On Sat, Apr 11, 2020 at 4:28 PM Sasha Krassovsky via Gcc <gcc@gcc.gnu.org> wrote: > I’m currently modifying the RISC-V backend for a manycore processor where > each core is connected over a network. Each core has a local scratchpad > memory, but can also read and write other cores’ scratchpads. I’d like to add > an attribute to give a hint to the optimizer about which loads will be remote > and therefore longer latency than others.
GCC has support for the proposed named address space extension to the ISO C standard. You may be able to use this instead of defining your own attributes. I don't know if this helps with the rtx cost calculation though. This is mostly about support for more than one address space. See "Named Address Spaces" in the gcc internals docs, and the *_ADDR_SPACE_* stuff in the sources. The problem may be one similar to what Alan Modra mentioned. I would suggest stepping through the cost calculation code in a debugger to see what is happening. Jim
