When compiling gcc (and binutils) for x86 targets, what is the difference between specifying --target=i386 vs i486 vs i586 etc? How does it affect code generation exactly? As a test I've built toolchains with both i386 and i686, and compiled a program with both. I'm looking for cmov instructions since a 386 wouldn't support those. i386-gcc : no cmov i686-gcc : cmov i386-gcc -march=i686: cmov i686-gcc -march=i386: cmov (!) So it looks like gcc compiled with --target=i686-* is incapable of producing i386 code, and --target=i386-* is the most versatile option for backwards compatibility with older cpus. Are there any disadvantages (reduced optimization, etc) to using an i386-gcc with -march=i686 when compiling for "newer" systems?
