With the upcoming Intel APX extension, Intel processors will finally gain 32 general-purpose registers and three-operand arithmetic, see
https://www.intel.com/content/www/us/en/developer/articles/technical/advanced-performance-extensions-apx.html Intel recommends to have the new registers as caller-saved for compatibility with current calling conventions. If I understand this correctly, this is required for exception unwinding, but not if the function called is __attribute__((nothrow)). Since Fortran tends to use a lot of registers for its array descriptors, and also tends to call nothrow functions (all Fortran functions, and all Fortran intrinsics, such as sin/cos/etc) a lot, it could profit from making some of the new registers callee-saved, to save some spills at function calls. What are the thoughts on it? Is a modification to the ps-ABI already in the works, and how would it treat this case? Best regards Thomas
