llvm/llvm-project

llvm/lib/CodeGen/LiveRangeUtils.h:40: Iterators applied to wrong data structure ?

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#122,937 opened on Jan 14, 2025

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code-qualitygood first issuellvm:codegen

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Description

Static analyser cppcheck says:

llvm/lib/CodeGen/LiveRangeUtils.h:40:6: error: Same iterator is used with different containers 'LR' and 'LR.segments'. [iterators1]

Source code is

typename LiveRangeT::iterator J = LR.begin(), E = LR.end(); // ... LR.segments.erase(J, E);

So J and E are iterators for LR, but get used on LR.segments.

I am surprised this compiles.

Contributor guide

Research direction
Verify if the iterators from LR are valid for LR.segments, and if not, determine the correct way to erase segments. Check if the fix requires changing the erase call to use LR.segments' own iterators or if the loop variable should be iterating over segments.
Tech stack
cpp
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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Clear
Prerequisites
C++
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55