On 07.03.2024 21:54, Oleksii wrote: > On Thu, 2024-03-07 at 21:49 +0100, Oleksii wrote: >> On Thu, 2024-03-07 at 18:14 +0100, Jan Beulich wrote: >>> For plain writes it should at least be "=Qo" then, yes. >> Constraints Q is a machine specific constraint, and I am not sure >> that >> it makes sense to use "=o" only and probably it is a reason why it is >> enough only "r". Does it make sense? > Probably for RISC-V can be used: > RISC-V—config/riscv/constraints.md > ... > A > An address that is held in a general-purpose register. > ...
Just from the description I would have said no, but looking at what "A" actually expands to it is indeed RISC-V's counterpart of Arm's "Q". So yes, this looks like what amo* want to use, and then as a real operand, not just a fake one. > AArch64 family—config/aarch64/constraints.md: > ... > Q > A memory address which uses a single base register with no > offset > ... > Also 'no offset' explains why it was added 'o' constraint for Arm > additionally. I don't think it does. Jan
