_base, index,
last_coeff_ctx_base, sig_off);
} else {
......
libavcodec/x86/cabac.h
View file @ a812b599
......@@ -24,8 +24,71 @@
#include "libavcodec/cabac.h"
#include "libavutil/attributes.h"
#include "libavutil/x86_cpu.h"
#include "libavutil/internal.h"
#include "config.h"
#ifdef BROKEN_RELOCATIONS
#define RIP_ARG , "r"(rip)
#if HAVE_FAST_CMOV
#define BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
"cmp "low" , "tmp" \n\t"\
"cmova %%ecx , "range" \n\t"\
"sbb %%rcx , %%rcx \n\t"\
"and %%ecx , "tmp" \n\t"\
"xor %%rcx , "retq" \n\t"\
"sub "tmp" , "low" \n\t"
#else /* HAVE_FAST_CMOV */
#define BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
/* P4 Prescott has crappy cmov,sbb,64bit shift so avoid them */ \
"sub "low" , "tmp" \n\t"\
"sar $31 , "tmp" \n\t"\
"sub %%ecx , "range" \n\t"\
"and "tmp" , "range" \n\t"\
"add %%ecx , "range" \n\t"\
"shl $17 , %%ecx \n\t"\
"and "tmp" , %%ecx \n\t"\
"sub %%ecx , "low" \n\t"\
"xor "tmp" , "ret" \n\t"\
"movslq "ret" , "retq" \n\t"
#endif /* HAVE_FAST_CMOV */
#define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, rip) \
"movzbl "statep" , "ret" \n\t"\
"mov "range" , "tmp" \n\t"\
"and $0xC0 , "range" \n\t"\
"lea ("ret", "range", 2), %%ecx \n\t"\
"movzbl ff_h264_lps_range-1b("rip", %%rcx), "range" \n\t"\
"sub "range" , "tmp" \n\t"\
"mov "tmp" , %%ecx \n\t"\
"shl $17 , "tmp" \n\t"\
BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
"movzbl ff_h264_norm_shift-1b("rip", "rangeq"), %%ecx \n\t"\
"shl %%cl , "range" \n\t"\
"movzbl ff_h264_mlps_state-1b+128("rip", "retq"), "tmp" \n\t"\
"shl %%cl , "low" \n\t"\
"mov "tmpbyte" , "statep" \n\t"\
"test "lowword" , "lowword" \n\t"\
" jnz 2f \n\t"\
"mov "byte" , %%"REG_c" \n\t"\
"add"OPSIZE" $2 , "byte" \n\t"\
"movzwl (%%"REG_c") , "tmp" \n\t"\
"lea -1("low") , %%ecx \n\t"\
"xor "low" , %%ecx \n\t"\
"shr $15 , %%ecx \n\t"\
"bswap "tmp" \n\t"\
"shr $15 , "tmp" \n\t"\
"movzbl ff_h264_norm_shift-1b("rip", %%rcx), %%ecx \n\t"\
"sub $0xFFFF , "tmp" \n\t"\
"neg %%ecx \n\t"\
"add $7 , %%ecx \n\t"\
"shl %%cl , "tmp" \n\t"\
"add "tmp" , "low" \n\t"\
"2: \n\t"
#else /* BROKEN_RELOCATIONS */
#define RIP_ARG
#if HAVE_FAST_CMOV
#define BRANCHLESS_GET_CABAC_UPDATE(ret, statep, low, range, tmp)\
"mov "tmp" , %%ecx \n\t"\
......@@ -51,7 +114,7 @@
"xor "tmp" , "ret" \n\t"
#endif /* HAVE_FAST_CMOV */
#define BRANCHLESS_GET_CABAC(ret, statep, low, lowword, range, tmp, tmpbyte, byte, end) \
#define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, rip) \
"movzbl "statep" , "ret" \n\t"\
"mov "range" , "tmp" \n\t"\
"and $0xC0 , "range" \n\t"\
......@@ -81,28 +144,39 @@
"add "tmp" , "low" \n\t"\
"2: \n\t"
#endif /* BROKEN_RELOCATIONS */
#if HAVE_7REGS && !defined(BROKEN_RELOCATIONS) && !(defined(__i386) && defined(__clang__) && (__clang_major__<2 || (__clang_major__==2 && __clang_minor__<10)))\
&& !(defined(__i386) && !defined(__clang__) && defined(__llvm__) && __GNUC__==4 && __GNUC_MINOR__==2 && __GNUC_PATCHLEVEL__<=1)
#if HAVE_7REGS && !(defined(__i386) && defined(__clang__) && (__clang_major__<2 || (__clang_major__==2 && __clang_minor__<10)))\
&& !(defined(__i386) && !defined(__clang__) && defined(__llvm__) && __GNUC__==4 && __GNUC_MINOR__==2 && __GNUC_PATCHLEVEL__<=1)
#define get_cabac_inline get_cabac_inline_x86
static av_always_inline int get_cabac_inline_x86(CABACContext *c,
uint8_t *const state)
{
int bit, tmp;
#ifdef BROKEN_RELOCATIONS
int *rip;
__asm__ volatile(
"1: \n\t"
"lea 1b(%%rip), %0 \n\t"
: "=&r"(rip)
);
#endif
__asm__ volatile(
BRANCHLESS_GET_CABAC("%0", "(%4)", "%1", "%w1",
"%2", "%3", "%b3",
"%a6(%5)", "%a7(%5)")
BRANCHLESS_GET_CABAC("%0", "%q0", "(%4)", "%1", "%w1",
"%2", "%q2", "%3", "%b3",
"%a6(%5)", "%a7(%5)", "%8")
: "=&r"(bit), "+&r"(c->low), "+&r"(c->range), "=&q"(tmp)
: "r"(state), "r"(c),
"i"(offsetof(CABACContext, bytestream)),
"i"(offsetof(CABACContext, bytestream_end))
"i"(offsetof(CABACContext, bytestream_end)) RIP_ARG
: "%"REG_c, "memory"
);
return bit & 1;
}
#endif /* HAVE_7REGS && !defined(BROKEN_RELOCATIONS) */
#endif /* HAVE_7REGS */
#define get_cabac_bypass_sign get_cabac_bypass_sign_x86
static av_always_inline int get_cabac_bypass_sign_x86(CABACContext *c, int val)
......
libavcodec/x86/h264_i386.h
View file @ a812b599
......@@ -36,7 +36,7 @@
//FIXME use some macros to avoid duplicating get_cabac (cannot be done yet
//as that would make optimization work hard)
#if HAVE_7REGS && !defined(BROKEN_RELOCATIONS)
#if HAVE_7REGS
static int decode_significance_x86(CABACContext *c, int max_coeff,
uint8_t *significant_coeff_ctx_base,
int *index, x86_reg last_off){
......@@ -45,20 +45,31 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
int minusindex= 4-(intptr_t)index;
int bit;
x86_reg coeff_count;
#ifdef BROKEN_RELOCATIONS
int *rip;
__asm__ volatile(
"1: \n\t"
"lea 1b(%%rip), %0 \n\t"
: "=&r"(rip)
);
#endif
__asm__ volatile(
"3: \n\t"
BRANCHLESS_GET_CABAC("%4", "(%1)", "%3", "%w3",
"%5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)", "%13")
"test $1, %4 \n\t"
" jz 4f \n\t"
"add %10, %1 \n\t"
BRANCHLESS_GET_CABAC("%4", "(%1)", "%3", "%w3",
"%5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)", "%13")
"sub %10, %1 \n\t"
"mov %2, %0 \n\t"
......@@ -86,7 +97,7 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
"+&r"(c->low), "=&r"(bit), "+&r"(c->range)
: "r"(c), "m"(minusstart), "m"(end), "m"(minusindex), "m"(last_off),
"i"(offsetof(CABACContext, bytestream)),
"i"(offsetof(CABACContext, bytestream_end))
"i"(offsetof(CABACContext, bytestream_end)) RIP_ARG
: "%"REG_c, "memory"
);
return coeff_count;
......@@ -100,6 +111,17 @@ static int decode_significance_8x8_x86(CABACContext *c,
x86_reg coeff_count;
x86_reg last=0;
x86_reg state;
#ifdef BROKEN_RELOCATIONS
int *rip;
__asm__ volatile(
"1: \n\t"
"lea 1b(%%rip), %0 \n\t"
: "=&r"(rip)
);
#endif
__asm__ volatile(
"mov %1, %6 \n\t"
"3: \n\t"
......@@ -108,20 +130,24 @@ static int decode_significance_8x8_x86(CABACContext *c,
"movzbl (%0, %6), %k6 \n\t"
"add %9, %6 \n\t"
BRANCHLESS_GET_CABAC("%4", "(%6)", "%3", "%w3",
"%5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)", "%14")
"mov %1, %k6 \n\t"
"test $1, %4 \n\t"
" jz 4f \n\t"
"movzbl "MANGLE(last_coeff_flag_offset_8x8)"(%k6), %k6\n\t"
#ifdef BROKEN_RELOCATIONS
"movzbl last_coeff_flag_offset_8x8-1b(%14, %q6), %k6\n\t"
#else
"movzbl last_coeff_flag_offset_8x8(%k6), %k6\n\t"
#endif
"add %11, %6 \n\t"
BRANCHLESS_GET_CABAC("%4", "(%6)", "%3", "%w3",
"%5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)", "%14")
"mov %2, %0 \n\t"
"mov %1, %k6 \n\t"
......@@ -147,7 +173,7 @@ static int decode_significance_8x8_x86(CABACContext *c,
: "r"(c), "m"(minusindex), "m"(significant_coeff_ctx_base),
"m"(sig_off), "m"(last_coeff_ctx_base),
"i"(offsetof(CABACContext, bytestream)),
"i"(offsetof(CABACContext, bytestream_end))
"i"(offsetof(CABACContext, bytestream_end)) RIP_ARG
: "%"REG_c, "memory"
);
return coeff_count;
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment