http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50829
--- Comment #10 from Marc Glisse <glisse at gcc dot gnu.org> 2012-12-01 19:50:28 UTC --- Created attachment 28846 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28846 Use subreg Hmm, I don't understand why we use UNSPEC_CAST. I tried the attached patch to use a subreg instead. It passed bootstrap+testsuite and generates optimal code for the testcase of this PR. So, any idea what advantage the unspec has over a subreg? And if none, what is the best way to use a subreg?