user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Merge pull request #685 from alexcrichton/wams-div128

Browse source 
Use the trifecta div algorithm for 128-bit div on wasm
This commit is contained in:
Trevor Gross 2024-09-05 12:14:05 -04:00 • committed by GitHub
commit 269a7ef042
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 15 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

20
library/compiler-builtins/src/int/specialized_div_rem/mod.rs
View file

@ -136,9 +136,15 @@ fn u64_by_u64_div_rem(duo: u64, div: u64) -> (u64, u64) {
// Whether `trifecta` or `delegate` is faster for 128 bit division depends on the speed at which a
// microarchitecture can multiply and divide. We decide to be optimistic and assume `trifecta` is
// faster if the target pointer width is at least 64.
// faster if the target pointer width is at least 64. Note that this
// implementation is additionally included on WebAssembly despite the typical
// pointer width there being 32 because it's typically run on a 64-bit machine
// that has access to faster 64-bit operations.
#[cfg(all(
not(any(target_pointer_width = "16", target_pointer_width = "32")),
any(
target_family = "wasm",
not(any(target_pointer_width = "16", target_pointer_width = "32")),
),
not(all(not(feature = "no-asm"), target_arch = "x86_64")),
not(any(target_arch = "sparc", target_arch = "sparc64"))
))]
@ -152,10 +158,14 @@ impl_trifecta!(
u128
);
// If the pointer width less than 64, then the target architecture almost certainly does not have
// the fast 64 to 128 bit widening multiplication needed for `trifecta` to be faster.
// If the pointer width less than 64 and this isn't wasm, then the target
// architecture almost certainly does not have the fast 64 to 128 bit widening
// multiplication needed for `trifecta` to be faster.
#[cfg(all(
any(target_pointer_width = "16", target_pointer_width = "32"),
not(any(
target_family = "wasm",
not(any(target_pointer_width = "16", target_pointer_width = "32")),
)),
not(all(not(feature = "no-asm"), target_arch = "x86_64")),
not(any(target_arch = "sparc", target_arch = "sparc64"))
))]