[PATCH] D140685: [LoongArch] Add intrinsics for MOVFCSR2GR and MOVGR2FCSR instructions

Tue Jan 3 02:37:30 PST 2023

xen0n accepted this revision.
xen0n added a comment.

In D140685#4017381 <https://reviews.llvm.org/D140685#4017381>, @xen0n wrote:

>> MOVGR2FCSR modifies the value of the software writable field
>> corresponding to the FCSR (floating-point control and status
>> register) fcsr according to the value of the lower 32 bits of
>> the GR (general purpose register) rj.
>
> The description of `movgr2fcsr` is incorrect, it implies `GPR[rj]`is read, but in fact it's only the //`ui5` immediate in `rj` slot//, i.e. `FCSR[rj]`. I didn't look very closely but the test case changes seem good.

On a closer look it turns out the description is correct after all, the description is very much non-intuitive (uses just `fcsr` without any position marker) so I've mistaken the GPR operand for the FCSR slot. This is very unfortunate but luckily users of the intrinsics won't have to think about it.

Repository:
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  https://reviews.llvm.org/D140685/new/

https://reviews.llvm.org/D140685