Jamie Prescott <jpre...@yahoo.com> writes: >> Normally gcc will allocate registers in the order they are listed in >> REG_ALLOC_ORDER, which defaults to increasing numeric order. gcc won't >> normally allocate register sparsely. That said, it is quite possible >> for gcc to allocate a register and then discover that it need not be >> allocated. There isn't currently any way to request that gcc tighten up >> the register allocation. That would probably require another >> optimization pass to consistently rename registers when there is a hole >> in the allocation order. > > Yep, usually it allocates compact, but I noticed that when there's some > inline assembly > with ad-hoc register naming, it starts generating holes. > The extra renaming pass, is it something available today?
No. > If not, what is the best spot (in the normal GCC target hooks) to trigger it? > Where the > full insn tree is passed in such hook (if it's not a global)? TARGET_MACHINE_DEPENDENT_REORG. It will be invoked once for each function, and can access and modify the complete RTL insn tree. Ian
