diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolutionExpander.cpp | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp index 20d6e20..b6af26a 100644 --- a/lib/Analysis/ScalarEvolutionExpander.cpp +++ b/lib/Analysis/ScalarEvolutionExpander.cpp @@ -215,13 +215,11 @@ static bool FactorOutConstant(const SCEV *&S, /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP /// instead of using ptrtoint+arithmetic+inttoptr. This helps -/// BasicAliasAnalysis analyze the result. However, it suffers from the -/// underlying bug described in PR2831. Addition in LLVM currently always -/// has two's complement wrapping guaranteed. However, the semantics for -/// getelementptr overflow are ambiguous. In the common case though, this -/// expansion gets used when a GEP in the original code has been converted -/// into integer arithmetic, in which case the resulting code will be no -/// more undefined than it was originally. +/// BasicAliasAnalysis analyze the result. +/// +/// Design note: This depends on ScalarEvolution not recognizing inttoptr +/// and ptrtoint operators, as they may introduce pointer arithmetic +/// which may not be safely converted into getelementptr. /// /// Design note: It might seem desirable for this function to be more /// loop-aware. If some of the indices are loop-invariant while others |