-msse3 is only available on x86 architectures

[rsekman]

The library can't be built as-is on AArch64 or other non-x86 architectures because of the -msse3 flag in Makefile.am. This flag is only available for x86. The build system should check the host architecture to determine if this flag should be used. I don't understand autotools very well but from what I've gathered such a check would need to take place in configure.ac of the main project, something like:

index 66faaa09e..93cf931e7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -30,6 +30,7 @@ test "$prefix" = NONE && prefix=/usr/local
 case "$host" in
   i686-apple-*)
     AC_DEFINE(ARCH_X86_32, 1, [architecture is x86 on OSX])
+    SSE_FLAGS="-msse3"
     LIB="static-deps/lib-x86-32-apple"
     YASM_FLAGS="-f macho32 -D ARCH_X86_32 -m x86 -DPREFIX"
     APE_USE_YASM=yes
@@ -37,6 +38,7 @@ case "$host" in
     ;;
   x86_64-apple-*)
     AC_DEFINE(ARCH_X86_64, 1, [architecture is x86_64 on OSX])
+    SSE_FLAGS="-msse3"
     LIB="static-deps/lib-x86-64-apple"
     YASM_FLAGS="-f macho64 -D ARCH_X86_64 -m amd64 -DPIC -DPREFIX"
     APE_USE_YASM=yes
@@ -44,12 +46,14 @@ case "$host" in
     ;;
   i386-*-* | i486-*-* | i586-*-* | i686-*-* | i86pc-*-*)
     AC_DEFINE(ARCH_X86_32, 1, [architecture is x86])
+    SSE_FLAGS="-msse3"
     LIB="static-deps/lib-x86-32"
     YASM_FLAGS="-f elf -D ARCH_X86_32 -m x86"
     APE_USE_YASM=yes
     ;;
   x86_64-*-* | amd64-*-*)
     AC_DEFINE(ARCH_X86_64, 1, [architecture is x86_64])
+    SSE_FLAGS="-msse3"

and a corresponding change in Makefile.am here:

diff --git a/Makefile.am b/Makefile.am
index 8ce4dcc..b2807f5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -4,5 +4,5 @@ EXTRA_DIST = COPYING $(ppsimdpath)/ppsimd-license.txt
 pkglib_LTLIBRARIES = ddb_dsp_libretro.la
 ddb_dsp_libretro_la_SOURCES = libretro.cpp ppsimd/ppsimd.h sinc_resampler.h
 ddb_dsp_libretro_la_LDFLAGS = -module -avoid-version
-ddb_dsp_libretro_la_CXXFLAGS = $(CFLAGS) -msse3 -std=c++11 -I@top_srcdir@/include
+ddb_dsp_libretro_la_CXXFLAGS = $(CFLAGS) $(SSE_FLAGS) -std=c++11 -I@top_srcdir@/include
 endif