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.
| 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.
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.