> If the branch edge destination is a basic block with only a direct
> sibcall, change the jcc target to the sibcall target, decrement the
> destination basic block entry label use count and redirect the edge
> to the exit basic block. Call delete_unreachable_blocks to delete
> the unreachable basic blocks at the end if edges are redirected.
Its hard to believe this needs a new pass. Could the existing middle end
tail call code handle it somehow?
Each new pass makes the compiler a little slower.
> + FOR_EACH_BB_FN (bb, cfun)
> + {
> + FOR_BB_INSNS (bb, insn)
> + {
> + if (!JUMP_P (insn))
> + continue;
Instead of searching all basic blocks this could search from the end
simllar to tree tailcall
> + /* opt_pass methods: */
> + bool gate (function *) final override
> + {
> + return optimize;
Thia needs to depend on the existing tail call options. I would also
add a new option because it is highly likely to break some unwinders
and static asm analysis tools like Linux objtool. Does the gcc unwinding
or gdb calltrace still work?
Andi
