configure: test for -msse2

+ add a WEBP_HAVE_SSE2 to dsp.h

not all 32-bit toolchain configurations will have sse2 enabled by
default

Change-Id: I7c675e511581f93cf55c79f960fa7efa2df4987e

configure.ac

@@ -67,6 +67,12 @@ AS_IF([test -n "$AVX2_FLAGS"], [
             [Set to 1 if AVX2 is supported])])
 AC_SUBST([AVX2_FLAGS])
 
+TEST_AND_ADD_CFLAGS([SSE2_FLAGS], [-msse2])
+AS_IF([test -n "$SSE2_FLAGS"], [
+  AC_DEFINE(WEBP_HAVE_SSE2, [1],
+            [Set to 1 if SSE2 is supported])])
+AC_SUBST([SSE2_FLAGS])
+
 dnl === CLEAR_LIBVARS([var_pfx])
 dnl ===   Clears <var_pfx>_{INCLUDES,LIBS}.
 AC_DEFUN([CLEAR_LIBVARS], [$1_INCLUDES=""; $1_LIBS=""])

src/dsp/Makefile.am

@@ -1,5 +1,6 @@
 AM_CPPFLAGS = -I$(top_srcdir)/src
 noinst_LTLIBRARIES = libwebpdsp.la libwebpdsp_avx2.la
+noinst_LTLIBRARIES += libwebpdsp_sse2.la libwebpdspdecode_sse2.la
 
 if BUILD_LIBWEBPDECODER
   noinst_LTLIBRARIES += libwebpdspdecode.la
@@ -15,34 +16,43 @@ COMMON_SOURCES += dec.c
 COMMON_SOURCES += dec_clip_tables.c
 COMMON_SOURCES += dec_mips32.c
 COMMON_SOURCES += dec_neon.c
-COMMON_SOURCES += dec_sse2.c
 COMMON_SOURCES += dsp.h
 COMMON_SOURCES += lossless.c
 COMMON_SOURCES += lossless.h
 COMMON_SOURCES += lossless_mips32.c
 COMMON_SOURCES += lossless_neon.c
-COMMON_SOURCES += lossless_sse2.c
 COMMON_SOURCES += neon.h
 COMMON_SOURCES += upsampling.c
 COMMON_SOURCES += upsampling_neon.c
-COMMON_SOURCES += upsampling_sse2.c
 COMMON_SOURCES += yuv.c
 COMMON_SOURCES += yuv.h
 COMMON_SOURCES += yuv_mips32.c
-COMMON_SOURCES += yuv_sse2.c
-COMMON_SOURCES += yuv_tables_sse2.h
 
 ENC_SOURCES =
 ENC_SOURCES += enc.c
 ENC_SOURCES += enc_mips32.c
 ENC_SOURCES += enc_neon.c
-ENC_SOURCES += enc_sse2.c
 
 libwebpdsp_avx2_la_SOURCES =
 libwebpdsp_avx2_la_SOURCES += enc_avx2.c
 libwebpdsp_avx2_la_CPPFLAGS = $(libwebpdsp_la_CPPFLAGS)
 libwebpdsp_avx2_la_CFLAGS = $(AM_CFLAGS) $(AVX2_FLAGS)
 
+libwebpdspdecode_sse2_la_SOURCES =
+libwebpdspdecode_sse2_la_SOURCES += dec_sse2.c
+libwebpdspdecode_sse2_la_SOURCES += lossless_sse2.c
+libwebpdspdecode_sse2_la_SOURCES += upsampling_sse2.c
+libwebpdspdecode_sse2_la_SOURCES += yuv_sse2.c
+libwebpdspdecode_sse2_la_SOURCES += yuv_tables_sse2.h
+libwebpdspdecode_sse2_la_CPPFLAGS = $(libwebpdsp_sse2_la_CPPFLAGS)
+libwebpdspdecode_sse2_la_CFLAGS = $(libwebpdsp_sse2_la_CFLAGS)
+
+libwebpdsp_sse2_la_SOURCES =
+libwebpdsp_sse2_la_SOURCES += enc_sse2.c
+libwebpdsp_sse2_la_CPPFLAGS = $(libwebpdsp_la_CPPFLAGS)
+libwebpdsp_sse2_la_CFLAGS = $(AM_CFLAGS) $(SSE2_FLAGS)
+libwebpdsp_sse2_la_LIBADD = libwebpdspdecode_sse2.la
+
 libwebpdsp_la_SOURCES = $(COMMON_SOURCES) $(ENC_SOURCES)
 
 noinst_HEADERS =
@@ -51,11 +61,12 @@ noinst_HEADERS += ../webp/decode.h
 
 libwebpdsp_la_CPPFLAGS = $(USE_EXPERIMENTAL_CODE) $(USE_SWAP_16BIT_CSP)
 libwebpdsp_la_LDFLAGS = -lm
-libwebpdsp_la_LIBADD = libwebpdsp_avx2.la
+libwebpdsp_la_LIBADD = libwebpdsp_avx2.la libwebpdsp_sse2.la
 
 if BUILD_LIBWEBPDECODER
   libwebpdspdecode_la_SOURCES = $(COMMON_SOURCES)
 
   libwebpdspdecode_la_CPPFLAGS = $(libwebpdsp_la_CPPFLAGS)
   libwebpdspdecode_la_LDFLAGS = $(libwebpdsp_la_LDFLAGS)
+  libwebpdspdecode_la_LIBADD = libwebpdspdecode_sse2.la
 endif

src/dsp/dsp.h

@@ -40,7 +40,11 @@ extern "C" {
 #define WEBP_MSC_SSE2  // Visual C++ SSE2 targets
 #endif
 
-#if defined(__SSE2__) || defined(WEBP_MSC_SSE2)
+// WEBP_HAVE_* are used to indicate the presence of the instruction set in dsp
+// files without intrinsics, allowing the corresponding Init() to be called.
+// Files containing intrinsics will need to be built targeting the instruction
+// set so should succeed on one of the earlier tests.
+#if defined(__SSE2__) || defined(WEBP_MSC_SSE2) || defined(WEBP_HAVE_SSE2)
 #define WEBP_USE_SSE2
 #endif