Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 339 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/Transforms/Utils/BasicBlockUtils.h b/clang-r353983/include/llvm/Transforms/Utils/BasicBlockUtils.h
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+//===- Transform/Utils/BasicBlockUtils.h - BasicBlock Utils -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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/ADT/ArrayRef.h"
+#include "llvm/Analysis/DomTreeUpdater.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/InstrTypes.h"
+#include <cassert>
+
+namespace llvm {
+
+class BlockFrequencyInfo;
+class BranchProbabilityInfo;
+class DominatorTree;
+class DomTreeUpdater;
+class Function;
+class Instruction;
+class LoopInfo;
+class MDNode;
+class MemoryDependenceResults;
+class MemorySSAUpdater;
+class ReturnInst;
+class TargetLibraryInfo;
+class Value;
+
+/// Replace contents of every block in \p BBs with single unreachable
+/// instruction. If \p Updates is specified, collect all necessary DT updates
+/// into this vector. If \p KeepOneInputPHIs is true, one-input Phis in
+/// successors of blocks being deleted will be preserved.
+void DetatchDeadBlocks(ArrayRef <BasicBlock *> BBs,
+                       SmallVectorImpl<DominatorTree::UpdateType> *Updates,
+                       bool KeepOneInputPHIs = false);
+
+/// Delete the specified block, which must have no predecessors.
+void DeleteDeadBlock(BasicBlock *BB, DomTreeUpdater *DTU = nullptr,
+                     bool KeepOneInputPHIs = false);
+
+/// Delete the specified blocks from \p BB. The set of deleted blocks must have
+/// no predecessors that are not being deleted themselves. \p BBs must have no
+/// duplicating blocks. If there are loops among this set of blocks, all
+/// relevant loop info updates should be done before this function is called.
+/// If \p KeepOneInputPHIs is true, one-input Phis in successors of blocks
+/// being deleted will be preserved.
+void DeleteDeadBlocks(ArrayRef <BasicBlock *> BBs,
+                      DomTreeUpdater *DTU = nullptr,
+                      bool KeepOneInputPHIs = false);
+
+/// 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,
+                             MemoryDependenceResults *MemDep = nullptr);
+
+/// 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);
+
+/// Attempts to merge a block into its predecessor, if possible. The return
+/// value indicates success or failure.
+bool MergeBlockIntoPredecessor(BasicBlock *BB, DomTreeUpdater *DTU = nullptr,
+                               LoopInfo *LI = nullptr,
+                               MemorySSAUpdater *MSSAU = nullptr,
+                               MemoryDependenceResults *MemDep = nullptr);
+
+/// 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);
+
+/// 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);
+
+/// 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);
+
+/// 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;
+  MemorySSAUpdater *MSSAU;
+  bool MergeIdenticalEdges = false;
+  bool KeepOneInputPHIs = false;
+  bool PreserveLCSSA = false;
+
+  CriticalEdgeSplittingOptions(DominatorTree *DT = nullptr,
+                               LoopInfo *LI = nullptr,
+                               MemorySSAUpdater *MSSAU = nullptr)
+      : DT(DT), LI(LI), MSSAU(MSSAU) {}
+
+  CriticalEdgeSplittingOptions &setMergeIdenticalEdges() {
+    MergeIdenticalEdges = true;
+    return *this;
+  }
+
+  CriticalEdgeSplittingOptions &setKeepOneInputPHIs() {
+    KeepOneInputPHIs = true;
+    return *this;
+  }
+
+  CriticalEdgeSplittingOptions &setPreserveLCSSA() {
+    PreserveLCSSA = true;
+    return *this;
+  }
+};
+
+/// 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(Instruction *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);
+}
+
+/// 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;
+  Instruction *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;
+}
+
+/// 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()) {
+  Instruction *TI = Src->getTerminator();
+  unsigned i = 0;
+  while (true) {
+    assert(i != TI->getNumSuccessors() && "Edge doesn't exist!");
+    if (TI->getSuccessor(i) == Dst)
+      return SplitCriticalEdge(TI, i, Options);
+    ++i;
+  }
+}
+
+/// 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());
+
+/// Split the edge connecting specified block.
+BasicBlock *SplitEdge(BasicBlock *From, BasicBlock *To,
+                      DominatorTree *DT = nullptr, LoopInfo *LI = nullptr,
+                      MemorySSAUpdater *MSSAU = nullptr);
+
+/// Split the specified block at the specified instruction - everything 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,
+                       MemorySSAUpdater *MSSAU = nullptr);
+
+/// 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,
+                                   MemorySSAUpdater *MSSAU = nullptr,
+                                   bool PreserveLCSSA = false);
+
+/// 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,
+    MemorySSAUpdater *MSSAU = nullptr, bool PreserveLCSSA = false);
+
+/// 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,
+                                       DomTreeUpdater *DTU = nullptr);
+
+/// Split the containing block at the specified instruction - everything before
+/// SplitBefore stays in the old basic block, and the rest of the instructions
+/// in the BB are 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 and LI if given.
+Instruction *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
+                                       bool Unreachable,
+                                       MDNode *BranchWeights = nullptr,
+                                       DominatorTree *DT = nullptr,
+                                       LoopInfo *LI = 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,
+                                   Instruction **ThenTerm,
+                                   Instruction **ElseTerm,
+                                   MDNode *BranchWeights = nullptr);
+
+/// 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.
+///
+/// This does no checking to see if the true/false blocks have large or unsavory
+/// instructions in them.
+Value *GetIfCondition(BasicBlock *BB, BasicBlock *&IfTrue,
+                      BasicBlock *&IfFalse);
+
+// Split critical edges where the source of the edge is an indirectbr
+// instruction. This isn't always possible, but we can handle some easy cases.
+// This is useful because MI is unable to split such critical edges,
+// which means it will not be able to sink instructions along those edges.
+// This is especially painful for indirect branches with many successors, where
+// we end up having to prepare all outgoing values in the origin block.
+//
+// Our normal algorithm for splitting critical edges requires us to update
+// the outgoing edges of the edge origin block, but for an indirectbr this
+// is hard, since it would require finding and updating the block addresses
+// the indirect branch uses. But if a block only has a single indirectbr
+// predecessor, with the others being regular branches, we can do it in a
+// different way.
+// Say we have A -> D, B -> D, I -> D where only I -> D is an indirectbr.
+// We can split D into D0 and D1, where D0 contains only the PHIs from D,
+// and D1 is the D block body. We can then duplicate D0 as D0A and D0B, and
+// create the following structure:
+// A -> D0A, B -> D0A, I -> D0B, D0A -> D1, D0B -> D1
+// If BPI and BFI aren't non-null, BPI/BFI will be updated accordingly.
+bool SplitIndirectBrCriticalEdges(Function &F,
+                                  BranchProbabilityInfo *BPI = nullptr,
+                                  BlockFrequencyInfo *BFI = nullptr);
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_BASICBLOCKUTILS_H