diff options
Diffstat (limited to 'lib/Transforms/Scalar/CodeGenPrepare.cpp')
-rw-r--r-- | lib/Transforms/Scalar/CodeGenPrepare.cpp | 167 |
1 files changed, 75 insertions, 92 deletions
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp index fa60d3f..7ceda1f 100644 --- a/lib/Transforms/Scalar/CodeGenPrepare.cpp +++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp @@ -32,7 +32,6 @@ #include "llvm/ADT/SmallSet.h" #include "llvm/Assembly/Writer.h" #include "llvm/Support/CallSite.h" -#include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/GetElementPtrTypeIterator.h" #include "llvm/Support/PatternMatch.h" @@ -40,9 +39,6 @@ using namespace llvm; using namespace llvm::PatternMatch; -static cl::opt<bool> FactorCommonPreds("split-critical-paths-tweak", - cl::init(false), cl::Hidden); - namespace { class CodeGenPrepare : public FunctionPass { /// TLI - Keep a pointer of a TargetLowering to consult for determining @@ -301,6 +297,70 @@ void CodeGenPrepare::EliminateMostlyEmptyBlock(BasicBlock *BB) { DEBUG(dbgs() << "AFTER:\n" << *DestBB << "\n\n\n"); } +/// FindReusablePredBB - Check all of the predecessors of the block DestPHI +/// lives in to see if there is a block that we can reuse as a critical edge +/// from TIBB. +static BasicBlock *FindReusablePredBB(PHINode *DestPHI, BasicBlock *TIBB) { + BasicBlock *Dest = DestPHI->getParent(); + + /// TIPHIValues - This array is lazily computed to determine the values of + /// PHIs in Dest that TI would provide. + SmallVector<Value*, 32> TIPHIValues; + + /// TIBBEntryNo - This is a cache to speed up pred queries for TIBB. + unsigned TIBBEntryNo = 0; + + // Check to see if Dest has any blocks that can be used as a split edge for + // this terminator. + for (unsigned pi = 0, e = DestPHI->getNumIncomingValues(); pi != e; ++pi) { + BasicBlock *Pred = DestPHI->getIncomingBlock(pi); + // To be usable, the pred has to end with an uncond branch to the dest. + BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator()); + if (!PredBr || !PredBr->isUnconditional()) + continue; + // Must be empty other than the branch and debug info. + BasicBlock::iterator I = Pred->begin(); + while (isa<DbgInfoIntrinsic>(I)) + I++; + if (&*I != PredBr) + continue; + // Cannot be the entry block; its label does not get emitted. + if (Pred == &Dest->getParent()->getEntryBlock()) + continue; + + // Finally, since we know that Dest has phi nodes in it, we have to make + // sure that jumping to Pred will have the same effect as going to Dest in + // terms of PHI values. + PHINode *PN; + unsigned PHINo = 0; + unsigned PredEntryNo = pi; + + bool FoundMatch = true; + for (BasicBlock::iterator I = Dest->begin(); + (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) { + if (PHINo == TIPHIValues.size()) { + if (PN->getIncomingBlock(TIBBEntryNo) != TIBB) + TIBBEntryNo = PN->getBasicBlockIndex(TIBB); + TIPHIValues.push_back(PN->getIncomingValue(TIBBEntryNo)); + } + + // If the PHI entry doesn't work, we can't use this pred. + if (PN->getIncomingBlock(PredEntryNo) != Pred) + PredEntryNo = PN->getBasicBlockIndex(Pred); + + if (TIPHIValues[PHINo] != PN->getIncomingValue(PredEntryNo)) { + FoundMatch = false; + break; + } + } + + // If we found a workable predecessor, change TI to branch to Succ. + if (FoundMatch) + return Pred; + } + return 0; +} + /// SplitEdgeNicely - Split the critical edge from TI to its specified /// successor if it will improve codegen. We only do this if the successor has @@ -315,13 +375,12 @@ static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum, BasicBlock *Dest = TI->getSuccessor(SuccNum); assert(isa<PHINode>(Dest->begin()) && "This should only be called if Dest has a PHI!"); + PHINode *DestPHI = cast<PHINode>(Dest->begin()); // Do not split edges to EH landing pads. - if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI)) { + if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI)) if (Invoke->getSuccessor(1) == Dest) return; - } - // As a hack, never split backedges of loops. Even though the copy for any // PHIs inserted on the backedge would be dead for exits from the loop, we @@ -329,92 +388,16 @@ static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum, if (BackEdges.count(std::make_pair(TIBB, Dest))) return; - if (!FactorCommonPreds) { - /// TIPHIValues - This array is lazily computed to determine the values of - /// PHIs in Dest that TI would provide. - SmallVector<Value*, 32> TIPHIValues; - - // Check to see if Dest has any blocks that can be used as a split edge for - // this terminator. - for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) { - BasicBlock *Pred = *PI; - // To be usable, the pred has to end with an uncond branch to the dest. - BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator()); - if (!PredBr || !PredBr->isUnconditional()) - continue; - // Must be empty other than the branch and debug info. - BasicBlock::iterator I = Pred->begin(); - while (isa<DbgInfoIntrinsic>(I)) - I++; - if (dyn_cast<Instruction>(I) != PredBr) - continue; - // Cannot be the entry block; its label does not get emitted. - if (Pred == &(Dest->getParent()->getEntryBlock())) - continue; - - // Finally, since we know that Dest has phi nodes in it, we have to make - // sure that jumping to Pred will have the same effect as going to Dest in - // terms of PHI values. - PHINode *PN; - unsigned PHINo = 0; - bool FoundMatch = true; - for (BasicBlock::iterator I = Dest->begin(); - (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) { - if (PHINo == TIPHIValues.size()) - TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB)); - - // If the PHI entry doesn't work, we can't use this pred. - if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) { - FoundMatch = false; - break; - } - } - - // If we found a workable predecessor, change TI to branch to Succ. - if (FoundMatch) { - ProfileInfo *PFI = P->getAnalysisIfAvailable<ProfileInfo>(); - if (PFI) - PFI->splitEdge(TIBB, Dest, Pred); - Dest->removePredecessor(TIBB); - TI->setSuccessor(SuccNum, Pred); - return; - } - } - - SplitCriticalEdge(TI, SuccNum, P, true); + if (BasicBlock *ReuseBB = FindReusablePredBB(DestPHI, TIBB)) { + ProfileInfo *PFI = P->getAnalysisIfAvailable<ProfileInfo>(); + if (PFI) + PFI->splitEdge(TIBB, Dest, ReuseBB); + Dest->removePredecessor(TIBB); + TI->setSuccessor(SuccNum, ReuseBB); return; } - PHINode *PN; - SmallVector<Value*, 8> TIPHIValues; - for (BasicBlock::iterator I = Dest->begin(); - (PN = dyn_cast<PHINode>(I)); ++I) - TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB)); - - SmallVector<BasicBlock*, 8> IdenticalPreds; - for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) { - BasicBlock *Pred = *PI; - if (BackEdges.count(std::make_pair(Pred, Dest))) - continue; - if (PI == TIBB) - IdenticalPreds.push_back(Pred); - else { - bool Identical = true; - unsigned PHINo = 0; - for (BasicBlock::iterator I = Dest->begin(); - (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) - if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) { - Identical = false; - break; - } - if (Identical) - IdenticalPreds.push_back(Pred); - } - } - - assert(!IdenticalPreds.empty()); - SplitBlockPredecessors(Dest, &IdenticalPreds[0], IdenticalPreds.size(), - ".critedge", P); + SplitCriticalEdge(TI, SuccNum, P, true); } @@ -629,7 +612,7 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr, // we'd end up sinking both muls. if (AddrMode.BaseReg) { Value *V = AddrMode.BaseReg; - if (isa<PointerType>(V->getType())) + if (V->getType()->isPointerTy()) V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt); if (V->getType() != IntPtrTy) V = CastInst::CreateIntegerCast(V, IntPtrTy, /*isSigned=*/true, @@ -642,7 +625,7 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr, Value *V = AddrMode.ScaledReg; if (V->getType() == IntPtrTy) { // done. - } else if (isa<PointerType>(V->getType())) { + } else if (V->getType()->isPointerTy()) { V = new PtrToIntInst(V, IntPtrTy, "sunkaddr", InsertPt); } else if (cast<IntegerType>(IntPtrTy)->getBitWidth() < cast<IntegerType>(V->getType())->getBitWidth()) { |