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Re: Cygwin 32bit: Can't use gcc -mfpmath=sse

On Thu, 10 Sep 2015 13:19:04 +0200, V?clav_Haisman wrote:
On 10 September 2015 at 01:30, HK wrote:
I've just run across this strange behavior on a recent 32bit installation:

 vega> cat hello.c
#include <stdio.h>
int main(int argc, char** argv){
printf("hello world\n");
 vega> gcc -mfpmath=sse hello.c
hello.c:1:0: warning: SSE instruction set disabled, using 387 arithmetics

Does it help to use `-march=native`? My hunch is that this is because
the default CPU type is set to such that does not have SSE.

Yep, that did the trick. Thanks for the suggestion. Now, is this a gcc build
build problem?  The 64bit version doesn't need -march=native and that is on
the same computer.

 #include <stdio.h>

Why is this? I am pretty sure this used to work in the past. On the 64bit
installtion it works just fine.

For reference:

 vega> gcc -v
Using built-in specs.
Target: i686-pc-cygwin
Configured with:
--prefix=/usr --exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc
--docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C
--build=i686-pc-cygwin --host=i686-pc-cygwin --target=i686-pc-cygwin
--without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib
--enable-shared --enable-shared-libgcc --enable-static
--enable-version-specific-runtime-libs --enable-bootstrap
--enable-__cxa_atexit --with-dwarf2 --with-arch=i686 --with-tune=generic
--enable-languages=ada,c,c++,fortran,java,lto,objc,obj-c++ --enable-graphite --enable-threads=posix --enable-libatomic --enable-libgomp --disable-libitm
--enable-libquadmath --enable-libquadmath-support --enable-libssp
--enable-libada --enable-libjava --enable-libgcj-sublibs --disable-java-awt
--disable-symvers --with-ecj-jar=/usr/share/java/ecj.jar --with-gnu-ld
--with-gnu-as --with-cloog-include=/usr/include/cloog-isl
--without-libiconv-prefix --without-libintl-prefix --with-system-zlib
Thread model: posix
gcc version 4.9.3 (GCC)

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