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scrutinize hash functions: << precedence often misused #1267

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nikomatsakis opened this issue Dec 7, 2011 · 1 comment
Closed

scrutinize hash functions: << precedence often misused #1267

nikomatsakis opened this issue Dec 7, 2011 · 1 comment

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@nikomatsakis
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I found that many hash functions in rustc follow this template:

ret foo << 16u + bar;

but by the order of precedence this yields foo << (16u + bar), almost certainly not what was intended. This interacts quite poorly with our hash tables which prefer low-order bits to not be all 0. We need to search through the code and check for similar problems, then close this bug.
@nikomatsakis
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Fixed in @6c95e40

bjorn3 pushed a commit to bjorn3/rust that referenced this issue Aug 24, 2022
@afonso360
Use native scalar fma instruction (rust-lang#1267)
48c45c4 
Cranelift 0.87 now supports lowering `fma` as a libcall on x86 [0].
With 0.88 enabling the native x86 instruction under the `has_fma` flag.

aarch64 and s390x already support this as a native instruction, so it's
nice that we emit it for those.

We can't lower the SIMD version using the `fma` instruction since the
lowering can fail if the x86 `has_fma` flag is not enabled. Cranelift
doesn't yet know how to fallback for these cases

[0]: bytecodealliance/wasmtime@709716b
celinval pushed a commit to celinval/rust-dev that referenced this issue Jun 4, 2024
@zhassan-aws
Create a performance test suite and add s2n-quic as a test (rust-lang…
f711e7a 
…#1267)

* Add s2n-quic as a submodule

* Add a script for running performance tests

* Add a CI workflow for running performance tests
Kobzol pushed a commit to Kobzol/rust that referenced this issue Dec 30, 2024
@richkadel
Update LLVM coverage mapping format version supported by rustc (rust-…
c7be982 
…lang#1267)

rust-lang#91207 updates the coverage mapping format to Version 5 or
6, depending on the built-in version of LLVM (12 or 13, respectively).

This change updates the dev guide to match the recent changes.
bors pushed a commit to rust-lang-ci/rust that referenced this issue Jan 2, 2025
@richkadel
Update LLVM coverage mapping format version supported by rustc (rust-…
d6f4a6b 
…lang#1267)

rust-lang#91207 updates the coverage mapping format to Version 5 or
6, depending on the built-in version of LLVM (12 or 13, respectively).

This change updates the dev guide to match the recent changes.
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@nikomatsakis