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Auto merge of #96946 - WaffleLapkin:ptr_mask, r=scottmcm

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Add pointer masking convenience functions

This PR adds the following public API:
```rust
impl<T: ?Sized> *const T {
    fn mask(self, mask: usize) -> *const T;
}

impl<T: ?Sized> *mut T {
    fn mask(self, mask: usize) -> *const T;
}

// mod intrinsics
fn mask<T>(ptr: *const T, mask: usize) -> *const T
```
This is equivalent to `ptr.map_addr(|a| a & mask)` but also uses a cool llvm intrinsic.

Proposed in https://github.com/rust-lang/rust/pull/95643#issuecomment-1121562352

cc `@Gankra` `@scottmcm` `@RalfJung`

r? rust-lang/libs-api
This commit is contained in:
bors 2022-08-28 01:34:47 +00:00
commit 1e978a3627
10 changed files with 87 additions and 1 deletions
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compiler/rustc_codegen_llvm/src/intrinsic.rs
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@ -71,6 +71,7 @@ fn get_simple_intrinsic<'ll>(
sym::nearbyintf64 => "llvm.nearbyint.f64",
sym::roundf32 => "llvm.round.f32",
sym::roundf64 => "llvm.round.f64",
sym::ptr_mask => "llvm.ptrmask",
_ => return None,
};
Some(cx.get_intrinsic(llvm_name))