| //===-- 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); |
| |
| /// 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); |
| |
| |
| |
| // 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 |