debuginfo: Use TypeIdHasher for generating global debuginfo type IDs. #37336
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r? @eddyb (rust_highfive has picked a reviewer for you, use r? to override) |
| } | ||
| fn write_usize(&mut self, i: usize) { | ||
| self.inner.write_u64(i as u64) | ||
| self.inner.write_u64((i as u64).to_le()) |
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This, and isize should probably not have the to_le().
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Why? That would be true if they were calling self.write_u64 and not self.inner.write_u64.
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Really? I'm not sure I follow why (they call the inner write_u64 at least rather than the outer one)... Could you elaborate?
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Ahhh, didn't read that code carefully enough 😞 I still remembered that usize would delegate to u64 and didn't expect to go directly to the inner.
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| } | ||
| fn write_usize(&mut self, i: usize) { | ||
| self.inner.write_u64(i as u64) | ||
| self.inner.write_u64((i as u64).to_le()) |
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Why? That would be true if they were calling self.write_u64 and not self.inner.write_u64.
src/librustc/ty/util.rs
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| struct WidenUsizeHasher<H> { | ||
| // | ||
| // The same goes for endianess: We always convert multi-byte integers to little | ||
| // endian before hashing. |
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Can we turn this into a doc comment? Maybe even make it public, seems useful elsewhere.
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Fixed the failing test case. |
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@bors r+ |
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📌 Commit 025b27d has been approved by |
…, r=eddyb debuginfo: Use TypeIdHasher for generating global debuginfo type IDs. The only requirement for debuginfo type IDs is that they are globally unique. The `TypeIdHasher` (which is used for `std::intrinsic::type_id()` provides that, so we can get rid of some redundancy by re-using it for debuginfo. Values produced by the `TypeIdHasher` are also more stable than the current `UniqueTypeId` generation algorithm produces -- these incorporate the `NodeId`s, which is not good for incremental compilation. @alexcrichton @eddyb : Could you take a look at the endianess adaptations that I made to the `TypeIdHasher`? Also, are we sure that a 64 bit hash is wide enough for something that is supposed to be globally unique? For debuginfo I'm using 160 bits to make sure that we don't run into conflicts there.
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The only requirement for debuginfo type IDs is that they are globally unique. The
TypeIdHasher(which is used forstd::intrinsic::type_id()provides that, so we can get rid of some redundancy by re-using it for debuginfo. Values produced by theTypeIdHasherare also more stable than the currentUniqueTypeIdgeneration algorithm produces -- these incorporate theNodeIds, which is not good for incremental compilation.@alexcrichton @eddyb : Could you take a look at the endianess adaptations that I made to the
TypeIdHasher?Also, are we sure that a 64 bit hash is wide enough for something that is supposed to be globally unique? For debuginfo I'm using 160 bits to make sure that we don't run into conflicts there.