//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_TRANSFORMS_UTILS_BASICBLOCK_H
-#define LLVM_TRANSFORMS_UTILS_BASICBLOCK_H
+#ifndef LLVM_TRANSFORMS_UTILS_BASICBLOCKUTILS_H
+#define LLVM_TRANSFORMS_UTILS_BASICBLOCKUTILS_H
// FIXME: Move to this file: BasicBlock::removePredecessor, BB::splitBasicBlock
-#include "llvm/BasicBlock.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
namespace llvm {
-class Instruction;
-class Pass;
class AliasAnalysis;
+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);
+void FoldSingleEntryPHINodes(BasicBlock *BB, AliasAnalysis *AA = nullptr,
+ 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.
-void DeleteDeadPHIs(BasicBlock *BB);
+/// 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, Pass* P = 0);
+bool MergeBlockIntoPredecessor(BasicBlock *BB, DominatorTree *DT = nullptr,
+ LoopInfo *LI = nullptr,
+ AliasAnalysis *AA = 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 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.
+/// \brief Option class for critical edge splitting.
///
-/// 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);
+/// This provides a builder interface for overriding the default options used
+/// during critical edge splitting.
+struct CriticalEdgeSplittingOptions {
+ AliasAnalysis *AA;
+ DominatorTree *DT;
+ LoopInfo *LI;
+ bool MergeIdenticalEdges;
+ bool DontDeleteUselessPHIs;
+ bool PreserveLCSSA;
-/// 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);
+ CriticalEdgeSplittingOptions()
+ : AA(nullptr), DT(nullptr), LI(nullptr), MergeIdenticalEdges(false),
+ DontDeleteUselessPHIs(false), PreserveLCSSA(false) {}
+
+ /// \brief Basic case of setting up all the analysis.
+ CriticalEdgeSplittingOptions(AliasAnalysis *AA, DominatorTree *DT = nullptr,
+ LoopInfo *LI = nullptr)
+ : AA(AA), DT(DT), LI(LI), MergeIdenticalEdges(false),
+ DontDeleteUselessPHIs(false), PreserveLCSSA(false) {}
+
+ /// \brief A common pattern is to preserve the dominator tree and loop
+ /// info but not care about AA.
+ CriticalEdgeSplittingOptions(DominatorTree *DT, LoopInfo *LI)
+ : AA(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 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.
+/// 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 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".
+/// 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,
- Pass *P = 0, bool MergeIdenticalEdges = false);
+ const CriticalEdgeSplittingOptions &Options =
+ CriticalEdgeSplittingOptions());
-inline BasicBlock *SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, Pass *P = 0) {
- return SplitCriticalEdge(BB->getTerminator(), SI.getSuccessorIndex(), P);
+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
/// 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) {
+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, P);
+ 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. If P is specified, it updates the analyses
-/// described above.
-inline BasicBlock *SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst,
- Pass *P = 0,
- bool MergeIdenticalEdges = false) {
+/// 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, P, MergeIdenticalEdges);
+ return SplitCriticalEdge(TI, i, Options);
++i;
}
}
-/// SplitEdge - Split the edge connecting specified block. Pass P must
-/// not be NULL.
-BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To, Pass *P);
+// 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, 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.
+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, AliasAnalysis, DominatorTree,
/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses.
/// 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, BasicBlock *const *Preds,
- unsigned NumPreds, const char *Suffix,
- Pass *P = 0);
-
+BasicBlock *SplitBlockPredecessors(BasicBlock *BB, ArrayRef<BasicBlock *> Preds,
+ const char *Suffix,
+ AliasAnalysis *AA = nullptr,
+ 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, AliasAnalysis, DominatorTree,
+/// DominanceFrontier, 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,
+ AliasAnalysis *AA = nullptr,
+ 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
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