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

WÁNG Xuěruì via Phabricator via llvm-commits llvm-commits at lists.llvm.org
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.


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