[EMAIL PROTECTED] writes: > > [EMAIL PROTECTED] writes: > > > >> I'm interested in duplicating the immediate predecessor basic block of > >> the > >> EXIT_BLOCK, but this makes the EXIT_BLOCK have 2 predecessors which > >> isn't > >> allowed. Can someone give me some guidances as to how I can insert a > >> bogus block between the two to allow the duplication? > > > > Why can't EXIT_BLOCK have two predecessors? > > > > Ian > > > > From can_duplicate_block_p(): > /* Duplicating fallthru block to exit would require adding a jump and > splitting the real last BB. */ > e = find_edge (bb, EXIT_BLOCK_PTR); > if ( e && (e->flags & EDGE_FALLTHRU)) > return false;
I don't know why that is there. I see that it has been there since the function was written. There may well be a good reason for it. Or not. I don't know. Still, it doesn't follow that EXIT_BLOCK can't have more than one predecessor. Even that code just prevents it from having more than one EDGE_FALLTHRU predecessor. Anyhow, to answer your original question, you should be able to call split_edge to introduce a new basic block between your block and EXIT_BLOCK. Ian
