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Optimize png_do_expand_palette for ARM

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ARM-specific optimization processes 8 or 4 pixels at once.
Improves performance by around 10-22% on a recent ARM Chromebook.
This commit is contained in:
Richard Townsend 2018-01-25 19:03:04 +00:00 committed by Cosmin Truta
parent 2fc5ddff18
commit 7734cda20c
7 changed files with 213 additions and 10 deletions
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3
CMakeLists.txt
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@ -105,7 +105,8 @@ if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
set(libpng_arm_sources
arm/arm_init.c
arm/filter_neon.S
arm/filter_neon_intrinsics.c)
arm/filter_neon_intrinsics.c
arm/palette_neon_intrinsics.c)
if(${PNG_ARM_NEON} STREQUAL "on")
add_definitions(-DPNG_ARM_NEON_OPT=2)

3
Makefile.am
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@ -95,7 +95,8 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\
if PNG_ARM_NEON
libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
arm/filter_neon.S arm/filter_neon_intrinsics.c
arm/filter_neon.S arm/filter_neon_intrinsics.c \
arm/palette_neon_intrinsics.c
endif
if PNG_MIPS_MSA

137
arm/palette_neon_intrinsics.c Normal file
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@ -0,0 +1,137 @@
/* palette_neon_intrinsics.c - NEON optimised palette expansion functions
*
* Copyright (c) 2017-2018 Arm Holdings. All rights reserved.
* Written by Richard Townsend <Richard.Townsend@arm.com>, February 2017.
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#include "../pngpriv.h"
#if PNG_ARM_NEON_IMPLEMENTATION == 1
#include <arm_neon.h>
/* Build an RGBA palette from the RGB and separate alpha palettes. */
void
png_riffle_palette_rgba(png_structrp png_ptr, png_row_infop row_info)
{
png_const_colorp palette = png_ptr->palette;
png_bytep riffled_palette = png_ptr->riffled_palette;
png_const_bytep trans_alpha = png_ptr->trans_alpha;
int num_trans = png_ptr->num_trans;
if (row_info->bit_depth != 8) {
png_error(png_ptr, "bit_depth must be 8 for png_riffle_palette_rgba");
return;
}
/* Initially black, opaque. */
uint8x16x4_t w = {{
vdupq_n_u8(0x00),
vdupq_n_u8(0x00),
vdupq_n_u8(0x00),
vdupq_n_u8(0xff),
}};
int i;
/* First, riffle the RGB colours into a RGBA palette, the A value is
* set to opaque for now. */
for (i = 0; i < (1 << row_info->bit_depth); i += 16) {
uint8x16x3_t v = vld3q_u8((png_const_bytep)(palette + i));
w.val[0] = v.val[0];
w.val[1] = v.val[1];
w.val[2] = v.val[2];
vst4q_u8(riffled_palette + (i << 2), w);
}
/* Fix up the missing transparency values. */
for (i = 0; i < num_trans; i++) {
riffled_palette[(i << 2) + 3] = trans_alpha[i];
}
}
/* Expands a palettized row into RGBA. */
int
png_do_expand_palette_neon_rgba(png_structrp png_ptr, png_row_infop row_info,
png_const_bytep row, const png_bytepp ssp, const png_bytepp ddp)
{
png_uint_32 row_width = row_info->width;
const png_uint_32 *riffled_palette = (const png_uint_32*)png_ptr->riffled_palette;
const png_int_32 pixels_per_chunk = 4;
if (row_width < pixels_per_chunk) {
return 0;
}
/* This function originally gets the last byte of the output row.
The NEON part writes forward from a given position, so we have
to seek this back by 4 pixels x 4 bytes. */
*ddp = *ddp - ((pixels_per_chunk * sizeof(png_uint_32)) - 1);
int i;
for (i = 0; i < row_width; i += pixels_per_chunk) {
uint32x4_t cur;
png_bytep sp = *ssp - i, dp = *ddp - (i << 2);
cur = vld1q_dup_u32 (riffled_palette + *(sp - 3));
cur = vld1q_lane_u32(riffled_palette + *(sp - 2), cur, 1);
cur = vld1q_lane_u32(riffled_palette + *(sp - 1), cur, 2);
cur = vld1q_lane_u32(riffled_palette + *(sp - 0), cur, 3);
vst1q_u32((void *)dp, cur);
}
if (i != row_width) {
i -= pixels_per_chunk; /* Remove the amount that wasn't processed. */
}
/* Decrement output pointers. */
*ssp = *ssp - i;
*ddp = *ddp - (i << 2);
return i;
}
/* Expands a palettized row into RGB format. */
int
png_do_expand_palette_neon_rgb(png_structrp png_ptr, png_row_infop row_info,
png_const_bytep row, const png_bytepp ssp, const png_bytepp ddp)
{
png_uint_32 row_width = row_info->width;
png_const_bytep palette = (png_const_bytep)png_ptr->palette;
const png_uint_32 pixels_per_chunk = 8;
if (row_width <= pixels_per_chunk) {
return 0;
}
/* Seeking this back by 8 pixels x 3 bytes. */
*ddp = *ddp - ((pixels_per_chunk * sizeof(png_color)) - 1);
int i;
for (i = 0; i < row_width; i += pixels_per_chunk) {
uint8x8x3_t cur;
png_bytep sp = *ssp - i, dp = *ddp - ((i << 1) + i);
cur = vld3_dup_u8(palette + sizeof(png_color) * (*(sp - 7)));
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 6)), cur, 1);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 5)), cur, 2);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 4)), cur, 3);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 3)), cur, 4);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 2)), cur, 5);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 1)), cur, 6);
cur = vld3_lane_u8(palette + sizeof(png_color) * (*(sp - 0)), cur, 7);
vst3_u8((void *)dp, cur);
}
if (i != row_width) {
i -= pixels_per_chunk; /* Remove the amount that wasn't processed. */
}
/* Decrement output pointers. */
*ssp = *ssp - i;
*ddp = *ddp - ((i << 1) + i);
return i;
}
#endif /* PNG_ARM_NEON_IMPLEMENTATION */

23
pngpriv.h
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@ -2117,6 +2117,29 @@ PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
png_const_charp key, png_bytep new_key), PNG_EMPTY);
#if PNG_ARM_NEON_IMPLEMENTATION == 1
PNG_INTERNAL_FUNCTION(void,
png_riffle_palette_rgba,
(png_structrp, png_row_infop),
PNG_EMPTY);
PNG_INTERNAL_FUNCTION(int,
png_do_expand_palette_neon_rgba,
(png_structrp,
png_row_infop,
png_const_bytep,
const png_bytepp,
const png_bytepp),
PNG_EMPTY);
PNG_INTERNAL_FUNCTION(int,
png_do_expand_palette_neon_rgb,
(png_structrp,
png_row_infop,
png_const_bytep,
const png_bytepp,
const png_bytepp),
PNG_EMPTY);
#endif
/* Maintainer: Put new private prototypes here ^ */
#include "pngdebug.h"

49
pngrtran.c
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@ -18,6 +18,13 @@
#include "pngpriv.h"
#ifdef PNG_ARM_NEON_IMPLEMENTATION
#if PNG_ARM_NEON_IMPLEMENTATION == 1
#define PNG_ARM_NEON_INTRINSICS_AVAILABLE
#include <arm_neon.h>
#endif
#endif
#ifdef PNG_READ_SUPPORTED
/* Set the action on getting a CRC error for an ancillary or critical chunk. */
@ -4195,8 +4202,9 @@ png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr)
* upon whether you supply trans and num_trans.
*/
static void
png_do_expand_palette(png_row_infop row_info, png_bytep row,
png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
png_do_expand_palette(png_structrp png_ptr, png_row_infop row_info,
png_bytep row, png_const_colorp palette, png_const_bytep trans_alpha,
int num_trans)
{
int shift, value;
png_bytep sp, dp;
@ -4300,14 +4308,22 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
sp = row + (size_t)row_width - 1;
dp = row + ((size_t)row_width << 2) - 1;
for (i = 0; i < row_width; i++)
i = 0;
#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
if (png_ptr->riffled_palette != NULL) {
/* The RGBA optimization works with png_ptr->bit_depth == 8
but sometimes row_info->bit_depth has been changed to 8.
In these cases, the palette hasn't been riffled. */
i = png_do_expand_palette_neon_rgba(png_ptr, row_info, row, &sp, &dp);
}
#endif
for (; i < row_width; i++)
{
if ((int)(*sp) >= num_trans)
*dp-- = 0xff;
else
*dp-- = trans_alpha[*sp];
*dp-- = palette[*sp].blue;
*dp-- = palette[*sp].green;
*dp-- = palette[*sp].red;
@ -4324,8 +4340,12 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
{
sp = row + (size_t)row_width - 1;
dp = row + (size_t)(row_width * 3) - 1;
i = 0;
#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
i = png_do_expand_palette_neon_rgb(png_ptr, row_info, row, &sp, &dp);
#endif
for (i = 0; i < row_width; i++)
for (; i < row_width; i++)
{
*dp-- = palette[*sp].blue;
*dp-- = palette[*sp].green;
@ -4739,8 +4759,21 @@ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info)
{
if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
{
png_do_expand_palette(row_info, png_ptr->row_buf + 1,
png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
#ifdef PNG_ARM_NEON_INTRINSICS_AVAILABLE
if ((png_ptr->num_trans > 0) && (png_ptr->bit_depth == 8)) {
/* Allocate space for the decompressed full palette. */
if (png_ptr->riffled_palette == NULL) {
png_ptr->riffled_palette = png_malloc(png_ptr, 256*4);
if (png_ptr->riffled_palette == NULL) {
png_error(png_ptr, "NULL row buffer");
}
/* Build the RGBA palette. */
png_riffle_palette_rgba(png_ptr, row_info);
}
}
#endif
png_do_expand_palette(png_ptr, row_info, png_ptr->row_buf + 1,
png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
}
else

4
pngstruct.h
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@ -228,6 +228,10 @@ struct png_struct_def
* big_row_buf; while writing it is separately
* allocated.
*/
#ifdef PNG_READ_EXPAND_SUPPORTED
/* Buffer to accelerate palette transformations. */
png_bytep riffled_palette;
#endif
#ifdef PNG_WRITE_FILTER_SUPPORTED
png_bytep try_row; /* buffer to save trial row when filtering */
png_bytep tst_row; /* buffer to save best trial row when filtering */

4
pngwrite.c
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@ -948,6 +948,10 @@ png_write_destroy(png_structrp png_ptr)
png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
png_free(png_ptr, png_ptr->row_buf);
png_ptr->row_buf = NULL;
#ifdef PNG_READ_EXPANDED_SUPPORTED
png_free(png_ptr, png_ptr->riffled_palette);
png_ptr->riffled_palette = NULL;
#endif
#ifdef PNG_WRITE_FILTER_SUPPORTED
png_free(png_ptr, png_ptr->prev_row);
png_free(png_ptr, png_ptr->try_row);