https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65368
--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Uroš Bizjak from comment #7) > Probably I didn't form the question in the right way - I was trying to point > out, if we also describe BEXTR without unspec (in a similar way as your > proposed patch describes BZHI), then combine will be able to propagate > eventual immediates to the insn, and in this case reduce BEXTR with START=0 > and LEN=n to an AND. To answer my own question: It isn't feasible. BEXTR indeed has weird operand encoding [1], involving "control operand" with special meaning. [1] http://www.felixcloutier.com/x86/BEXTR.html
