[MIPS] Adding validator for MIPS architecture.

src/trusted/validator_mips/model.h

+/*
+ * Copyright 2012 The Native Client Authors.  All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can
+ * be found in the LICENSE file.
+ * Copyright 2012, Google Inc.
+ */
+
+#ifndef NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_MIPS_MODEL_H
+#define NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_MIPS_MODEL_H
+
+/*
+ * Models instructions and decode results.
+ *
+ * TODO(petarj): This file and the classes have been based on the same named
+ * module within validator_arm folder. The code has been reduced and changed
+ * slightly to accommodate some style issues. There still may be room for
+ * improvement as we have not investigated performance impact of this classes.
+ * Thus, this should be done later and the code should be revisited.
+ */
+
+#include <stdint.h>
+
+namespace nacl_mips_dec {
+
+/*
+ * A value class that names a single register.  We could use a typedef for this,
+ * but it introduces some ambiguity problems because of the implicit conversion
+ * to/from int.
+ *
+ * May be implicitly converted to a single-entry RegisterList (see below).
+ */
+class Register {
+ public:
+  explicit inline Register(uint32_t);
+
+  /*
+   * Produces the bitmask used to represent this register.
+   */
+  inline uint32_t Bitmask() const;
+
+  inline bool Equals(const Register &) const;
+
+ private:
+  uint32_t _number;
+};
+
+const Register kRegisterNone(0);
+
+// Registers with special meaning in our model:
+const Register kRegisterStack(29);
+const Register kRegisterJumpMask(14);       // $t6 = holds mask for jr.
+const Register kRegisterLoadStoreMask(15);  // $t7 = holds mask for load/store.
+const Register kRegisterTls(24);            // $t8 = holds tls index.
+
+const Register kRegisterZero(0);
+
+/*
+ * A collection of Registers.  Used to describe the side effects of operations.
+ *
+ * Note that this is technically a set, not a list -- but RegisterSet is a
+ * well-known term that means something else.
+ */
+class RegisterList {
+ public:
+  /*
+   * Produces a RegisterList that contains the registers specified in the
+   * given bitmask.  To indicate rN, the bitmask must include (1 << N).
+   */
+  explicit inline RegisterList(uint32_t bitmask);
+
+  /*
+   * Produces a RegisterList containing a single register.
+   *
+   * Note that this is an implicit constructor.  This is okay in this case
+   * because
+   *  - It converts between two types that we control,
+   *  - It converts at most one step (no implicit conversions to Register),
+   *  - It inlines to a single machine instruction,
+   *  - The readability gain in inst_classes.cc is large.
+   */
+  inline RegisterList(const Register r);
+
+  /*
+   * Checks whether this list contains the given register.
+   */
+  inline bool operator[](const Register) const;
+
+  // Checks whether this list contains all the registers in the operand.
+  inline bool ContainsAll(RegisterList) const;
+
+  // Checks whether this list contains any of the registers in the operand.
+  inline bool ContainsAny(RegisterList) const;
+
+  inline const RegisterList operator&(const RegisterList) const;
+
+ private:
+  uint32_t _bits;
+};
+
+/*
+ * A list containing every possible register, even some we don't define.
+ * Used exclusively as a bogus scary return value for forbidden instructions.
+ */
+static const RegisterList kRegisterListEverything = RegisterList(-1);
+
+static uint32_t const kReservedRegsBitmask = kRegisterTls.Bitmask()
+                                             + kRegisterJumpMask.Bitmask()
+                                             + kRegisterLoadStoreMask.Bitmask();
+static RegisterList const kRegListReserved = RegisterList(kReservedRegsBitmask);
+
+/*
+ * A 32-bit Mips instruction of unspecified type.
+ *
+ * This class is designed for efficiency:
+ *  - Its public methods for bitfield extraction are short and inline.
+ *  - It has no vtable, so on 32-bit platforms it's exactly the size of the
+ *    instruction it models.
+ */
+class Instruction {
+ public:
+  explicit inline Instruction(uint32_t bits);
+
+  /*
+   * Extracts a range of contiguous bits, right-justifies it, and returns it.
+   * Note that the range follows hardware convention, with the high bit first.
+   */
+  inline uint32_t Bits(int hi, int lo) const;
+
+  /*
+   * A convenience method that's exactly equivalent to
+   *   Register(instruction.bits(hi, lo))
+   *
+   * This sequence is quite common in inst_classes.cc.
+   */
+  inline const Register Reg(int hi, int lo) const;
+
+  /*
+   * Extracts a single bit (0 - 31).
+   */
+  inline bool Bit(int index) const;
+
+  /*
+   * Returns an integer equivalent of this instruction, masked by the given
+   * mask.  Used during decoding to test bitfields.
+   */
+  inline uint32_t operator&(uint32_t) const;
+
+ private:
+  uint32_t _bits;
+};
+
+uint32_t const kInstrSize   = 4;
+uint32_t const kInstrAlign  = 0xFFFFFFFC;
+uint32_t const kBundleAlign = 0xFFFFFFF0;
+
+}  // namespace
+
+// Definitions for our inlined functions.
+#include "native_client/src/trusted/validator_mips/model-inl.h"
+
+#endif  // NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_MIPS_MODEL_H