Change BKPT and UDF encodings on ARM.

src/trusted/validator_arm/actual_classes.h

Index: src/trusted/validator_arm/actual_classes.h
diff --git a/src/trusted/validator_arm/actual_classes.h b/src/trusted/validator_arm/actual_classes.h
index f2e202d1e51354ec7b66ac8cd5b02f7ca78d1946..2cfb107d9ad0fc73cfa87ef410e997dd42ab313d 100644
--- a/src/trusted/validator_arm/actual_classes.h
+++ b/src/trusted/validator_arm/actual_classes.h
@@ -718,27 +718,27 @@ class EffectiveNoOp : public OldClassDecoder {
   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: