Rust: Fix bad join #21180
Merged
Rust: Fix bad join #21180
+3
−2
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Before
```
Evaluated relational algebra for predicate _ElementImpl::Impl::MacroExpansion::isAttributeMacroExpansionSourceLocation/2#3429148c_Locatable::Lo__#antijoin_rhs@9f4aa4rk with tuple counts:
5127263380 ~4% {3} r1 = JOIN `_AstNodeImpl::Impl::AstNode#22e758cf_ElementImpl::Impl::MacroExpansion::getATokenTreeNode/1#a2df59a3__#shared` WITH `ElementImpl::Impl::MacroExpansion::isAttributeMacroExpansionSourceLocation/2#3429148c` ON FIRST 1 OUTPUT Lhs.1, Rhs.1, Lhs.0
305226 ~0% {2} | JOIN WITH `Locatable::Locatable.getLocation/0#dispred#f3f7e2b2` ON FIRST 2 OUTPUT Lhs.0, Lhs.2
return r1
```
(No After; the predicate is no longer generated)
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Pull request overview
This PR optimizes a CodeQL query in the Rust library by fixing a performance issue caused by an inefficient join operation. The change introduces an intermediate variable to store the location before using it in a negative condition, significantly reducing tuple processing from ~5 billion to eliminating the problematic predicate entirely.
Changes:
- Introduced an intermediate variable
lto storen.getLocation()in theisFromMacroExpansionpredicate, preventing an expensive join operation
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paldepind
approved these changes
Jan 16, 2026
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Before
(No After; the predicate is no longer generated)