Update prebuilt Clang to match Android kernel.

Bug: 132428451
Change-Id: I8f6e2cb23f381fc0c02ddea99b867e58e925e5be
diff --git a/linux-x64/clang/include/llvm/MCA/HardwareUnits/RetireControlUnit.h b/linux-x64/clang/include/llvm/MCA/HardwareUnits/RetireControlUnit.h
new file mode 100644
index 0000000..0629014
--- /dev/null
+++ b/linux-x64/clang/include/llvm/MCA/HardwareUnits/RetireControlUnit.h
@@ -0,0 +1,103 @@
+//===---------------------- RetireControlUnit.h -----------------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+///
+/// This file simulates the hardware responsible for retiring instructions.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MCA_RETIRE_CONTROL_UNIT_H
+#define LLVM_MCA_RETIRE_CONTROL_UNIT_H
+
+#include "llvm/MC/MCSchedule.h"
+#include "llvm/MCA/HardwareUnits/HardwareUnit.h"
+#include "llvm/MCA/Instruction.h"
+#include <vector>
+
+namespace llvm {
+namespace mca {
+
+/// This class tracks which instructions are in-flight (i.e., dispatched but not
+/// retired) in the OoO backend.
+//
+/// This class checks on every cycle if/which instructions can be retired.
+/// Instructions are retired in program order.
+/// In the event of an instruction being retired, the pipeline that owns
+/// this RetireControlUnit (RCU) gets notified.
+///
+/// On instruction retired, register updates are all architecturally
+/// committed, and any physicall registers previously allocated for the
+/// retired instruction are freed.
+struct RetireControlUnit : public HardwareUnit {
+  // A RUToken is created by the RCU for every instruction dispatched to the
+  // schedulers.  These "tokens" are managed by the RCU in its token Queue.
+  //
+  // On every cycle ('cycleEvent'), the RCU iterates through the token queue
+  // looking for any token with its 'Executed' flag set.  If a token has that
+  // flag set, then the instruction has reached the write-back stage and will
+  // be retired by the RCU.
+  //
+  // 'NumSlots' represents the number of entries consumed by the instruction in
+  // the reorder buffer. Those entries will become available again once the
+  // instruction is retired.
+  //
+  // Note that the size of the reorder buffer is defined by the scheduling
+  // model via field 'NumMicroOpBufferSize'.
+  struct RUToken {
+    InstRef IR;
+    unsigned NumSlots; // Slots reserved to this instruction.
+    bool Executed;     // True if the instruction is past the WB stage.
+  };
+
+private:
+  unsigned NextAvailableSlotIdx;
+  unsigned CurrentInstructionSlotIdx;
+  unsigned AvailableSlots;
+  unsigned MaxRetirePerCycle; // 0 means no limit.
+  std::vector<RUToken> Queue;
+
+public:
+  RetireControlUnit(const MCSchedModel &SM);
+
+  bool isEmpty() const { return AvailableSlots == Queue.size(); }
+  bool isAvailable(unsigned Quantity = 1) const {
+    // Some instructions may declare a number of uOps which exceeds the size
+    // of the reorder buffer. To avoid problems, cap the amount of slots to
+    // the size of the reorder buffer.
+    Quantity = std::min(Quantity, static_cast<unsigned>(Queue.size()));
+
+    // Further normalize the number of micro opcodes for instructions that
+    // declare zero opcodes. This should match the behavior of method
+    // reserveSlot().
+    Quantity = std::max(Quantity, 1U);
+    return AvailableSlots >= Quantity;
+  }
+
+  unsigned getMaxRetirePerCycle() const { return MaxRetirePerCycle; }
+
+  // Reserves a number of slots, and returns a new token.
+  unsigned reserveSlot(const InstRef &IS, unsigned NumMicroOps);
+
+  // Return the current token from the RCU's circular token queue.
+  const RUToken &peekCurrentToken() const;
+
+  // Advance the pointer to the next token in the circular token queue.
+  void consumeCurrentToken();
+
+  // Update the RCU token to represent the executed state.
+  void onInstructionExecuted(unsigned TokenID);
+
+#ifndef NDEBUG
+  void dump() const;
+#endif
+};
+
+} // namespace mca
+} // namespace llvm
+
+#endif // LLVM_MCA_RETIRE_CONTROL_UNIT_H