-//===-- Transform/Utils/BasicBlockUtils.h - BasicBlock Utilities -*- C++ -*-==//
+//===-- 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.
// FIXME: Move to this file: BasicBlock::removePredecessor, BB::splitBasicBlock
#include "llvm/BasicBlock.h"
-class Instruction;
+#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.
BasicBlock::iterator &BI, Instruction *I);
// ReplaceInstWithInst - Replace the instruction specified by From with the
-// instruction specified by To. Note that this is slower than providing an
-// iterator directly, because the basic block containing From must be searched
-// for the instruction.
+// 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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