[MIR] Implement as casting (Misc cast kind)
#30586
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r? @Aatch (rust_highfive has picked a reviewer for you, use r? to override) |
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r? @arielb1 |
| &format!("unsupported cast: {:?} to {:?}", operand.ty, cast_ty) | ||
| ) | ||
| }; | ||
| OperandValue::Immediate(newval) |
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Not sure if assuming everything is immediate here is correct, but I can’t think of a case where it could be something else.
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Be careful of fat pointers.
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None of the cast cases written out above would handle or produce fat pointers. I’m more concerned with Ref vs Immediate. I.e. can Misc branch be reached with a OperandValue::Ref for castee.
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The discriminant of an OperandValue is supposed to be a function of the operand's type.
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r+ if you add fat-pointer-to-thin-pointer and fat-pointer-to-fat-pointer casts. |
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I added preliminary impl of misc casts from fat-ptr, but I have little idea if it is correct. E.g. currently fat-ptr → fat-ptr is just a no-op, but only because I couldn’t think of a valid fat-ptr → fat-ptr cast which would change LLVM type of the fat-ptr. EDIT: people on IRC helped me to find such a case which resulted in updated PR |
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Ah well, I also want a test that identity casts work (e.g. |
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It's a separate bug. @bors r+ |
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📌 Commit feab2ae has been approved by |
I think that should pretty much conclude all of #29576.
I think that should pretty much conclude all of #29576.