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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 f48af912ea
1 changed files with 7 additions and 0 deletions
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7
src/intrinsics/mod.rs
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@ -577,6 +577,13 @@ fn codegen_regular_intrinsic_call<'tcx>(
ret.write_cvalue(fx, CValue::by_val(res, base.layout()));
}
sym::ptr_mask => {
intrinsic_args!(fx, args => (ptr, mask); intrinsic);
let ptr = ptr.load_scalar(fx);
let mask = mask.load_scalar(fx);
fx.bcx.ins().band(ptr, mask);
}
sym::transmute => {
intrinsic_args!(fx, args => (from); intrinsic);