llvm/llvm-project

[ConstantFolding] Move `LibCallSimplifier::optimizeFdim` into ConstantFolding

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#171877 opened on Dec 11, 2025

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code-cleanupconstant-foldingfloating-pointgood first issue

Description

In https://github.com/llvm/llvm-project/pull/109235 the constant folding logic was implemented in SimplifyLibCalls.cpp. But it should be put in ConstantFoldLibCall2 since both operands are known constants.

Contributor guide

Tech stack
cpp
Domain
tooling
Issue type
refactor
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
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++ experienceLLVM codebase navigation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Review the implementation in SimplifyLibCalls.cpp from PR #109235 (linked in issue). Study the ConstantFoldLibCall2 interface in the LLVM codebase. Then, move the optimizeFdim function to the appropriate location, ensuring the constant folding logic is applied correctly.