[PATCH] D98789: [PEI] add dwarf information for stack probe

[YangKeao via Phabricator via llvm-commits]

YangKeao added a comment.

> A care must be taken to not overwrite the arguments as well. For instance on SysV x86_64 ABI `rdi`, `rsi`, `rdx`, `rcx`, `r8`, `r9` are used to pass in integer arguments. For functions with a small number of arguments one of these could be reused, but if a function happens to use all of them, unconditional use of `rdx` would clobber the argument.

Nice catch! After eliminating `RCX`, `RDX` from the selections, it seems that the only possible "always correct" choice is `RAX` (being used as the return value doesn't bother).

> See `createVirtualRegister`.

Thanks. I have seen some usage of this function. It seems that there isn't any suitable `RegClass` for this situation (Dwarf Reg Class is not generated). Should I create one by myself?


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