[Bug middle-end/29881] union causes inefficient code

["jose dot r dot fonseca at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #6 from jose dot r dot fonseca at gmail dot com  2007-08-07 14:18 -------
Created an attachment (id=14031)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14031&action=view)
Example code

This is the source-code for my example above. To get the assembly run as:

gcc -S -DCASE=0 -O3 -msse2 -o sse2-union-0.s sse2-union.cpp
gcc -S -DCASE=1 -O3 -msse2 -o sse2-union-1.s sse2-union.cpp
gcc -S -DCASE=2 -O3 -msse2 -o sse2-union-2.s sse2-union.cpp
gcc -S -DCASE=3 -O3 -msse2 -o sse2-union-3.s sse2-union.cpp

This was run on (gcc -v):

Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--with-gxx-include-dir=/usr/include/c++/4.1.3 --program-suffix=-4.1
--enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug
--enable-mpfr --enable-checking=release i486-linux-gnu
Thread model: posix
gcc version 4.1.3 20070718 (prerelease) (Debian 4.1.2-14)

But I actually first discovered this in an unofficial build of gcc-4.2 for
MinGW.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29881