diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/SimplifyCFG.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index f02f80cc1b7..e7358dbcb62 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -1654,14 +1654,11 @@ namespace { } // end anonymous namespace -/// Given an unconditional branch that goes to BBEnd, -/// check whether BBEnd has only two predecessors and the other predecessor -/// ends with an unconditional branch. If it is true, sink any common code -/// in the two predecessors to BBEnd. -static bool SinkThenElseCodeToEnd(BranchInst *BI1) { - assert(BI1->isUnconditional()); - BasicBlock *BBEnd = BI1->getSuccessor(0); - +/// Check whether BB's predecessors end with unconditional branches. If it is +/// true, sink any common code from the predecessors to BB. +/// We also allow one predecessor to end with conditional branch (but no more +/// than one). +static bool SinkCommonCodeFromPredecessors(BasicBlock *BB) { // We support two situations: // (1) all incoming arcs are unconditional // (2) one incoming arc is conditional @@ -1705,7 +1702,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) { // SmallVector<BasicBlock*,4> UnconditionalPreds; Instruction *Cond = nullptr; - for (auto *B : predecessors(BBEnd)) { + for (auto *B : predecessors(BB)) { auto *T = B->getTerminator(); if (isa<BranchInst>(T) && cast<BranchInst>(T)->isUnconditional()) UnconditionalPreds.push_back(B); @@ -1773,8 +1770,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) { DEBUG(dbgs() << "SINK: Splitting edge\n"); // We have a conditional edge and we're going to sink some instructions. // Insert a new block postdominating all blocks we're going to sink from. - if (!SplitBlockPredecessors(BI1->getSuccessor(0), UnconditionalPreds, - ".sink.split")) + if (!SplitBlockPredecessors(BB, UnconditionalPreds, ".sink.split")) // Edges couldn't be split. return false; Changed = true; @@ -5728,9 +5724,6 @@ bool SimplifyCFGOpt::SimplifyUncondBranch(BranchInst *BI, BasicBlock *BB = BI->getParent(); BasicBlock *Succ = BI->getSuccessor(0); - if (SinkCommon && Options.SinkCommonInsts && SinkThenElseCodeToEnd(BI)) - return true; - // If the Terminator is the only non-phi instruction, simplify the block. // If LoopHeader is provided, check if the block or its successor is a loop // header. (This is for early invocations before loop simplify and @@ -6008,6 +6001,9 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) { if (MergeBlockIntoPredecessor(BB)) return true; + if (SinkCommon && Options.SinkCommonInsts) + Changed |= SinkCommonCodeFromPredecessors(BB); + IRBuilder<> Builder(BB); // If there is a trivial two-entry PHI node in this basic block, and we can |
