Added initial code for PowerPC VSX optimisation

Makefile.am

@@ -102,6 +102,11 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
 	mips/filter_msa_intrinsics.c
 endif
 
+if PNG_POWERPC_VSX
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += powerpc/powerpc_init.c\
+        powerpc/filter_vsx_intrinsics.c
+endif
+
 nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
 
 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \

configure.ac

@@ -391,6 +391,52 @@ AM_CONDITIONAL([PNG_MIPS_MSA],
       mipsel*|mips64el*) :;;
     esac])
 
+# PowerPC
+# ===
+#
+# PowerPC VSX (SIMD) support.
+
+AC_ARG_ENABLE([powerpc-vsx],
+AS_HELP_STRING([[[--enable-powerpc-vsx]]],
+      [Enable POWERPC VSX optimizations: =no/off, check, api, yes/on:]
+      [no/off: disable the optimizations; check: use internal checking code]
+      [(deprecated and poorly supported); api: disable by default, enable by]
+      [a call to png_set_option; yes/on: turn on unconditionally.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling on __ppc64__ systems:
+         AC_DEFINE([PNG_POWERPC_VSX_OPT], [0],
+                   [Disable POWERPC VSX optimizations])
+         # Prevent inclusion of the platform specific files below:
+         enable_powerpc_vsx=no;;
+      check)
+         AC_DEFINE([PNG_POWERPC_VSX_CHECK_SUPPORTED], [],
+                   [Check for POWERPC VSX support at run-time]);;
+      api)
+         AC_DEFINE([PNG_POWERPC_VSX_API_SUPPORTED], [],
+                   [Turn on POWERPC VSX optimizations at run-time]);;
+      yes|on)
+         AC_DEFINE([PNG_POWERPC_VSX_OPT], [2],
+                   [Enable POWERPC VSX optimizations])
+         AC_MSG_WARN([--enable-powerpc-vsx: please specify 'check' or 'api', if]
+            [you want the optimizations unconditionally pass '-maltivec and -mabi=altivec']
+            [to the compiler.]);;
+      *)
+         AC_MSG_ERROR([--enable-powerpc-vsx=${enable_powerpc_vsx}: invalid value])
+   esac])
+
+# Add PowerPC specific files to all builds where the host_cpu is powerpc('powerpc*') or
+# where POWERPC optimizations were explicitly requested (this allows a fallback if a
+# future host CPU does not match 'powerpc*')
+
+AM_CONDITIONAL([PNG_POWERPC_VSX],
+   [test "$enable_powerpc_vsx" != 'no' &&
+    case "$host_cpu" in
+      powerpc*) :;;
+    esac])
+
+
 AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
 
 # Config files, substituting as above

png.h

@@ -3225,7 +3225,10 @@ PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
 #  define PNG_MIPS_MSA   6 /* HARDWARE: MIPS Msa SIMD instructions supported */
 #endif
 #define PNG_IGNORE_ADLER32 8
-#define PNG_OPTION_NEXT  10 /* Next option - numbers must be even */
+#ifdef PNG_POWERPC_VSX_API_SUPPORTED
+#  define PNG_POWERPC_VSX   10 /* HARDWARE: PowerPC VSX SIMD instructions supported */
+#endif
+#define PNG_OPTION_NEXT  12 /* Next option - numbers must be even */
 
 /* Return values: NOTE: there are four values and 'off' is *not* zero */
 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */

pngpriv.h

@@ -190,6 +190,14 @@
 #  endif
 #endif
 
+#ifndef PNG_POWERPC_VSX_OPT
+#  if defined(__ppc64__) && defined(__ALTIVEC__) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
+#     define PNG_POWERPC_VSX_OPT 2
+#  else
+#     define PNG_POWERPC_VSX_OPT 0
+#  endif
+#endif
+
 #ifndef PNG_INTEL_SSE_OPT
 #   ifdef PNG_INTEL_SSE
       /* Only check for SSE if the build configuration has been modified to
@@ -246,6 +254,11 @@
 #  endif
 #endif /* PNG_MIPS_MSA_OPT > 0 */
 
+#if PNG_POWERPC_VSX_OPT > 0
+#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_vsx
+#  define PNG_POWERPC_VSX_IMPLEMENTATION 1
+#endif
+
 
 /* Is this a build of a DLL where compilation of the object modules requires
  * different preprocessor settings to those required for a simple library?  If
@@ -1292,6 +1305,23 @@ PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
 #endif
 
+#if PNG_POWERPC_VSX_OPT > 0
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_up_vsx,(png_row_infop row_info,
+    png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_vsx,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_vsx,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_vsx,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_vsx,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_vsx,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_vsx,(png_row_infop
+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
+#endif
+
 #if PNG_INTEL_SSE_IMPLEMENTATION > 0
 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);

powerpc/filter_vsx_intrinsics.c

@@ -0,0 +1,233 @@
+
+/* filter_vsx_intrinsics.c - PowerPC optimised filter functions
+ *
+ * Copyright (c) 2016 Glenn Randers-Pehrson
+ * Written by Vadim Barkov, 2017.
+ * Last changed in libpng 1.6.25 [September 1, 2016]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+#include <stdio.h>
+#include <stdint.h>
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+/* This code requires -maltivec and -mabi=altivec on the command line: */
+#if PNG_POWERPC_VSX_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
+
+/* libpng row pointers are not necessarily aligned to any particular boundary,
+ * however this code will only work with appropriate alignment.  arm/arm_init.c
+ * checks for this (and will not compile unless it is done). This code uses
+ * variants of png_aligncast to avoid compiler warnings.
+ */
+#define png_ptr(type,pointer) png_aligncast(type *,pointer)
+#define png_ptrc(type,pointer) png_aligncastconst(const type *,pointer)
+
+/*#include <altivec.h>*/
+
+#if PNG_POWERPC_VSX_OPT > 0
+
+void png_read_filter_row_up_vsx(png_row_infop row_info, png_bytep row,
+                                png_const_bytep prev_row)
+{
+   png_size_t i;
+   png_size_t istop = row_info->rowbytes;
+   png_bytep rp = row;
+   png_const_bytep pp = prev_row;
+
+   for (i = 0; i < istop; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*pp++)) & 0xff);
+      rp++;
+   }
+
+}
+
+void png_read_filter_row_sub4_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+   png_size_t i;
+   png_size_t istop = row_info->rowbytes;
+   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+   png_bytep rp = row + bpp;
+
+   PNG_UNUSED(prev_row)
+
+   for (i = bpp; i < istop; i++)
+   {
+      *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+      rp++;
+   }
+}
+
+void png_read_filter_row_sub3_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+    png_size_t i;
+    png_size_t istop = row_info->rowbytes;
+    unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+    png_bytep rp = row + bpp;
+
+    PNG_UNUSED(prev_row)
+
+    for (i = bpp; i < istop; i++)
+    {
+       *rp = (png_byte)(((int)(*rp) + (int)(*(rp-bpp))) & 0xff);
+       rp++;
+    }
+}
+
+void png_read_filter_row_avg4_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+    png_size_t i;
+    png_bytep rp = row;
+    png_const_bytep pp = prev_row;
+    unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+    png_size_t istop = row_info->rowbytes - bpp;
+
+    for (i = 0; i < bpp; i++)
+    {
+       *rp = (png_byte)(((int)(*rp) +
+          ((int)(*pp++) / 2 )) & 0xff);
+
+       rp++;
+    }
+
+    for (i = 0; i < istop; i++)
+    {
+       *rp = (png_byte)(((int)(*rp) +
+          (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+       rp++;
+    }
+}
+
+void png_read_filter_row_avg3_vsx(png_row_infop row_info, png_bytep row,
+                                  png_const_bytep prev_row)
+{
+    png_size_t i;
+    png_bytep rp = row;
+    png_const_bytep pp = prev_row;
+    unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+    png_size_t istop = row_info->rowbytes - bpp;
+
+    for (i = 0; i < bpp; i++)
+    {
+       *rp = (png_byte)(((int)(*rp) +
+          ((int)(*pp++) / 2 )) & 0xff);
+
+       rp++;
+    }
+
+    for (i = 0; i < istop; i++)
+    {
+       *rp = (png_byte)(((int)(*rp) +
+          (int)(*pp++ + *(rp-bpp)) / 2 ) & 0xff);
+
+       rp++;
+    }
+}
+
+void png_read_filter_row_paeth4_vsx(png_row_infop row_info,
+                                    png_bytep row,
+                                    png_const_bytep prev_row)
+{
+    unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+    png_bytep rp_end = row + bpp;
+
+    /* Process the first pixel in the row completely (this is the same as 'up'
+     * because there is only one candidate predictor for the first row).
+     */
+    while (row < rp_end)
+    {
+       int a = *row + *prev_row++;
+       *row++ = (png_byte)a;
+    }
+
+    /* Remainder */
+    rp_end = rp_end + (row_info->rowbytes - bpp);
+
+    while (row < rp_end)
+    {
+       int a, b, c, pa, pb, pc, p;
+
+       c = *(prev_row - bpp);
+       a = *(row - bpp);
+       b = *prev_row++;
+
+       p = b - c;
+       pc = a - c;
+
+ #ifdef PNG_USE_ABS
+       pa = abs(p);
+       pb = abs(pc);
+       pc = abs(p + pc);
+ #else
+       pa = p < 0 ? -p : p;
+       pb = pc < 0 ? -pc : pc;
+       pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+ #endif
+
+       if (pb < pa) pa = pb, a = b;
+       if (pc < pa) a = c;
+
+       a += *row;
+       *row++ = (png_byte)a;
+    }
+}
+
+void png_read_filter_row_paeth3_vsx(png_row_infop row_info,
+                                    png_bytep row,
+                                    png_const_bytep prev_row)
+{
+    unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
+    png_bytep rp_end = row + bpp;
+
+    /* Process the first pixel in the row completely (this is the same as 'up'
+     * because there is only one candidate predictor for the first row).
+     */
+    while (row < rp_end)
+    {
+       int a = *row + *prev_row++;
+       *row++ = (png_byte)a;
+    }
+
+    /* Remainder */
+    rp_end = rp_end + (row_info->rowbytes - bpp);
+
+    while (row < rp_end)
+    {
+       int a, b, c, pa, pb, pc, p;
+
+       c = *(prev_row - bpp);
+       a = *(row - bpp);
+       b = *prev_row++;
+
+       p = b - c;
+       pc = a - c;
+
+ #ifdef PNG_USE_ABS
+       pa = abs(p);
+       pb = abs(pc);
+       pc = abs(p + pc);
+ #else
+       pa = p < 0 ? -p : p;
+       pb = pc < 0 ? -pc : pc;
+       pc = (p + pc) < 0 ? -(p + pc) : p + pc;
+ #endif
+
+       if (pb < pa) pa = pb, a = b;
+       if (pc < pa) a = c;
+
+       a += *row;
+       *row++ = (png_byte)a;
+    }
+}
+
+#endif /* PNG_POWERPC_VSX_OPT > 0 */
+#endif /* PNG_POWERPC_VSX_IMPLEMENTATION == 1 (intrinsics) */
+#endif /* READ */

powerpc/powerpc_init.c

@@ -0,0 +1,126 @@
+
+/* powerpc_init.c - POWERPC optimised filter functions
+ *
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
+ * called.
+ */
+#define _POSIX_SOURCE 1
+
+#include <stdio.h>
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+#if PNG_POWERPC_VSX_OPT > 0
+#ifdef PNG_POWERPC_VSX_CHECK_SUPPORTED /* Do run-time checks */
+/* WARNING: it is strongly recommended that you do not build libpng with
+ * run-time checks for CPU features if at all possible.  In the case of the PowerPC
+ * VSX instructions there is no processor-specific way of detecting the
+ * presence of the required support, therefore run-time detection is extremely
+ * OS specific.
+ *
+ * You may set the macro PNG_POWERPC_VSX_FILE to the file name of file containing
+ * a fragment of C source code which defines the png_have_vsx function.  There
+ * are a number of implementations in contrib/powerpc-vsx, but the only one that
+ * has partial support is contrib/powerpc-vsx/linux.c - a generic Linux
+ * implementation which reads /proc/cpufino.
+ */
+#ifndef PNG_POWERPC_VSX_FILE
+#  ifdef __linux__
+#     define  PNG_POWERPC_VSX_FILE "contrib/powerpc-vsx/linux.c"
+#  endif
+#endif
+
+#ifdef PNG_POWERPC_VSX_FILE
+
+#include <signal.h> /* for sig_atomic_t */
+static int png_have_vsx(png_structp png_ptr);
+#include PNG_POWERPC_VSX_FILE
+
+#else  /* PNG_POWERPC_VSX_FILE */
+#  error "PNG_POWERPC_VSX_FILE undefined: no support for run-time POWERPC VSX checks"
+#endif /* PNG_POWERPC_VSX_FILE */
+#endif /* PNG_POWERPC_VSX_CHECK_SUPPORTED */
+
+#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
+#  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
+#endif
+
+void
+png_init_filter_functions_vsx(png_structp pp, unsigned int bpp)
+{
+   /* The switch statement is compiled in for POWERPC_VSX_API, the call to
+    * png_have_vsx is compiled in for POWERPC_VSX_CHECK. If both are defined
+    * the check is only performed if the API has not set the PowerPC option on
+    * or off explicitly. In this case the check controls what happens.
+    */
+
+#ifdef PNG_POWERPC_VSX_API_SUPPORTED
+   switch ((pp->options >> PNG_POWERPC_VSX) & 3)
+   {
+      case PNG_OPTION_UNSET:
+         /* Allow the run-time check to execute if it has been enabled -
+          * thus both API and CHECK can be turned on.  If it isn't supported
+          * this case will fall through to the 'default' below, which just
+          * returns.
+          */
+#endif /* PNG_POWERPC_VSX_API_SUPPORTED */
+#ifdef PNG_POWERPC_VSX_CHECK_SUPPORTED
+         {
+            static volatile sig_atomic_t no_vsx = -1; /* not checked */
+
+            if (no_vsx < 0)
+               no_vsx = !png_have_vsx(pp);
+
+            if (no_vsx)
+               return;
+         }
+#ifdef PNG_POWERPC_VSX_API_SUPPORTED
+         break;
+#endif
+#endif /* PNG_POWERPC_VSX_CHECK_SUPPORTED */
+
+#ifdef PNG_POWERPC_VSX_API_SUPPORTED
+      default: /* OFF or INVALID */
+         return;
+
+      case PNG_OPTION_ON:
+         /* Option turned on */
+         break;
+   }
+#endif
+
+   /* IMPORTANT: any new internal functions used here must be declared using
+    * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
+    * 'prefix' option to configure works:
+    *
+    *    ./configure --with-libpng-prefix=foobar_
+    *
+    * Verify you have got this right by running the above command, doing a build
+    * and examining pngprefix.h; it must contain a #define for every external
+    * function you add.  (Notice that this happens automatically for the
+    * initialization function.)
+    */
+   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_vsx;
+
+   if (bpp == 3)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_vsx;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_vsx;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth3_vsx;
+   }
+
+   else if (bpp == 4)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_vsx;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_vsx;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth4_vsx;
+   }
+}
+#endif /* PNG_POWERPC_VSX_OPT > 0 */
+#endif /* READ */