https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82735
--- Comment #9 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Richard Biener from comment #4) > Indeed as far as I understand an unspec volatile isn't sth clobbering > registers (not even memory?!). The insn is missing inputs/outputs > (we might be able to model that lowparts are preserved). Since the instruction operates on the whole pack (8 or 16 SSE registers), this approach will introduce uninitialized uses, and will clobber the whole register pack. Since SSE registers are callee-saved this means all registers will be saved in function prologue and restored in the epilogue.
