[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.
+ *
+ * Implementation Note:
+ * All the classes in this file are designed to be fully inlined as 32-bit
+ * integers.  The goal: to provide a nice, fluent interface for describing
+ * instruction bit operations, with zero runtime cost.  Compare:
+ *
+ *   return (1 << ((insn >> 12) & 0xF)) | (1 << ((insn >> 19) & 0xF));
+ *
+ *   return insn.reg(15,12) + insn.reg(19,16);
+ *
+ * Both lines compile to the same machine code, but the second one is easier
+ * to read, and eliminates a common error (using X in place of 1 << X).
+ *
+ * To this end, keep the following in mind:
+ *  - Avoid virtual methods.
+ *  - Mark all methods as inline.  Small method bodies may be included here,
+ *    but anything nontrivial should go in model-inl.h.
+ *  - Do not declare destructors.  A destructor causes an object to be passed
+ *    on the stack, even when passed by value.  (This may be a GCC bug.)
+ *    Adding a destructor to Instruction slowed the decoder down by 10% on
+ *    gcc 4.3.3.
+ */
+
+#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 operator==(const Register &) const;

[Brad Chen, 2012/05/04 22:49:50]

avoid operator overloading

[petarj, 2012/05/08 14:54:19]

Seen in validator_arm/model.h

+  inline bool operator!=(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 contains_all(RegisterList) const;
+
+  // Checks whether this list contains any of the registers in the operand.
+  inline bool contains_any(RegisterList) const;
+
+  inline bool operator==(RegisterList) const;
+
+  inline const RegisterList operator&(const RegisterList) const;
+
+  // Allow the addition operator access to our bitwise representation.
+  friend const RegisterList operator+(const RegisterList, const RegisterList);
+
+ private:
+  uint32_t _bits;
+};
+
+/*
+ * Returns a new RegisterList that contains the union of two lists.
+ *
+ * This is not a member function to allow implicit conversion of Register.
+ */
+inline const RegisterList operator+(const RegisterList, const RegisterList);
+
+/*
+ * 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