contrib/intel/intel_sse.patch

diff --git a/configure.ac b/configure.ac
--- a/configure.ac	2016-02-22 17:24:25.000000000 -0600
+++ b/configure.ac	2016-02-22 17:30:36.949159871 -0600
@@ -1,10 +1,13 @@
 # configure.ac
 
+# Copyright (c) 2016 Google, Inc.
+# Written by Mike Klein and Matt Sarett
+# Derived from the ARM supporting code in libpng/configure.ac, which was
 # Copyright (c) 2004-2015 Glenn Randers-Pehrson
 # Last changed in libpng 1.6.22 [(PENDING RELEASE)]
 
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
 # and license in png.h
 
 dnl Process this file with autoconf to produce a configure script.
@@ -316,16 +319,50 @@ AC_ARG_ENABLE([arm-neon],
 
 AM_CONDITIONAL([PNG_ARM_NEON],
    [test "$enable_arm_neon" != 'no' &&
     case "$host_cpu" in
       arm*|aarch64*) :;;
       *)    test "$enable_arm_neon" != '';;
     esac])
 
+# INTEL
+# =====
+#
+# INTEL SSE (SIMD) support.
+
+AC_ARG_ENABLE([intel-sse],
+   AS_HELP_STRING([[[--enable-intel-sse]]],
+      [Enable Intel SSE optimizations: =no/off, yes/on:]
+      [no/off: disable the optimizations;]
+      [yes/on: enable the optimizations.]
+      [If not specified: determined by the compiler.]),
+   [case "$enableval" in
+      no|off)
+         # disable the default enabling:
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
+                   [Disable Intel SSE optimizations])
+         # Prevent inclusion of the assembler files below:
+         enable_intel_sse=no;;
+      yes|on)
+         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
+                   [Enable Intel SSE optimizations]);;
+      *)
+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
+   esac])
+
+# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
+# or where Intel optimizations were explicitly requested (this allows a
+# fallback if a future host CPU does not match 'x86*')
+AM_CONDITIONAL([PNG_INTEL_SSE],
+   [test "$enable_intel_sse" != 'no' &&
+    case "$host_cpu" in
+      i?86|x86_64) :;;
+      *)    test "$enable_intel_sse" != '';;
+    esac])
 AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
 
 # Config files, substituting as above
 AC_CONFIG_FILES([Makefile libpng.pc:libpng.pc.in])
 AC_CONFIG_FILES([libpng-config:libpng-config.in],
    [chmod +x libpng-config])
 
 AC_OUTPUT
diff --git a/Makefile.am b/Makefile.am
--- a/Makefile.am	2016-02-22 17:24:24.000000000 -0600
+++ b/Makefile.am	2016-02-22 17:32:18.387223996 -0600
@@ -1,10 +1,13 @@
 # Makefile.am, the source file for Makefile.in (and hence Makefile), is
 #
+# Copyright (c) 2016 Google, Inc.
+# Written by Mike Klein and Matt Sarett
+# Derived from the ARM supporting code in libpng/configure.ac, which was
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
 # Last changed in libpng 1.6.22 [(PENDING RELEASE)]
 #
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
 # and license in png.h
 
 PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
@@ -83,16 +86,20 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SO
 	pngset.c pngtrans.c pngwio.c pngwrite.c pngwtran.c pngwutil.c\
 	png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa
 
 if PNG_ARM_NEON
 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
 	arm/filter_neon.S arm/filter_neon_intrinsics.c
 endif
 
+if PNG_INTEL_SSE
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
+    contrib/intel/filter_sse2_intrinsics.c
+endif
 nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
 
 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
 	-version-number @PNGLIB_MAJOR@@PNGLIB_MINOR@:@PNGLIB_RELEASE@:0
 
 if HAVE_LD_VERSION_SCRIPT
 #   Versioned symbols and restricted exports
 if HAVE_SOLARIS_LD