[FFmpeg-cvslog] h264: new assembly version of get_cabac for x86_64 with PIC
Roland Scheidegger
git at videolan.org
Sat Apr 28 21:10:21 CEST 2012
ffmpeg | branch: master | Roland Scheidegger <rscheidegger_lists at hispeed.ch> | Fri Apr 27 22:19:39 2012 +0200| [9b9df1cdff149db5bbe6726b236934c5b5fbe21d] | committer: Ronald S. Bultje
h264: new assembly version of get_cabac for x86_64 with PIC
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 at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9b9df1cdff149db5bbe6726b236934c5b5fbe21d
---
libavcodec/h264_cabac.c | 2 +-
libavcodec/x86/cabac.h | 90 ++++++++++++++++++++++++++++++++++++++++---
libavcodec/x86/h264_i386.h | 53 ++++++++++++++++++--------
3 files changed, 121 insertions(+), 24 deletions(-)
diff --git a/libavcodec/h264_cabac.c b/libavcodec/h264_cabac.c
index f27e72f..08a6a5b 100644
--- a/libavcodec/h264_cabac.c
+++ b/libavcodec/h264_cabac.c
@@ -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 {
diff --git a/libavcodec/x86/cabac.h b/libavcodec/x86/cabac.h
index 32ce2b2..6fc2ddb 100644
--- a/libavcodec/x86/cabac.h
+++ b/libavcodec/x86/cabac.h
@@ -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)
diff --git a/libavcodec/x86/h264_i386.h b/libavcodec/x86/h264_i386.h
index add795e..10ea32e 100644
--- a/libavcodec/x86/h264_i386.h
+++ b/libavcodec/x86/h264_i386.h
@@ -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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