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x86: cabac: don't load/store context values in asm

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Inspection of compiled code shows gcc handles these fine on its own.
Benchmarking also shows no measurable speed difference.

Removing the remaining cases in get_cabac_bypass_sign_x86() does
cause more substantial changes to the compiled code with uncertain
impact.

Signed-off-by: Mans Rullgard <mans@mansr.com>
This commit is contained in:
Mans Rullgard 2011-07-28 20:21:33 +01:00
parent 6c32576548
commit f5f004bc5a
2 changed files with 10 additions and 34 deletions
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12
libavcodec/x86/cabac.h
View File

@ -87,19 +87,13 @@
static av_always_inline int get_cabac_inline_x86(CABACContext *c,
uint8_t *const state)
{
int bit, low, range, tmp;
int bit, tmp;
__asm__ volatile(
"movl %a6(%5), %2 \n\t"
"movl %a7(%5), %1 \n\t"
BRANCHLESS_GET_CABAC("%0", "%5", "(%4)", "%1", "%w1", "%2",
"%3", "%b3", "%a8")
"movl %2, %a6(%5) \n\t"
"movl %1, %a7(%5) \n\t"
:"=&r"(bit), "=&r"(low), "=&r"(range), "=&q"(tmp)
"%3", "%b3", "%a6")
:"=&r"(bit), "+&r"(c->low), "+&r"(c->range), "=&q"(tmp)
:"r"(state), "r"(c),
"i"(offsetof(CABACContext, range)), "i"(offsetof(CABACContext, low)),
"i"(offsetof(CABACContext, bytestream))
: "%"REG_c, "memory"
);

32
libavcodec/x86/h264_i386.h
View File

@ -45,23 +45,18 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
int minusindex= 4-(intptr_t)index;
int bit;
x86_reg coeff_count;
int low;
int range;
__asm__ volatile(
"movl %a11(%6), %5 \n\t"
"movl %a12(%6), %3 \n\t"
"2: \n\t"
BRANCHLESS_GET_CABAC("%4", "%6", "(%1)", "%3",
"%w3", "%5", "%k0", "%b0", "%a13")
"%w3", "%5", "%k0", "%b0", "%a11")
"test $1, %4 \n\t"
" jz 3f \n\t"
"add %10, %1 \n\t"
BRANCHLESS_GET_CABAC("%4", "%6", "(%1)", "%3",
"%w3", "%5", "%k0", "%b0", "%a13")
"%w3", "%5", "%k0", "%b0", "%a11")
"sub %10, %1 \n\t"
"mov %2, %0 \n\t"
@ -85,13 +80,9 @@ static int decode_significance_x86(CABACContext *c, int max_coeff,
"4: \n\t"
"add %9, %k0 \n\t"
"shr $2, %k0 \n\t"
"movl %5, %a11(%6) \n\t"
"movl %3, %a12(%6) \n\t"
:"=&q"(coeff_count), "+r"(significant_coeff_ctx_base), "+m"(index),
"=&r"(low), "=&r"(bit), "=&r"(range)
"+&r"(c->low), "=&r"(bit), "+&r"(c->range)
:"r"(c), "m"(minusstart), "m"(end), "m"(minusindex), "m"(last_off),
"i"(offsetof(CABACContext, range)), "i"(offsetof(CABACContext, low)),
"i"(offsetof(CABACContext, bytestream))
: "%"REG_c, "memory"
);
@ -104,14 +95,9 @@ static int decode_significance_8x8_x86(CABACContext *c,
int minusindex= 4-(intptr_t)index;
int bit;
x86_reg coeff_count;
int low;
int range;
x86_reg last=0;
x86_reg state;
__asm__ volatile(
"movl %a12(%7), %5 \n\t"
"movl %a13(%7), %3 \n\t"
"mov %1, %6 \n\t"
"2: \n\t"
@ -120,7 +106,7 @@ static int decode_significance_8x8_x86(CABACContext *c,
"add %9, %6 \n\t"
BRANCHLESS_GET_CABAC("%4", "%7", "(%6)", "%3",
"%w3", "%5", "%k0", "%b0", "%a14")
"%w3", "%5", "%k0", "%b0", "%a12")
"mov %1, %k6 \n\t"
"test $1, %4 \n\t"
@ -130,7 +116,7 @@ static int decode_significance_8x8_x86(CABACContext *c,
"add %11, %6 \n\t"
BRANCHLESS_GET_CABAC("%4", "%7", "(%6)", "%3",
"%w3", "%5", "%k0", "%b0", "%a14")
"%w3", "%5", "%k0", "%b0", "%a12")
"mov %2, %0 \n\t"
"mov %1, %k6 \n\t"
@ -151,13 +137,9 @@ static int decode_significance_8x8_x86(CABACContext *c,
"4: \n\t"
"addl %8, %k0 \n\t"
"shr $2, %k0 \n\t"
"movl %5, %a12(%7) \n\t"
"movl %3, %a13(%7) \n\t"
:"=&q"(coeff_count),"+m"(last), "+m"(index), "=&r"(low), "=&r"(bit),
"=&r"(range), "=&r"(state)
:"=&q"(coeff_count),"+m"(last), "+m"(index), "+&r"(c->low), "=&r"(bit),
"+&r"(c->range), "=&r"(state)
:"r"(c), "m"(minusindex), "m"(significant_coeff_ctx_base), "m"(sig_off), "m"(last_coeff_ctx_base),
"i"(offsetof(CABACContext, range)), "i"(offsetof(CABACContext, low)),
"i"(offsetof(CABACContext, bytestream))
: "%"REG_c, "memory"
);