//===-- Transform/Utils/BasicBlockUtils.h - BasicBlock Utils ----*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This family of functions perform manipulations on basic blocks, and // instructions contained within basic blocks. // //===----------------------------------------------------------------------===// #ifndef LLVM_TRANSFORMS_UTILS_BASICBLOCK_H #define LLVM_TRANSFORMS_UTILS_BASICBLOCK_H // FIXME: Move to this file: BasicBlock::removePredecessor, BB::splitBasicBlock #include "llvm/BasicBlock.h" #include "llvm/Support/CFG.h" namespace llvm { class Instruction; class Pass; class AliasAnalysis; /// DeleteDeadBlock - Delete the specified block, which must have no /// predecessors. void DeleteDeadBlock(BasicBlock *BB); /// FoldSingleEntryPHINodes - We know that BB has one predecessor. If there are /// any single-entry PHI nodes in it, fold them away. This handles the case /// when all entries to the PHI nodes in a block are guaranteed equal, such as /// when the block has exactly one predecessor. void FoldSingleEntryPHINodes(BasicBlock *BB); /// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, /// if possible. The return value indicates success or failure. bool MergeBlockIntoPredecessor(BasicBlock* BB, Pass* P = 0); // ReplaceInstWithValue - Replace all uses of an instruction (specified by BI) // with a value, then remove and delete the original instruction. // void ReplaceInstWithValue(BasicBlock::InstListType &BIL, BasicBlock::iterator &BI, Value *V); // ReplaceInstWithInst - Replace the instruction specified by BI with the // instruction specified by I. The original instruction is deleted and BI is // updated to point to the new instruction. // void ReplaceInstWithInst(BasicBlock::InstListType &BIL, BasicBlock::iterator &BI, Instruction *I); // ReplaceInstWithInst - Replace the instruction specified by From with the // instruction specified by To. // void ReplaceInstWithInst(Instruction *From, Instruction *To); /// CopyPrecedingStopPoint - If I is immediately preceded by a StopPoint, /// make a copy of the stoppoint before InsertPos (presumably before copying /// or moving I). void CopyPrecedingStopPoint(Instruction *I, BasicBlock::iterator InsertPos); /// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at the /// instruction before ScanFrom) checking to see if we have the value at the /// memory address *Ptr locally available within a small number of instructions. /// If the value is available, return it. /// /// If not, return the iterator for the last validated instruction that the /// value would be live through. If we scanned the entire block and didn't find /// something that invalidates *Ptr or provides it, ScanFrom would be left at /// begin() and this returns null. ScanFrom could also be left /// /// MaxInstsToScan specifies the maximum instructions to scan in the block. If /// it is set to 0, it will scan the whole block. You can also optionally /// specify an alias analysis implementation, which makes this more precise. Value *FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, BasicBlock::iterator &ScanFrom, unsigned MaxInstsToScan = 6, AliasAnalysis *AA = 0); /// FindFunctionBackedges - Analyze the specified function to find all of the /// loop backedges in the function and return them. This is a relatively cheap /// (compared to computing dominators and loop info) analysis. /// /// The output is added to Result, as pairs of <from,to> edge info. void FindFunctionBackedges(const Function &F, SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result); // RemoveSuccessor - Change the specified terminator instruction such that its // successor #SuccNum no longer exists. Because this reduces the outgoing // degree of the current basic block, the actual terminator instruction itself // may have to be changed. In the case where the last successor of the block is // deleted, a return instruction is inserted in its place which can cause a // suprising change in program behavior if it is not expected. // void RemoveSuccessor(TerminatorInst *TI, unsigned SuccNum); /// isCriticalEdge - Return true if the specified edge is a critical edge. /// Critical edges are edges from a block with multiple successors to a block /// with multiple predecessors. /// bool isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum, bool AllowIdenticalEdges = false); /// SplitCriticalEdge - If this edge is a critical edge, insert a new node to /// split the critical edge. This will update DominatorTree and /// DominatorFrontier information if it is available, thus calling this pass /// will not invalidate either of them. This returns true if the edge was split, /// false otherwise. /// /// If MergeIdenticalEdges is true (not the default), *all* edges from TI to the /// specified successor will be merged into the same critical edge block. /// This is most commonly interesting with switch instructions, which may /// have many edges to any one destination. This ensures that all edges to that /// dest go to one block instead of each going to a different block, but isn't /// the standard definition of a "critical edge". /// bool SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P = 0, bool MergeIdenticalEdges = false); inline bool SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, Pass *P = 0) { return SplitCriticalEdge(BB->getTerminator(), SI.getSuccessorIndex(), P); } /// SplitCriticalEdge - If the edge from *PI to BB is not critical, return /// false. Otherwise, split all edges between the two blocks and return true. /// This updates all of the same analyses as the other SplitCriticalEdge /// function. If P is specified, it updates the analyses /// described above. inline bool SplitCriticalEdge(BasicBlock *Succ, pred_iterator PI, Pass *P = 0) { bool MadeChange = false; TerminatorInst *TI = (*PI)->getTerminator(); for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) if (TI->getSuccessor(i) == Succ) MadeChange |= SplitCriticalEdge(TI, i, P); return MadeChange; } /// SplitCriticalEdge - If an edge from Src to Dst is critical, split the edge /// and return true, otherwise return false. This method requires that there be /// an edge between the two blocks. If P is specified, it updates the analyses /// described above. inline bool SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst, Pass *P = 0, bool MergeIdenticalEdges = false) { TerminatorInst *TI = Src->getTerminator(); unsigned i = 0; while (1) { assert(i != TI->getNumSuccessors() && "Edge doesn't exist!"); if (TI->getSuccessor(i) == Dst) return SplitCriticalEdge(TI, i, P, MergeIdenticalEdges); ++i; } } /// SplitEdge - Split the edge connecting specified block. Pass P must /// not be NULL. BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To, Pass *P); /// SplitBlock - Split the specified block at the specified instruction - every /// thing before SplitPt stays in Old and everything starting with SplitPt moves /// to a new block. The two blocks are joined by an unconditional branch and /// the loop info is updated. /// BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P); /// SplitBlockPredecessors - This method transforms BB by introducing a new /// basic block into the function, and moving some of the predecessors of BB to /// be predecessors of the new block. The new predecessors are indicated by the /// Preds array, which has NumPreds elements in it. The new block is given a /// suffix of 'Suffix'. This function returns the new block. /// /// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and /// DominanceFrontier, but no other analyses. BasicBlock *SplitBlockPredecessors(BasicBlock *BB, BasicBlock *const *Preds, unsigned NumPreds, const char *Suffix, Pass *P = 0); } // End llvm namespace #endif