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rust/compiler/rustc_monomorphize/src
bors 1559dd2dbf Auto merge of #118770 - saethlin:fix-inline-never-uses, r=nnethercote
Fix cases where std accidentally relied on inline(never)

This PR increases the power of `-Zcross-crate-inline-threshold=always` so that it applies through `#[inline(never)]`. Note that though this is called "cross-crate-inlining" in this case especially it is _just_ lazy per-CGU codegen. The MIR inliner and LLVM still respect the attribute as much as they ever have.

Trying to bootstrap with the new `-Zcross-crate-inline-threshold=always` change revealed two bugs:

We have special intrinsics `assert_inhabited`, `assert_zero_valid`, and `assert_mem_uniniitalized_valid` which codegen backends will lower to nothing or a call to `panic_nounwind`.  Since we may not have any call to `panic_nounwind` in MIR but emit one anyway, we need to specially tell `MirUsedCollector` about this situation.

`#[lang = "start"]` is special-cased already so that `MirUsedCollector` will collect it, but then when we make it cross-crate-inlinable it is only assigned to a CGU based on whether `MirUsedCollector` saw a call to it, which of course we didn't.

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I started looking into this because https://github.com/rust-lang/rust/pull/118683 revealed a case where we were accidentally relying on a function being `#[inline(never)]`, and cranking up cross-crate-inlinability seems like a way to find other situations like that.

r? `@nnethercote` because I don't like what I'm doing to the CGU partitioning code here but I can't come up with something much better
2023-12-15 04:54:14 +00:00
..
collector.rs Fix cases where std accidentally relied on inline(never) 2023-12-14 08:30:36 -05:00
errors.rs Remove UnknownPartitionStrategy error. 2023-10-18 14:42:58 +11:00
lib.rs Use rustc_fluent_macro::fluent_messages! directly. 2023-11-26 08:38:40 +11:00
partitioning.rs Auto merge of #118770 - saethlin:fix-inline-never-uses, r=nnethercote 2023-12-15 04:54:14 +00:00
polymorphize.rs merge DefKind::Coroutine into DefKind::Closure 2023-11-26 21:05:08 +08:00
util.rs subst -> instantiate 2023-09-26 09:37:55 +02:00