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//===-- 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;
// 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);
// 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 (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);
} // End llvm namespace
#endif
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