Update prebuilt Clang to match Android kernel.

Bug: 132428451
Change-Id: I8f6e2cb23f381fc0c02ddea99b867e58e925e5be
diff --git a/linux-x64/clang/include/llvm/Analysis/MustExecute.h b/linux-x64/clang/include/llvm/Analysis/MustExecute.h
index 40a0273..3ef539c 100644
--- a/linux-x64/clang/include/llvm/Analysis/MustExecute.h
+++ b/linux-x64/clang/include/llvm/Analysis/MustExecute.h
@@ -1,9 +1,8 @@
 //===- MustExecute.h - Is an instruction known to execute--------*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// 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
 //
 //===----------------------------------------------------------------------===//
 /// \file
@@ -19,6 +18,7 @@
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/Analysis/EHPersonalities.h"
+#include "llvm/Analysis/InstructionPrecedenceTracking.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Dominators.h"
@@ -45,33 +45,30 @@
 /// loop were made and the info wasn't recomputed properly, the behavior of all
 /// methods except for computeLoopSafetyInfo is undefined.
 class LoopSafetyInfo {
-  bool MayThrow = false;       // The current loop contains an instruction which
-                               // may throw.
-  bool HeaderMayThrow = false; // Same as previous, but specific to loop header
-
-  /// Collect all blocks from \p CurLoop which lie on all possible paths from
-  /// the header of \p CurLoop (inclusive) to BB (exclusive) into the set
-  /// \p Predecessors. If \p BB is the header, \p Predecessors will be empty.
-  void collectTransitivePredecessors(
-      const Loop *CurLoop, const BasicBlock *BB,
-      SmallPtrSetImpl<const BasicBlock *> &Predecessors) const;
-
-public:
   // Used to update funclet bundle operands.
   DenseMap<BasicBlock *, ColorVector> BlockColors;
 
-  /// Returns true iff the header block of the loop for which this info is
-  /// calculated contains an instruction that may throw or otherwise exit
-  /// abnormally.
-  bool headerMayThrow() const;
+protected:
+  /// Computes block colors.
+  void computeBlockColors(const Loop *CurLoop);
+
+public:
+  /// Returns block colors map that is used to update funclet operand bundles.
+  const DenseMap<BasicBlock *, ColorVector> &getBlockColors() const;
+
+  /// Copy colors of block \p Old into the block \p New.
+  void copyColors(BasicBlock *New, BasicBlock *Old);
+
+  /// Returns true iff the block \p BB potentially may throw exception. It can
+  /// be false-positive in cases when we want to avoid complex analysis.
+  virtual bool blockMayThrow(const BasicBlock *BB) const = 0;
 
   /// Returns true iff any block of the loop for which this info is contains an
   /// instruction that may throw or otherwise exit abnormally.
-  bool anyBlockMayThrow() const;
+  virtual bool anyBlockMayThrow() const = 0;
 
   /// Return true if we must reach the block \p BB under assumption that the
-  /// loop \p CurLoop is entered and no instruction throws or otherwise exits
-  /// abnormally.
+  /// loop \p CurLoop is entered.
   bool allLoopPathsLeadToBlock(const Loop *CurLoop, const BasicBlock *BB,
                                const DominatorTree *DT) const;
 
@@ -80,16 +77,92 @@
   /// as argument. Updates safety information in LoopSafetyInfo argument.
   /// Note: This is defined to clear and reinitialize an already initialized
   /// LoopSafetyInfo.  Some callers rely on this fact.
-  void computeLoopSafetyInfo(Loop *);
+  virtual void computeLoopSafetyInfo(const Loop *CurLoop) = 0;
+
+  /// Returns true if the instruction in a loop is guaranteed to execute at
+  /// least once (under the assumption that the loop is entered).
+  virtual bool isGuaranteedToExecute(const Instruction &Inst,
+                                     const DominatorTree *DT,
+                                     const Loop *CurLoop) const = 0;
 
   LoopSafetyInfo() = default;
+
+  virtual ~LoopSafetyInfo() = default;
 };
 
-/// Returns true if the instruction in a loop is guaranteed to execute at least
-/// once (under the assumption that the loop is entered).
-bool isGuaranteedToExecute(const Instruction &Inst, const DominatorTree *DT,
-                           const Loop *CurLoop,
-                           const LoopSafetyInfo *SafetyInfo);
+
+/// Simple and conservative implementation of LoopSafetyInfo that can give
+/// false-positive answers to its queries in order to avoid complicated
+/// analysis.
+class SimpleLoopSafetyInfo: public LoopSafetyInfo {
+  bool MayThrow = false;       // The current loop contains an instruction which
+                               // may throw.
+  bool HeaderMayThrow = false; // Same as previous, but specific to loop header
+
+public:
+  virtual bool blockMayThrow(const BasicBlock *BB) const;
+
+  virtual bool anyBlockMayThrow() const;
+
+  virtual void computeLoopSafetyInfo(const Loop *CurLoop);
+
+  virtual bool isGuaranteedToExecute(const Instruction &Inst,
+                                     const DominatorTree *DT,
+                                     const Loop *CurLoop) const;
+
+  SimpleLoopSafetyInfo() : LoopSafetyInfo() {};
+
+  virtual ~SimpleLoopSafetyInfo() {};
+};
+
+/// This implementation of LoopSafetyInfo use ImplicitControlFlowTracking to
+/// give precise answers on "may throw" queries. This implementation uses cache
+/// that should be invalidated by calling the methods insertInstructionTo and
+/// removeInstruction whenever we modify a basic block's contents by adding or
+/// removing instructions.
+class ICFLoopSafetyInfo: public LoopSafetyInfo {
+  bool MayThrow = false;       // The current loop contains an instruction which
+                               // may throw.
+  // Contains information about implicit control flow in this loop's blocks.
+  mutable ImplicitControlFlowTracking ICF;
+  // Contains information about instruction that may possibly write memory.
+  mutable MemoryWriteTracking MW;
+
+public:
+  virtual bool blockMayThrow(const BasicBlock *BB) const;
+
+  virtual bool anyBlockMayThrow() const;
+
+  virtual void computeLoopSafetyInfo(const Loop *CurLoop);
+
+  virtual bool isGuaranteedToExecute(const Instruction &Inst,
+                                     const DominatorTree *DT,
+                                     const Loop *CurLoop) const;
+
+  /// Returns true if we could not execute a memory-modifying instruction before
+  /// we enter \p BB under assumption that \p CurLoop is entered.
+  bool doesNotWriteMemoryBefore(const BasicBlock *BB, const Loop *CurLoop)
+      const;
+
+  /// Returns true if we could not execute a memory-modifying instruction before
+  /// we execute \p I under assumption that \p CurLoop is entered.
+  bool doesNotWriteMemoryBefore(const Instruction &I, const Loop *CurLoop)
+      const;
+
+  /// Inform the safety info that we are planning to insert a new instruction
+  /// \p Inst into the basic block \p BB. It will make all cache updates to keep
+  /// it correct after this insertion.
+  void insertInstructionTo(const Instruction *Inst, const BasicBlock *BB);
+
+  /// Inform safety info that we are planning to remove the instruction \p Inst
+  /// from its block. It will make all cache updates to keep it correct after
+  /// this removal.
+  void removeInstruction(const Instruction *Inst);
+
+  ICFLoopSafetyInfo(DominatorTree *DT) : LoopSafetyInfo(), ICF(DT), MW(DT) {};
+
+  virtual ~ICFLoopSafetyInfo() {};
+};
 
 }