Change BKPT and UDF encodings on ARM.

src/trusted/validator_arm/actual_classes.h

 /*
  * Copyright (c) 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.
  */
 
 #ifndef NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_ACTUAL_CLASSES_H_
 #define NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_ACTUAL_CLASSES_H_
 
 #include "native_client/src/trusted/validator_arm/inst_classes.h"
@@ skipping 700 matching lines @@
 class EffectiveNoOp : public OldClassDecoder {
  public:
   EffectiveNoOp() {}
   virtual SafetyLevel safety(Instruction i) const;
   virtual RegisterList defs(Instruction i) const;
 
  private:
   NACL_DISALLOW_COPY_AND_ASSIGN(EffectiveNoOp);
 };
 
-// Models all instructions that reliably trap, preventing execution from falling
-// through to the next instruction.  Note that roadblocks currently have no
-// special role in the SFI model, so Breakpoints are distinguished below.
-class Roadblock : public OldClassDecoder {
+// UDF
+// Permanently undefined in the ARM ISA.
+class PermanentlyUndefined : public OldClassDecoder {
  public:
-  Roadblock() {}
+  PermanentlyUndefined() {}
   virtual SafetyLevel safety(Instruction i) const;
   virtual RegisterList defs(Instruction i) const;
 
  private:
-  NACL_DISALLOW_COPY_AND_ASSIGN(Roadblock);
+  NACL_DISALLOW_COPY_AND_ASSIGN(PermanentlyUndefined);
 };
 
 // BKPT
 // We model this mostly so we can use it to recognize literal pools -- untrusted
 // code isn't expected to use it, but it's not unsafe, and there are cases where
 // we may generate it.
-class Breakpoint : public Roadblock {
+class Breakpoint : public OldClassDecoder {
  public:
   Breakpoint() {}
   virtual SafetyLevel safety(Instruction i) const;
+  virtual RegisterList defs(Instruction i) const;
   virtual bool is_literal_pool_head(Instruction i) const;
 
  private:
   NACL_DISALLOW_COPY_AND_ASSIGN(Breakpoint);
 };
 
 // Models the Pack/Saturate/Reverse instructions, which
 //  - Write a register identified by 15:12,
 //  - Are not permitted to affect r15,
 //  - Always set flags.
@@ skipping 394 matching lines @@
   virtual RegisterList defs(Instruction i) const;
   virtual bool clears_bits(Instruction i, uint32_t mask) const;
 
  private:
   NACL_DISALLOW_COPY_AND_ASSIGN(Unary1RegisterBitRangeMsbGeLsb);
 };
 
 }  // namespace nacl_arm_dec
 
 #endif  // NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_ARM_ACTUAL_CLASSES_H_