Enable u64 limbs in core::num::bignum
#146277
Conversation
rustbot
added
S-waiting-on-review
|
I’m pretty sure uncommenting this doesn’t actually do anything unless you also update the |
|
Thanks, I wanted to hear something like this, but I might need little bit more explanations about this
Do I have to replace this pub type Digit32 = u32;
define_bignum!(Big32x40: type=Digit32, n=40);And update this name in other places like imports and tests? |
|
I don’t know if I can provide much guidance here. I haven’t touched this code in about ten years and the parts I’ve worked on have almost entirely been replaced by now. The only thing I can tell you is that simply replacing the existing u32 limbs with u64 limbs will probably be a performance regression on 32 bit targets. A straight replacement is probably easier to try out (to see if it gives any performance gains) but a version that can happily be merged will probably have to grapple with using different bignum types based on some |
|
I like your idea with |
|
It used to be used in the slow paths of dec2flt and flt2dec. From a quick code search on GitHub, only flt2dec is still using it. I don’t know off-hand how to find a benchmark that takes that particular code path. |
|
I tried a full replacement locally and saw the extensive fallout in tests and constants. It's a much larger change than I initially thought. Given the scope and the risk of regression on 32-bit, I'll keep this PR minimal and just uncommenting the line to clean up the obsolete comment. The architectural shift to |
| } | ||
|
|
||
| impl_full_ops! { | ||
| u8: add(intrinsics::u8_add_with_overflow), mul/div(u16); |
There was a problem hiding this comment.
Speaking of things being stable‚ it looks like full_mul_add above could just be a call to https://doc.rust-lang.org/nightly/std/primitive.u32.html#method.carrying_mul_add -- which is now stable -- instead of needing to write out the multiplication in $bigty.
Want to make another PR after this one to do that? 🙂
|
Agreed it seems reasonable to just impl the trait for the type -- better than a fixme, at least. @bors r+ rollup |
bors
added
S-waiting-on-bors
Enable `u64` limbs in `core::num::bignum` Since `u128` is stable now, I guess, we can safely add this, not sure if this requires tests or anything cc rust-lang#137887
Enable `u64` limbs in `core::num::bignum` Since `u128` is stable now, I guess, we can safely add this, not sure if this requires tests or anything cc rust-lang#137887
Rollup of 11 pull requests Successful merges: - #146277 (Enable `u64` limbs in `core::num::bignum`) - #146976 (constify basic Clone impls) - #147249 (Do two passes of `handle_opaque_type_uses_next`) - #147266 (fix 2 search graph bugs) - #147468 (Implement fs api set_times and set_times_nofollow) - #147497 (`proc_macro` cleanups (3/N)) - #147594 (std: implement `pal::os::exit` for VEXos) - #147596 (Adjust the Arm targets in CI to reflect latest changes) - #147607 (GVN: Invalidate derefs at loop headers) - #147620 (Avoid redundant UB check in RangeFrom slice indexing) - #147647 (Hide vendoring and copyright in GHA group) r? `@ghost` `@rustbot` modify labels: rollup
Enable `u64` limbs in `core::num::bignum` Since `u128` is stable now, I guess, we can safely add this, not sure if this requires tests or anything cc rust-lang#137887
Enable `u64` limbs in `core::num::bignum` Since `u128` is stable now, I guess, we can safely add this, not sure if this requires tests or anything cc rust-lang#137887
Enable `u64` limbs in `core::num::bignum` Since `u128` is stable now, I guess, we can safely add this, not sure if this requires tests or anything cc rust-lang#137887
Enable `u64` limbs in `core::num::bignum` Since `u128` is stable now, I guess, we can safely add this, not sure if this requires tests or anything cc rust-lang#137887
Rollup of 12 pull requests Successful merges: - #146277 (Enable `u64` limbs in `core::num::bignum`) - #146976 (constify basic Clone impls) - #147249 (Do two passes of `handle_opaque_type_uses_next`) - #147266 (fix 2 search graph bugs) - #147497 (`proc_macro` cleanups (3/N)) - #147546 (Suppress unused_parens for labeled break) - #147548 (Fix ICE for never pattern as closure parameters) - #147594 (std: implement `pal::os::exit` for VEXos) - #147596 (Adjust the Arm targets in CI to reflect latest changes) - #147607 (GVN: Invalidate derefs at loop headers) - #147620 (Avoid redundant UB check in RangeFrom slice indexing) - #147647 (Hide vendoring and copyright in GHA group) r? `@ghost` `@rustbot` modify labels: rollup
…cottmcm Replace manual implementation with `carrying_mul_add` cc rust-lang#146277 (comment) r? scottmcm
…cottmcm Replace manual implementation with `carrying_mul_add` cc rust-lang#146277 (comment) r? scottmcm
…cottmcm Replace manual implementation with `carrying_mul_add` cc rust-lang#146277 (comment) r? scottmcm
…cottmcm Replace manual implementation with `carrying_mul_add` cc rust-lang#146277 (comment) r? scottmcm
Rollup merge of #147666 - Kivooeo:full_mud_add-followup, r=scottmcm Replace manual implementation with `carrying_mul_add` cc #146277 (comment) r? scottmcm
|
Bors hasn't noticed that this was merged. @bors r- |
bors
added
S-waiting-on-author
Replace manual implementation with `carrying_mul_add` cc rust-lang/rust#146277 (comment) r? scottmcm
6 participants
Since
u128is stable now, I guess, we can safely add this, not sure if this requires tests or anythingcc #137887