1diff --git a/configure.ac b/configure.ac
2--- a/configure.ac	2016-08-29 11:46:27.000000000 -0400
3+++ b/configure.ac	2016-08-29 16:57:03.866355018 -0400
4@@ -386,16 +386,51 @@ AC_ARG_ENABLE([mips-msa],
5 # future host CPU does not match 'mips*')
6
7 AM_CONDITIONAL([PNG_MIPS_MSA],
8    [test "$enable_mips_msa" != 'no' &&
9     case "$host_cpu" in
10       mipsel*|mips64el*) :;;
11     esac])
12
13+# INTEL
14+# =====
15+#
16+# INTEL SSE (SIMD) support.
17+
18+AC_ARG_ENABLE([intel-sse],
19+   AS_HELP_STRING([[[--enable-intel-sse]]],
20+      [Enable Intel SSE optimizations: =no/off, yes/on:]
21+      [no/off: disable the optimizations;]
22+      [yes/on: enable the optimizations.]
23+      [If not specified: determined by the compiler.]),
24+   [case "$enableval" in
25+      no|off)
26+         # disable the default enabling:
27+         AC_DEFINE([PNG_INTEL_SSE_OPT], [0],
28+                   [Disable Intel SSE optimizations])
29+         # Prevent inclusion of the assembler files below:
30+         enable_intel_sse=no;;
31+      yes|on)
32+         AC_DEFINE([PNG_INTEL_SSE_OPT], [1],
33+                   [Enable Intel SSE optimizations]);;
34+      *)
35+         AC_MSG_ERROR([--enable-intel-sse=${enable_intel_sse}: invalid value])
36+   esac])
37+
38+# Add Intel specific files to all builds where the host_cpu is Intel ('x86*')
39+# or where Intel optimizations were explicitly requested (this allows a
40+# fallback if a future host CPU does not match 'x86*')
41+AM_CONDITIONAL([PNG_INTEL_SSE],
42+   [test "$enable_intel_sse" != 'no' &&
43+    case "$host_cpu" in
44+      i?86|x86_64) :;;
45+      *)    test "$enable_intel_sse" != '';;
46+    esac])
47+
48 AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
49
50 # Config files, substituting as above
51 AC_CONFIG_FILES([Makefile libpng.pc:libpng.pc.in])
52 AC_CONFIG_FILES([libpng-config:libpng-config.in],
53    [chmod +x libpng-config])
54
55 AC_OUTPUT
56diff --git a/Makefile.am b/Makefile.am
57--- a/Makefile.am	2016-08-29 11:46:27.000000000 -0400
58+++ b/Makefile.am	2016-08-29 16:57:45.955528215 -0400
59@@ -97,16 +97,21 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SO
60 	arm/filter_neon.S arm/filter_neon_intrinsics.c
61 endif
62
63 if PNG_MIPS_MSA
64 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += mips/mips_init.c\
65 	mips/filter_msa_intrinsics.c
66 endif
67
68+if PNG_INTEL_SSE
69+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += contrib/intel/intel_init.c\
70+    contrib/intel/filter_sse2_intrinsics.c
71+endif
72+
73 nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
74
75 libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
76 	-version-number @PNGLIB_MAJOR@@PNGLIB_MINOR@:@PNGLIB_RELEASE@:0
77
78 if HAVE_LD_VERSION_SCRIPT
79 #   Versioned symbols and restricted exports
80 if HAVE_SOLARIS_LD
81diff --git a/pngpriv.h b/pngpriv.h
82--- debug16/pngpriv.h	2016-08-30 10:46:36.000000000 -0400
83+++ libpng16/pngpriv.h	2016-08-30 11:57:25.672280202 -0400
84@@ -185,16 +185,52 @@
85 #ifndef PNG_MIPS_MSA_OPT
86 #  if defined(__mips_msa) && (__mips_isa_rev >= 5) && defined(PNG_ALIGNED_MEMORY_SUPPORTED)
87 #     define PNG_MIPS_MSA_OPT 2
88 #  else
89 #     define PNG_MIPS_MSA_OPT 0
90 #  endif
91 #endif
92
93+#ifndef PNG_INTEL_SSE_OPT
94+#   ifdef PNG_INTEL_SSE
95+      /* Only check for SSE if the build configuration has been modified to
96+       * enable SSE optimizations.  This means that these optimizations will
97+       * be off by default.  See contrib/intel for more details.
98+       */
99+#     if defined(__SSE4_1__) || defined(__AVX__) || defined(__SSSE3__) || \
100+       defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
101+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
102+#         define PNG_INTEL_SSE_OPT 1
103+#      endif
104+#   endif
105+#endif
106+
107+#if PNG_INTEL_SSE_OPT > 0
108+#   ifndef PNG_INTEL_SSE_IMPLEMENTATION
109+#      if defined(__SSE4_1__) || defined(__AVX__)
110+          /* We are not actually using AVX, but checking for AVX is the best
111+             way we can detect SSE4.1 and SSSE3 on MSVC.
112+          */
113+#         define PNG_INTEL_SSE_IMPLEMENTATION 3
114+#      elif defined(__SSSE3__)
115+#         define PNG_INTEL_SSE_IMPLEMENTATION 2
116+#      elif defined(__SSE2__) || defined(_M_X64) || defined(_M_AMD64) || \
117+       (defined(_M_IX86_FP) && _M_IX86_FP >= 2)
118+#         define PNG_INTEL_SSE_IMPLEMENTATION 1
119+#      else
120+#         define PNG_INTEL_SSE_IMPLEMENTATION 0
121+#      endif
122+#   endif
123+
124+#   if PNG_INTEL_SSE_IMPLEMENTATION > 0
125+#      define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_sse2
126+#   endif
127+#endif
128+
129 #if PNG_MIPS_MSA_OPT > 0
130 #  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_msa
131 #  ifndef PNG_MIPS_MSA_IMPLEMENTATION
132 #     if defined(__mips_msa)
133 #        if defined(__clang__)
134 #        elif defined(__GNUC__)
135 #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
136 #              define PNG_MIPS_MSA_IMPLEMENTATION 2
137@@ -1232,16 +1268,31 @@ PNG_INTERNAL_FUNCTION(void,png_read_filt
138 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
139     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
140 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
141     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
142 PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_msa,(png_row_infop
143     row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
144 #endif
145
146+#if PNG_INTEL_SSE_IMPLEMENTATION > 0
147+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub3_sse2,(png_row_infop
148+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
149+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_sub4_sse2,(png_row_infop
150+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
151+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg3_sse2,(png_row_infop
152+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
153+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_sse2,(png_row_infop
154+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
155+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_sse2,(png_row_infop
156+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
157+PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth4_sse2,(png_row_infop
158+    row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
159+#endif
160+
161 /* Choose the best filter to use and filter the row data */
162 PNG_INTERNAL_FUNCTION(void,png_write_find_filter,(png_structrp png_ptr,
163     png_row_infop row_info),PNG_EMPTY);
164
165 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
166 PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
167    png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
168    /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
169@@ -1967,16 +2018,21 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_O
170 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
171    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
172 #endif
173
174 #if PNG_MIPS_MSA_OPT > 0
175 PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_msa,
176    (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
177 #endif
178+
179+#  if PNG_INTEL_SSE_IMPLEMENTATION > 0
180+PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_sse2,
181+   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
182+#  endif
183 #endif
184
185 PNG_INTERNAL_FUNCTION(png_uint_32, png_check_keyword, (png_structrp png_ptr,
186    png_const_charp key, png_bytep new_key), PNG_EMPTY);
187
188 /* Maintainer: Put new private prototypes here ^ */
189
190 #include "pngdebug.h"
191