core: add instrinsics for llvm.expect.i8-i64 #22883
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r? @aturon (rust_highfive has picked a reviewer for you, use r? to override) |
| /// Inform the optimizer that `expected_val` is expected | ||
| /// (the most probable) value of val. | ||
| #[cfg(stage0)] | ||
| pub unsafe fn expect8(val: u8, _expected_val: u8) -> u8 { |
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I... expect... these aren't actually necessary to do the bootstrap?
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I don't follow? Before i added cfg(stage0) versions, it complained during stage0 that these intrinsics weren't known by the compiler.
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These functions aren't called during the bootstrap, so you can have the FFI declarations be #[cfg(not(stage0))] and just omit these altogether. (I.e. have core::intrinsics::expect* not exist in stage0 at all.)
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Oh I see what you mean.
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Currently we are trying to hide the In the past we've been ok adding these form of intrinsics if they're directly used in the standard library and provide tangible benefits. Exposing them as a public API, however, would require an RFC in any case. For now though because these are not used internally and also not exposed through a stable interface, I'm going to close this. I also think that #20579 should live in the RFC repo instead of this repo as it's a general feature request, I'll see if can't get it moved over. Thanks for the PR though! |
Closes #20579