llvm-project

a0f704dc - [SCEV] Skip invalidation with empty ValueExprMap (NFC). (#226845)

[SCEV] Skip invalidation with empty ValueExprMap (NFC). (#226845) forgetLoop, forgetValue and forgetValues walk the def-use chains from the forgotten instructions and erase each visited value's SCEV. This can be expensive. If ValueExprMap is empty, there's nothing to forget and skipping the walk reduces compile-time a bit: stage1-O3: -0.05% stage1-ReleaseThinLTO: -0.05% stage1-ReleaseLTO-g: -0.03% stage1-aarch64-O3: -0.04% stage2-O3: -0.05% stage2-clang: -0.01% https://llvm-compile-time-tracker.com/compare.php?from=899d817c7950c997402cd229935cd822acf45b08&to=c43f92b9840b62f75ab8a45b7379188d78d81135&stat=instructions:u PR: https://github.com/llvm/llvm-project/pull/226845