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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: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Roland Scheidegger
Michael Niedermayer
parent
3194ab78a6
commit
a812b599b5
@ -1659,7 +1659,7 @@ decode_cabac_residual_internal(H264Context *h, DCTELEM *block,
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index[coeff_count++] = last;\
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}
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const uint8_t *sig_off = significant_coeff_flag_offset_8x8[MB_FIELD];
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#if ARCH_X86 && HAVE_7REGS && !defined(BROKEN_RELOCATIONS)
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#if ARCH_X86 && HAVE_7REGS
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coeff_count= decode_significance_8x8_x86(CC, significant_coeff_ctx_base, index,
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last_coeff_ctx_base, sig_off);
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} else {
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@ -24,8 +24,71 @@
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#include "libavcodec/cabac.h"
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#include "libavutil/attributes.h"
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#include "libavutil/x86_cpu.h"
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#include "libavutil/internal.h"
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#include "config.h"
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#ifdef BROKEN_RELOCATIONS
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#define RIP_ARG , "r"(rip)
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#if HAVE_FAST_CMOV
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#define BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
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"cmp "low" , "tmp" \n\t"\
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"cmova %%ecx , "range" \n\t"\
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"sbb %%rcx , %%rcx \n\t"\
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"and %%ecx , "tmp" \n\t"\
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"xor %%rcx , "retq" \n\t"\
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"sub "tmp" , "low" \n\t"
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#else /* HAVE_FAST_CMOV */
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#define BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
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/* P4 Prescott has crappy cmov,sbb,64bit shift so avoid them */ \
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"sub "low" , "tmp" \n\t"\
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"sar $31 , "tmp" \n\t"\
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"sub %%ecx , "range" \n\t"\
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"and "tmp" , "range" \n\t"\
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"add %%ecx , "range" \n\t"\
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"shl $17 , %%ecx \n\t"\
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"and "tmp" , %%ecx \n\t"\
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"sub %%ecx , "low" \n\t"\
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"xor "tmp" , "ret" \n\t"\
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"movslq "ret" , "retq" \n\t"
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#endif /* HAVE_FAST_CMOV */
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#define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, rip) \
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"movzbl "statep" , "ret" \n\t"\
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"mov "range" , "tmp" \n\t"\
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"and $0xC0 , "range" \n\t"\
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"lea ("ret", "range", 2), %%ecx \n\t"\
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"movzbl ff_h264_lps_range-1b("rip", %%rcx), "range" \n\t"\
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"sub "range" , "tmp" \n\t"\
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"mov "tmp" , %%ecx \n\t"\
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"shl $17 , "tmp" \n\t"\
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BRANCHLESS_GET_CABAC_UPDATE(ret, retq, low, range, tmp) \
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"movzbl ff_h264_norm_shift-1b("rip", "rangeq"), %%ecx \n\t"\
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"shl %%cl , "range" \n\t"\
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"movzbl ff_h264_mlps_state-1b+128("rip", "retq"), "tmp" \n\t"\
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"shl %%cl , "low" \n\t"\
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"mov "tmpbyte" , "statep" \n\t"\
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"test "lowword" , "lowword" \n\t"\
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" jnz 2f \n\t"\
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"mov "byte" , %%"REG_c" \n\t"\
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"add"OPSIZE" $2 , "byte" \n\t"\
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"movzwl (%%"REG_c") , "tmp" \n\t"\
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"lea -1("low") , %%ecx \n\t"\
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"xor "low" , %%ecx \n\t"\
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"shr $15 , %%ecx \n\t"\
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"bswap "tmp" \n\t"\
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"shr $15 , "tmp" \n\t"\
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"movzbl ff_h264_norm_shift-1b("rip", %%rcx), %%ecx \n\t"\
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"sub $0xFFFF , "tmp" \n\t"\
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"neg %%ecx \n\t"\
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"add $7 , %%ecx \n\t"\
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"shl %%cl , "tmp" \n\t"\
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"add "tmp" , "low" \n\t"\
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"2: \n\t"
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#else /* BROKEN_RELOCATIONS */
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#define RIP_ARG
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#if HAVE_FAST_CMOV
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#define BRANCHLESS_GET_CABAC_UPDATE(ret, statep, low, range, tmp)\
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"mov "tmp" , %%ecx \n\t"\
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@ -51,7 +114,7 @@
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"xor "tmp" , "ret" \n\t"
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#endif /* HAVE_FAST_CMOV */
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#define BRANCHLESS_GET_CABAC(ret, statep, low, lowword, range, tmp, tmpbyte, byte, end) \
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#define BRANCHLESS_GET_CABAC(ret, retq, statep, low, lowword, range, rangeq, tmp, tmpbyte, byte, end, rip) \
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"movzbl "statep" , "ret" \n\t"\
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"mov "range" , "tmp" \n\t"\
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"and $0xC0 , "range" \n\t"\
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@ -81,28 +144,39 @@
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"add "tmp" , "low" \n\t"\
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"2: \n\t"
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#endif /* BROKEN_RELOCATIONS */
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#if HAVE_7REGS && !defined(BROKEN_RELOCATIONS) && !(defined(__i386) && defined(__clang__) && (__clang_major__<2 || (__clang_major__==2 && __clang_minor__<10)))\
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&& !(defined(__i386) && !defined(__clang__) && defined(__llvm__) && __GNUC__==4 && __GNUC_MINOR__==2 && __GNUC_PATCHLEVEL__<=1)
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#if HAVE_7REGS && !(defined(__i386) && defined(__clang__) && (__clang_major__<2 || (__clang_major__==2 && __clang_minor__<10)))\
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&& !(defined(__i386) && !defined(__clang__) && defined(__llvm__) && __GNUC__==4 && __GNUC_MINOR__==2 && __GNUC_PATCHLEVEL__<=1)
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#define get_cabac_inline get_cabac_inline_x86
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static av_always_inline int get_cabac_inline_x86(CABACContext *c,
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uint8_t *const state)
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{
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int bit, tmp;
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#ifdef BROKEN_RELOCATIONS
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int *rip;
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__asm__ volatile(
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BRANCHLESS_GET_CABAC("%0", "(%4)", "%1", "%w1",
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"%2", "%3", "%b3",
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"%a6(%5)", "%a7(%5)")
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"1: \n\t"
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"lea 1b(%%rip), %0 \n\t"
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: "=&r"(rip)
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);
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#endif
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__asm__ volatile(
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BRANCHLESS_GET_CABAC("%0", "%q0", "(%4)", "%1", "%w1",
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"%2", "%q2", "%3", "%b3",
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"%a6(%5)", "%a7(%5)", "%8")
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: "=&r"(bit), "+&r"(c->low), "+&r"(c->range), "=&q"(tmp)
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: "r"(state), "r"(c),
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"i"(offsetof(CABACContext, bytestream)),
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"i"(offsetof(CABACContext, bytestream_end))
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"i"(offsetof(CABACContext, bytestream_end)) RIP_ARG
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: "%"REG_c, "memory"
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);
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return bit & 1;
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}
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#endif /* HAVE_7REGS && !defined(BROKEN_RELOCATIONS) */
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#endif /* HAVE_7REGS */
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#define get_cabac_bypass_sign get_cabac_bypass_sign_x86
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static av_always_inline int get_cabac_bypass_sign_x86(CABACContext *c, int val)
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@ -36,7 +36,7 @@
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//FIXME use some macros to avoid duplicating get_cabac (cannot be done yet
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//as that would make optimization work hard)
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#if HAVE_7REGS && !defined(BROKEN_RELOCATIONS)
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#if HAVE_7REGS
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static int decode_significance_x86(CABACContext *c, int max_coeff,
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uint8_t *significant_coeff_ctx_base,
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int *index, x86_reg last_off){
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@ -45,20 +45,31 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
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int minusindex= 4-(intptr_t)index;
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int bit;
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x86_reg coeff_count;
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#ifdef BROKEN_RELOCATIONS
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int *rip;
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__asm__ volatile(
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"1: \n\t"
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"lea 1b(%%rip), %0 \n\t"
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: "=&r"(rip)
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);
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#endif
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__asm__ volatile(
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"3: \n\t"
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BRANCHLESS_GET_CABAC("%4", "(%1)", "%3", "%w3",
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"%5", "%k0", "%b0",
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"%a11(%6)", "%a12(%6)")
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BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
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"%5", "%q5", "%k0", "%b0",
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"%a11(%6)", "%a12(%6)", "%13")
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"test $1, %4 \n\t"
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" jz 4f \n\t"
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"add %10, %1 \n\t"
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BRANCHLESS_GET_CABAC("%4", "(%1)", "%3", "%w3",
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"%5", "%k0", "%b0",
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"%a11(%6)", "%a12(%6)")
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BRANCHLESS_GET_CABAC("%4", "%q4", "(%1)", "%3", "%w3",
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"%5", "%q5", "%k0", "%b0",
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"%a11(%6)", "%a12(%6)", "%13")
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"sub %10, %1 \n\t"
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"mov %2, %0 \n\t"
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@ -86,7 +97,7 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
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"+&r"(c->low), "=&r"(bit), "+&r"(c->range)
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: "r"(c), "m"(minusstart), "m"(end), "m"(minusindex), "m"(last_off),
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"i"(offsetof(CABACContext, bytestream)),
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"i"(offsetof(CABACContext, bytestream_end))
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"i"(offsetof(CABACContext, bytestream_end)) RIP_ARG
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: "%"REG_c, "memory"
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);
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return coeff_count;
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@ -100,6 +111,17 @@ static int decode_significance_8x8_x86(CABACContext *c,
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x86_reg coeff_count;
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x86_reg last=0;
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x86_reg state;
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#ifdef BROKEN_RELOCATIONS
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int *rip;
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__asm__ volatile(
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"1: \n\t"
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"lea 1b(%%rip), %0 \n\t"
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: "=&r"(rip)
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);
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#endif
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__asm__ volatile(
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"mov %1, %6 \n\t"
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"3: \n\t"
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@ -108,20 +130,24 @@ static int decode_significance_8x8_x86(CABACContext *c,
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"movzbl (%0, %6), %k6 \n\t"
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"add %9, %6 \n\t"
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BRANCHLESS_GET_CABAC("%4", "(%6)", "%3", "%w3",
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"%5", "%k0", "%b0",
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"%a12(%7)", "%a13(%7)")
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BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
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"%5", "%q5", "%k0", "%b0",
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"%a12(%7)", "%a13(%7)", "%14")
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"mov %1, %k6 \n\t"
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"test $1, %4 \n\t"
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" jz 4f \n\t"
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"movzbl "MANGLE(last_coeff_flag_offset_8x8)"(%k6), %k6\n\t"
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#ifdef BROKEN_RELOCATIONS
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"movzbl last_coeff_flag_offset_8x8-1b(%14, %q6), %k6\n\t"
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#else
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"movzbl last_coeff_flag_offset_8x8(%k6), %k6\n\t"
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#endif
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"add %11, %6 \n\t"
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BRANCHLESS_GET_CABAC("%4", "(%6)", "%3", "%w3",
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"%5", "%k0", "%b0",
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"%a12(%7)", "%a13(%7)")
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BRANCHLESS_GET_CABAC("%4", "%q4", "(%6)", "%3", "%w3",
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"%5", "%q5", "%k0", "%b0",
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"%a12(%7)", "%a13(%7)", "%14")
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"mov %2, %0 \n\t"
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"mov %1, %k6 \n\t"
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@ -147,7 +173,7 @@ static int decode_significance_8x8_x86(CABACContext *c,
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: "r"(c), "m"(minusindex), "m"(significant_coeff_ctx_base),
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"m"(sig_off), "m"(last_coeff_ctx_base),
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"i"(offsetof(CABACContext, bytestream)),
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"i"(offsetof(CABACContext, bytestream_end))
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"i"(offsetof(CABACContext, bytestream_end)) RIP_ARG
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: "%"REG_c, "memory"
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);
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return coeff_count;
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