diff --git a/lib/Transforms/Utils/SSAUpdater.cpp b/lib/Transforms/Utils/SSAUpdater.cpp index d491cbb9155..25d50dbf2a8 100644 --- a/lib/Transforms/Utils/SSAUpdater.cpp +++ b/lib/Transforms/Utils/SSAUpdater.cpp @@ -529,9 +529,15 @@ void SSAUpdater::FindAvailableVals(BlockListTy *BlockList) { E = BlockList->rend(); I != E; ++I) { BBInfo *Info = *I; - // Check if this block contains a newly added PHI. - if (Info->DefBB != Info) + if (Info->DefBB != Info) { + // Record the available value at join nodes to speed up subsequent + // uses of this SSAUpdater for the same value. + if (Info->NumPreds > 1) + AvailableVals[Info->BB] = Info->DefBB->AvailableVal; continue; + } + + // Check if this block contains a newly added PHI. PHINode *PHI = dyn_cast(Info->AvailableVal); if (!PHI || PHI->getNumIncomingValues() == Info->NumPreds) continue;