Rollup merge of #100822 - WaffleLapkin:no_offset_question_mark, r=scottmcm

Replace most uses of `pointer::offset` with `add` and `sub`

As PR title says, it replaces `pointer::offset` in compiler and standard library with `pointer::add` and `pointer::sub`. This generally makes code cleaner, easier to grasp and removes (or, well, hides) integer casts.

This is generally trivially correct, `.offset(-constant)` is just `.sub(constant)`, `.offset(usized as isize)` is just `.add(usized)`, etc. However in some cases we need to be careful with signs of things.

r? ````@scottmcm````

_split off from #100746_
This commit is contained in:
Matthias Krüger 2022-08-21 16:54:07 +02:00 committed by GitHub
commit 5a9b11648f

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@ -94,7 +94,7 @@ mod platform {
struct Header(*mut u8);
const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
&mut *(ptr as *mut Header).offset(-1)
&mut *(ptr as *mut Header).sub(1)
}
unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
let aligned = ptr.add(align - (ptr as usize & (align - 1)));