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Rollup merge of #96935 - thomcc:atomicptr-strict-prov, r=dtolnay

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Allow arithmetic and certain bitwise ops on AtomicPtr

This is mainly to support migrating from `AtomicUsize`, for the strict provenance experiment.

This is a pretty dubious set of APIs, but it should be sufficient to allow code that's using `AtomicUsize` to manipulate a tagged pointer atomically. It's under a new feature gate, `#![feature(strict_provenance_atomic_ptr)]`, but I'm not sure if it needs its own tracking issue. I'm happy to make one, but it's not clear that it's needed.

I'm unsure if it needs changes in the various non-LLVM backends. Because we just cast things to integers anyway (and were already doing so), I doubt it.

API change proposal: https://github.com/rust-lang/libs-team/issues/60

Fixes #95492
This commit is contained in:
Guillaume Gomez 2022-07-06 20:43:23 +02:00 • committed by GitHub
commit 4755173cf6
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4 changed files with 428 additions and 3 deletions
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4
compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
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@ -513,9 +513,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
};
let ty = substs.type_at(0);
if int_type_width_signed(ty, bx.tcx()).is_some()
|| (ty.is_unsafe_ptr() && op == "xchg")
{
if int_type_width_signed(ty, bx.tcx()).is_some() || ty.is_unsafe_ptr() {
let mut ptr = args[0].immediate();
let mut val = args[1].immediate();
if ty.is_unsafe_ptr() {