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Diffstat (limited to 'gnu/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h')
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diff --git a/gnu/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h b/gnu/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h new file mode 100644 index 00000000000..13c856dfdc9 --- /dev/null +++ b/gnu/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h @@ -0,0 +1,297 @@ +//===-- 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_BASICBLOCKUTILS_H +#define LLVM_TRANSFORMS_UTILS_BASICBLOCKUTILS_H + +// FIXME: Move to this file: BasicBlock::removePredecessor, BB::splitBasicBlock + +#include "llvm/IR/BasicBlock.h" +#include "llvm/IR/CFG.h" + +namespace llvm { + +class MemoryDependenceAnalysis; +class DominatorTree; +class LoopInfo; +class Instruction; +class MDNode; +class ReturnInst; +class TargetLibraryInfo; +class TerminatorInst; + +/// 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, + MemoryDependenceAnalysis *MemDep = nullptr); + +/// DeleteDeadPHIs - Examine each PHI in the given block and delete it if it +/// is dead. Also recursively delete any operands that become dead as +/// a result. This includes tracing the def-use list from the PHI to see if +/// it is ultimately unused or if it reaches an unused cycle. Return true +/// if any PHIs were deleted. +bool DeleteDeadPHIs(BasicBlock *BB, const TargetLibraryInfo *TLI = nullptr); + +/// MergeBlockIntoPredecessor - Attempts to merge a block into its predecessor, +/// if possible. The return value indicates success or failure. +bool MergeBlockIntoPredecessor(BasicBlock *BB, DominatorTree *DT = nullptr, + LoopInfo *LI = nullptr, + MemoryDependenceAnalysis *MemDep = nullptr); + +// 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. Copies DebugLoc from BI to I, if I doesn't +// already have a DebugLoc. 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. Copies DebugLoc from BI to I, if I doesn't +// already have a DebugLoc. +// +void ReplaceInstWithInst(Instruction *From, Instruction *To); + +/// \brief Option class for critical edge splitting. +/// +/// This provides a builder interface for overriding the default options used +/// during critical edge splitting. +struct CriticalEdgeSplittingOptions { + DominatorTree *DT; + LoopInfo *LI; + bool MergeIdenticalEdges; + bool DontDeleteUselessPHIs; + bool PreserveLCSSA; + + CriticalEdgeSplittingOptions(DominatorTree *DT = nullptr, + LoopInfo *LI = nullptr) + : DT(DT), LI(LI), MergeIdenticalEdges(false), + DontDeleteUselessPHIs(false), PreserveLCSSA(false) {} + + CriticalEdgeSplittingOptions &setMergeIdenticalEdges() { + MergeIdenticalEdges = true; + return *this; + } + + CriticalEdgeSplittingOptions &setDontDeleteUselessPHIs() { + DontDeleteUselessPHIs = true; + return *this; + } + + CriticalEdgeSplittingOptions &setPreserveLCSSA() { + PreserveLCSSA = true; + return *this; + } +}; + +/// SplitCriticalEdge - If this edge is a critical edge, insert a new node to +/// split the critical edge. This will update the analyses passed in through +/// the option struct. This returns the new block if the edge was split, null +/// otherwise. +/// +/// If MergeIdenticalEdges in the options struct 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". +/// +/// It is invalid to call this function on a critical edge that starts at an +/// IndirectBrInst. Splitting these edges will almost always create an invalid +/// program because the address of the new block won't be the one that is jumped +/// to. +/// +BasicBlock *SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, + const CriticalEdgeSplittingOptions &Options = + CriticalEdgeSplittingOptions()); + +inline BasicBlock * +SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, + const CriticalEdgeSplittingOptions &Options = + CriticalEdgeSplittingOptions()) { + return SplitCriticalEdge(BB->getTerminator(), SI.getSuccessorIndex(), + Options); +} + +/// 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, + const CriticalEdgeSplittingOptions &Options = + CriticalEdgeSplittingOptions()) { + 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, Options); + 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. It updates the analyses +/// passed in the options struct +inline BasicBlock * +SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst, + const CriticalEdgeSplittingOptions &Options = + CriticalEdgeSplittingOptions()) { + 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, Options); + ++i; + } +} + +// SplitAllCriticalEdges - Loop over all of the edges in the CFG, +// breaking critical edges as they are found. +// Returns the number of broken edges. +unsigned SplitAllCriticalEdges(Function &F, + const CriticalEdgeSplittingOptions &Options = + CriticalEdgeSplittingOptions()); + +/// SplitEdge - Split the edge connecting specified block. +BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To, + DominatorTree *DT = nullptr, LoopInfo *LI = nullptr); + +/// 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, + DominatorTree *DT = nullptr, LoopInfo *LI = nullptr); + +/// SplitBlockPredecessors - This method introduces at least one new basic block +/// into the function and moves some of the predecessors of BB to be +/// predecessors of the new block. The new predecessors are indicated by the +/// Preds array. The new block is given a suffix of 'Suffix'. Returns new basic +/// block to which predecessors from Preds are now pointing. +/// +/// If BB is a landingpad block then additional basicblock might be introduced. +/// It will have Suffix+".split_lp". See SplitLandingPadPredecessors for more +/// details on this case. +/// +/// This currently updates the LLVM IR, DominatorTree, LoopInfo, and LCCSA but +/// no other analyses. In particular, it does not preserve LoopSimplify +/// (because it's complicated to handle the case where one of the edges being +/// split is an exit of a loop with other exits). +/// +BasicBlock *SplitBlockPredecessors(BasicBlock *BB, ArrayRef<BasicBlock *> Preds, + const char *Suffix, + DominatorTree *DT = nullptr, + LoopInfo *LI = nullptr, + bool PreserveLCSSA = false); + +/// SplitLandingPadPredecessors - This method transforms the landing pad, +/// OrigBB, by introducing two new basic blocks into the function. One of those +/// new basic blocks gets the predecessors listed in Preds. The other basic +/// block gets the remaining predecessors of OrigBB. The landingpad instruction +/// OrigBB is clone into both of the new basic blocks. The new blocks are given +/// the suffixes 'Suffix1' and 'Suffix2', and are returned in the NewBBs vector. +/// +/// This currently updates the LLVM IR, DominatorTree, LoopInfo, and LCCSA but +/// no other analyses. In particular, it does not preserve LoopSimplify +/// (because it's complicated to handle the case where one of the edges being +/// split is an exit of a loop with other exits). +/// +void SplitLandingPadPredecessors(BasicBlock *OrigBB, + ArrayRef<BasicBlock *> Preds, + const char *Suffix, const char *Suffix2, + SmallVectorImpl<BasicBlock *> &NewBBs, + DominatorTree *DT = nullptr, + LoopInfo *LI = nullptr, + bool PreserveLCSSA = false); + +/// FoldReturnIntoUncondBranch - This method duplicates the specified return +/// instruction into a predecessor which ends in an unconditional branch. If +/// the return instruction returns a value defined by a PHI, propagate the +/// right value into the return. It returns the new return instruction in the +/// predecessor. +ReturnInst *FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB, + BasicBlock *Pred); + +/// SplitBlockAndInsertIfThen - Split the containing block at the +/// specified instruction - everything before and including SplitBefore stays +/// in the old basic block, and everything after SplitBefore is moved to a +/// new block. The two blocks are connected by a conditional branch +/// (with value of Cmp being the condition). +/// Before: +/// Head +/// SplitBefore +/// Tail +/// After: +/// Head +/// if (Cond) +/// ThenBlock +/// SplitBefore +/// Tail +/// +/// If Unreachable is true, then ThenBlock ends with +/// UnreachableInst, otherwise it branches to Tail. +/// Returns the NewBasicBlock's terminator. +/// +/// Updates DT if given. +TerminatorInst *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore, + bool Unreachable, + MDNode *BranchWeights = nullptr, + DominatorTree *DT = nullptr); + +/// SplitBlockAndInsertIfThenElse is similar to SplitBlockAndInsertIfThen, +/// but also creates the ElseBlock. +/// Before: +/// Head +/// SplitBefore +/// Tail +/// After: +/// Head +/// if (Cond) +/// ThenBlock +/// else +/// ElseBlock +/// SplitBefore +/// Tail +void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore, + TerminatorInst **ThenTerm, + TerminatorInst **ElseTerm, + MDNode *BranchWeights = nullptr); + +/// +/// GetIfCondition - Check whether BB is the merge point of a if-region. +/// If so, return the boolean condition that determines which entry into +/// BB will be taken. Also, return by references the block that will be +/// entered from if the condition is true, and the block that will be +/// entered if the condition is false. +Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue, + BasicBlock *&IfFalse); +} // End llvm namespace + +#endif |