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h264: new assembly version of get_cabac for x86_64 with PIC

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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. get_cabac() gets about 40% faster, for
an overall speedup of about 5%.

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>
pull/30/merge
Roland Scheidegger 13 years ago committed by Ronald S. Bultje
parent 14e9ffc1e4
commit 9b9df1cdff
3 changed files with 121 additions and 24 deletions
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  1. 2
      libavcodec/h264_cabac.c
  2. 90
      libavcodec/x86/cabac.h
  3. 53
      libavcodec/x86/h264_i386.h

2
libavcodec/h264_cabac.c
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@ -1652,7 +1652,7 @@ 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 {

90
libavcodec/x86/cabac.h
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@ -27,6 +27,71 @@
#include "libavutil/internal.h"
#include "config.h"
#ifdef BROKEN_RELOCATIONS
#define TABLES_ARG , "r"(tables)
#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, norm_off, lps_off, mlps_off, tables) \
"movzbl "statep" , "ret" \n\t"\
"mov "range" , "tmp" \n\t"\
"and $0xC0 , "range" \n\t"\
"lea ("ret", "range", 2), %%ecx \n\t"\
"movzbl "lps_off"("tables", %%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 "norm_off"("tables", "rangeq"), %%ecx \n\t"\
"shl %%cl , "range" \n\t"\
"movzbl "mlps_off"+128("tables", "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"\
"cmp "end" , %%"REG_c" \n\t"\
"jge 1f \n\t"\
"add"OPSIZE" $2 , "byte" \n\t"\
"1: \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 "norm_off"("tables", %%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 TABLES_ARG
#if HAVE_FAST_CMOV
#define BRANCHLESS_GET_CABAC_UPDATE(ret, low, range, tmp)\
"mov "tmp" , %%ecx \n\t"\
@ -52,7 +117,7 @@
"xor "tmp" , "ret" \n\t"
#endif /* HAVE_FAST_CMOV */
#define BRANCHLESS_GET_CABAC(ret, statep, low, lowword, range, tmp, tmpbyte, byte, end, norm_off, lps_off, mlps_off) \
#define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, norm_off, lps_off, mlps_off, tables) \
"movzbl "statep" , "ret" \n\t"\
"mov "range" , "tmp" \n\t"\
"and $0xC0 , "range" \n\t"\
@ -85,29 +150,40 @@
"add "tmp" , "low" \n\t"\
"2: \n\t"
#if HAVE_7REGS && !defined(BROKEN_RELOCATIONS)
#endif /* BROKEN_RELOCATIONS */
#if HAVE_7REGS
#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
void *tables;
__asm__ volatile(
"lea "MANGLE(ff_h264_cabac_tables)", %0 \n\t"
: "=&r"(tables)
);
#endif
__asm__ volatile(
BRANCHLESS_GET_CABAC("%0", "(%4)", "%1", "%w1",
"%2", "%3", "%b3",
"%a6(%5)", "%a7(%5)", "%a8", "%a9", "%a10")
BRANCHLESS_GET_CABAC("%0", "%q0", "(%4)", "%1", "%w1",
"%2", "%q2", "%3", "%b3",
"%a6(%5)", "%a7(%5)", "%a8", "%a9", "%a10", "%11")
: "=&r"(bit), "+&r"(c->low), "+&r"(c->range), "=&q"(tmp)
: "r"(state), "r"(c),
"i"(offsetof(CABACContext, bytestream)),
"i"(offsetof(CABACContext, bytestream_end)),
"i"(H264_NORM_SHIFT_OFFSET),
"i"(H264_LPS_RANGE_OFFSET),
"i"(H264_MLPS_STATE_OFFSET)
"i"(H264_MLPS_STATE_OFFSET) TABLES_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)

53
libavcodec/x86/h264_i386.h
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@ -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){
@ -46,20 +46,29 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
int bit;
x86_reg coeff_count;
#ifdef BROKEN_RELOCATIONS
void *tables;
__asm__ volatile(
"lea "MANGLE(ff_h264_cabac_tables)", %0 \n\t"
: "=&r"(tables)
);
#endif
__asm__ volatile(
"3: \n\t"
BRANCHLESS_GET_CABAC("%4", "(%1)", "%3", "%w3",
"%5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)", "%a13", "%a14", "%a15")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)", "%a13", "%a14", "%a15", "%16")
"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)", "%a13", "%a14", "%a15")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a11(%6)", "%a12(%6)", "%a13", "%a14", "%a15", "%16")
"sub %10, %1 \n\t"
"mov %2, %0 \n\t"
@ -90,7 +99,7 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
"i"(offsetof(CABACContext, bytestream_end)),
"i"(H264_NORM_SHIFT_OFFSET),
"i"(H264_LPS_RANGE_OFFSET),
"i"(H264_MLPS_STATE_OFFSET)
"i"(H264_MLPS_STATE_OFFSET) TABLES_ARG
: "%"REG_c, "memory"
);
return coeff_count;
@ -105,6 +114,15 @@ static int decode_significance_8x8_x86(CABACContext *c,
x86_reg last=0;
x86_reg state;
#ifdef BROKEN_RELOCATIONS
void *tables;
__asm__ volatile(
"lea "MANGLE(ff_h264_cabac_tables)", %0 \n\t"
: "=&r"(tables)
);
#endif
__asm__ volatile(
"mov %1, %6 \n\t"
"3: \n\t"
@ -113,21 +131,24 @@ 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)", "%a14", "%a15", "%a16")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)", "%a14", "%a15", "%a16", "%18")
"mov %1, %k6 \n\t"
"test $1, %4 \n\t"
" jz 4f \n\t"
#ifdef BROKEN_RELOCATIONS
"movzbl %a17(%18, %q6), %k6\n\t"
#else
"movzbl "MANGLE(ff_h264_cabac_tables)"+%a17(%k6), %k6\n\t"
#endif
"add %11, %6 \n\t"
BRANCHLESS_GET_CABAC("%4", "(%6)", "%3", "%w3",
"%5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)", "%a14", "%a15", "%a16")
BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
"%5", "%q5", "%k0", "%b0",
"%a12(%7)", "%a13(%7)", "%a14", "%a15", "%a16", "%18")
"mov %2, %0 \n\t"
"mov %1, %k6 \n\t"
@ -157,7 +178,7 @@ static int decode_significance_8x8_x86(CABACContext *c,
"i"(H264_NORM_SHIFT_OFFSET),
"i"(H264_LPS_RANGE_OFFSET),
"i"(H264_MLPS_STATE_OFFSET),
"i"(H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET)
"i"(H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET) TABLES_ARG
: "%"REG_c, "memory"
);
return coeff_count;

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