From f6236cc2e945bf101bd5082c43bb5837d6d4a26a Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 21 Apr 2008 02:57:57 +0000 Subject: [PATCH] Use the new SplitBlockPredecessors to implement a todo. llvm-svn: 50022 --- llvm/lib/Transforms/Scalar/JumpThreading.cpp | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index 358b8e284af2..3bca7ff19afd 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -17,6 +17,7 @@ #include "llvm/Pass.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/Statistic.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Local.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Compiler.h" @@ -194,10 +195,21 @@ bool JumpThreading::ThreadBlock(BasicBlock *BB) { SuccBB = SI->getSuccessor(SI->findCaseValue(PredCst)); } - // TODO: If there are multiple preds with the same incoming value for the PHI, - // factor them together so we get one thread block for the whole group. This - // is important for things like "phi i1 [true, true, false, true, x]" where - // we only need to clone the block for the true blocks once. + // If there are multiple preds with the same incoming value for the PHI, + // factor them together so we get one block to thread for the whole group. + // This is important for things like "phi i1 [true, true, false, true, x]" + // where we only need to clone the block for the true blocks once. + SmallVector CommonPreds; + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) + if (PN->getIncomingValue(i) == PredCst) + CommonPreds.push_back(PN->getIncomingBlock(i)); + if (CommonPreds.size() != 1) { + DOUT << " Factoring out " << CommonPreds.size() + << " common predecessors.\n"; + PredBB = SplitBlockPredecessors(BB, &CommonPreds[0], CommonPreds.size(), + ".thr_comm", this); + } + DOUT << " Threading edge from '" << PredBB->getNameStart() << "' to '" << SuccBB->getNameStart() << "' with cost: " << JumpThreadCost