On 10/15/2017 02:12 AM, Andrew Haley wrote: > On 14/10/17 11:42, Claudio Eterno wrote: >> I've some doubts on this: >> >> "stack-based architectures are difficult to accommodate as well" >> >> Can someone explain better this? >> If I remember well the C uses the stack for local variable storage, >> does he refer to those architectures which are completely stack >> oriented (GPR not present)? > > This isn't about stack frames. This is about machines such as the > Burroughs B-5500 and its descendants (e.g. Novix) which use > zero-operand instructions. These take operands from the stack and > return the results there. GCC assumes that instructions use registers > for source and destination operands. (Usually, anyway.) It would be > possible to write a pass which turned register-register operations > into stack code, but maybe the code quality wouldn't be great. Well, we have that for the x87 FP unit which is stack based. And, yes, the code isn't great. jeff
