fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-06-05 02:08:18 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

gallivm: optimize yuv decoding

Browse source 
this is more a proof to show vector shifts on x86 with per-element shift count
are evil. Since we can avoid the shift with a single compare/select, use that
instead. Replaces more than 20 instructions (and slow ones at that) with about 3,
and cuts compiled shader size with mesa's yuvsqure demo by over 10%
(no performance measurements done - but selection is blazing fast).
Might want to revisit that for future cpus - unfortunately AVX won't have vector
shifts neither, but AMD's XOP will, but even in that case using selection here
is probably not slower.
This commit is contained in:
Roland Scheidegger 2010-09-24 15:17:07 +02:00 • committed by José Fonseca
parent 46d05d4ef9
commit 049a8cce76
1 changed files with 55 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

64
src/gallium/auxiliary/gallivm/lp_bld_format_yuv.c
View file

@ -35,6 +35,7 @@
#include "util/u_format.h"
#include "util/u_cpu_detect.h"
#include "lp_bld_arit.h"
#include "lp_bld_type.h"
@ -42,7 +43,7 @@
#include "lp_bld_conv.h"
#include "lp_bld_gather.h"
#include "lp_bld_format.h"
#include "lp_bld_logic.h"
/**
* Extract Y, U, V channels from packed UYVY.
@ -59,7 +60,7 @@ uyvy_to_yuv_soa(LLVMBuilderRef builder,
LLVMValueRef *v)
{
struct lp_type type;
LLVMValueRef shift, mask;
LLVMValueRef mask;
memset(&type, 0, sizeof type);
type.width = 32;
@ -69,14 +70,37 @@ uyvy_to_yuv_soa(LLVMBuilderRef builder,
assert(lp_check_value(type, i));
/*
* y = (uyvy >> 16*i) & 0xff
* y = (uyvy >> (16*i + 8)) & 0xff
* u = (uyvy ) & 0xff
* v = (uyvy >> 16 ) & 0xff
*/
shift = LLVMBuildMul(builder, i, lp_build_const_int_vec(type, 16), "");
shift = LLVMBuildAdd(builder, shift, lp_build_const_int_vec(type, 8), "");
*y = LLVMBuildLShr(builder, packed, shift, "");
#if defined(PIPE_ARCH_X86) || defined(PIPE_ARCH_X86_64)
/*
* Avoid shift with per-element count.
* No support on x86, gets translated to roughly 5 instructions
* per element. Didn't measure performance but cuts shader size
* by quite a bit (less difference if cpu has no sse4.1 support).
*/
if (util_cpu_caps.has_sse2 && n == 4) {
LLVMValueRef sel, tmp, tmp2;
struct lp_build_context bld32;
lp_build_context_init(&bld32, builder, type);
tmp = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(type, 8), "");
tmp2 = LLVMBuildLShr(builder, tmp, lp_build_const_int_vec(type, 16), "");
sel = lp_build_compare(builder, type, PIPE_FUNC_EQUAL, i, lp_build_const_int_vec(type, 0));
*y = lp_build_select(&bld32, sel, tmp, tmp2);
} else
#endif
{
LLVMValueRef shift;
shift = LLVMBuildMul(builder, i, lp_build_const_int_vec(type, 16), "");
shift = LLVMBuildAdd(builder, shift, lp_build_const_int_vec(type, 8), "");
*y = LLVMBuildLShr(builder, packed, shift, "");
}
*u = packed;
*v = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(type, 16), "");
@ -103,7 +127,7 @@ yuyv_to_yuv_soa(LLVMBuilderRef builder,
LLVMValueRef *v)
{
struct lp_type type;
LLVMValueRef shift, mask;
LLVMValueRef mask;
memset(&type, 0, sizeof type);
type.width = 32;
@ -118,8 +142,30 @@ yuyv_to_yuv_soa(LLVMBuilderRef builder,
* v = (yuyv >> 24 ) & 0xff
*/
shift = LLVMBuildMul(builder, i, lp_build_const_int_vec(type, 16), "");
*y = LLVMBuildLShr(builder, packed, shift, "");
#if defined(PIPE_ARCH_X86) || defined(PIPE_ARCH_X86_64)
/*
* Avoid shift with per-element count.
* No support on x86, gets translated to roughly 5 instructions
* per element. Didn't measure performance but cuts shader size
* by quite a bit (less difference if cpu has no sse4.1 support).
*/
if (util_cpu_caps.has_sse2 && n == 4) {
LLVMValueRef sel, tmp;
struct lp_build_context bld32;
lp_build_context_init(&bld32, builder, type);
tmp = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(type, 16), "");
sel = lp_build_compare(builder, type, PIPE_FUNC_EQUAL, i, lp_build_const_int_vec(type, 0));
*y = lp_build_select(&bld32, sel, packed, tmp);
} else
#endif
{
LLVMValueRef shift;
shift = LLVMBuildMul(builder, i, lp_build_const_int_vec(type, 16), "");
*y = LLVMBuildLShr(builder, packed, shift, "");
}
*u = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(type, 8), "");
*v = LLVMBuildLShr(builder, packed, lp_build_const_int_vec(type, 24), "");