VM: Clean up and fix bugs in instructions patterns

runtime/vm/instructions_x64.h

Index: runtime/vm/instructions_x64.h
diff --git a/runtime/vm/instructions_x64.h b/runtime/vm/instructions_x64.h
index 8f5cda401c937f11b0772e480893035575398583..4c4aae833deaf66594d7c7f48adeebf5ae450fd3 100644
--- a/runtime/vm/instructions_x64.h
+++ b/runtime/vm/instructions_x64.h
@@ -20,27 +20,26 @@ class RawClass;
 class Immediate;
 class RawObject;
 
-// Abstract class for all instruction pattern classes.
-class InstructionPattern : public ValueObject {
+
+intptr_t IndexFromPPLoad(uword start);
+
+
+// Template class for all instruction pattern classes.
+// P has to specify a static pattern and a pattern length method.
+template<class P> class InstructionPattern : public ValueObject {
  public:
   explicit InstructionPattern(uword pc) : start_(pc) {
     ASSERT(pc != 0);
   }
-  virtual ~InstructionPattern() {}
 
   // Call to check if the instruction pattern at 'pc' match the instruction.
-  virtual bool IsValid() const {
-    return TestBytesWith(pattern(), pattern_length_in_bytes());
+  // 'P::pattern()' returns the expected byte pattern in form of an integer
+  // array with length of 'P::pattern_length_in_bytes()'. A '-1' element means
+  // 'any byte'.
+  bool IsValid() const {
+    return TestBytesWith(P::pattern(), P::pattern_length_in_bytes());
   }
 
-  // 'pattern' returns the expected byte pattern in form of an integer array
-  // with length of 'pattern_length_in_bytes'. A '-1' element means 'any byte'.
-  virtual const int* pattern() const = 0;
-  virtual int pattern_length_in_bytes() const = 0;
-
-  static intptr_t IndexFromPPLoad(uword start);
-  static intptr_t OffsetFromPPIndex(intptr_t index);
-
  protected:
   uword start() const { return start_; }
 
@@ -48,7 +47,17 @@ class InstructionPattern : public ValueObject {
   // Returns true if the 'num_bytes' bytes at 'start_' correspond to
   // array of integers 'data'. 'data' elements are either a byte or -1, which
   // represents any byte.
-  bool TestBytesWith(const int* data, int num_bytes) const;
+  bool TestBytesWith(const int* data, int num_bytes) const {
+    ASSERT(data != NULL);
+    const uint8_t* byte_array = reinterpret_cast<const uint8_t*>(start_);
+    for (int i = 0; i < num_bytes; i++) {
+      // Skip comparison for data[i] < 0.
+      if ((data[i] >= 0) && (byte_array[i] != (0xFF & data[i]))) {
+        return false;
+      }
+    }
+    return true;
+  }
 
   const uword start_;
 
@@ -56,23 +65,24 @@ class InstructionPattern : public ValueObject {
 };
 
 
-class JumpPattern : public InstructionPattern {
+class JumpPattern : public InstructionPattern<JumpPattern> {
  public:
   JumpPattern(uword pc, const Code& code)
       : InstructionPattern(pc),
         object_pool_(ObjectPool::Handle(code.GetObjectPool())) {}
-  static int InstructionLength() {
-    return kLengthInBytes;
-  }
+
   uword TargetAddress() const;
   void SetTargetAddress(uword new_target) const;
-  virtual int pattern_length_in_bytes() const {
-    return kLengthInBytes;
-  }
 
   static const int kLengthInBytes = 7;
+  static int pattern_length_in_bytes() { return kLengthInBytes; }
+  static const int* pattern() {
+    //  07: 41 ff a7 imm32  jmpq [reg + off]
+    static const int kJumpPattern[kLengthInBytes] =
+        {0x41, 0xFF, -1, -1, -1, -1, -1};
+    return kJumpPattern;
+  }
  private:
-  virtual const int* pattern() const;
   const ObjectPool& object_pool_;
 
   DISALLOW_COPY_AND_ASSIGN(JumpPattern);
@@ -80,33 +90,34 @@ class JumpPattern : public InstructionPattern {
 
 
 // 5 byte call instruction.
-class ShortCallPattern : public InstructionPattern {
+class ShortCallPattern : public InstructionPattern<ShortCallPattern> {
  public:
   explicit ShortCallPattern(uword pc) : InstructionPattern(pc) {}
-  static int InstructionLength() {
-    return kLengthInBytes;
-  }
-
-  virtual int pattern_length_in_bytes() const {
-    return kLengthInBytes;
-  }
 
   void SetTargetAddress(uword new_target) const;
 
+  static int pattern_length_in_bytes() { return kLengthInBytes; }
+  static const int* pattern() {
+    static const int kCallPattern[kLengthInBytes] = {0xE8, -1, -1, -1, -1};
+    return kCallPattern;
+  }
+
  private:
   static const int kLengthInBytes = 5;
-  virtual const int* pattern() const;
-
   DISALLOW_COPY_AND_ASSIGN(ShortCallPattern);
 };
 
 
-class ReturnPattern : public InstructionPattern {
+class ReturnPattern : public InstructionPattern<ReturnPattern> {
  public:
   explicit ReturnPattern(uword pc) : InstructionPattern(pc) {}
 
-  virtual const int* pattern() const;
-  virtual int pattern_length_in_bytes() const { return kLengthInBytes; }
+  static const int* pattern() {
+    static const int kReturnPattern[kLengthInBytes] = { 0xC3 };
+    return kReturnPattern;
+  }
+
+  static int pattern_length_in_bytes() { return kLengthInBytes; }
 
  private:
   static const int kLengthInBytes = 1;
@@ -115,12 +126,17 @@ class ReturnPattern : public InstructionPattern {
 
 // push rbp
 // mov rbp, rsp
-class ProloguePattern : public InstructionPattern {
+class ProloguePattern : public InstructionPattern<ProloguePattern> {
  public:
   explicit ProloguePattern(uword pc) : InstructionPattern(pc) {}
 
-  virtual const int* pattern() const;
-  virtual int pattern_length_in_bytes() const { return kLengthInBytes; }
+  static const int* pattern() {
+    static const int kProloguePattern[kLengthInBytes] =
+        { 0x55, 0x48, 0x89, 0xe5 };
+    return kProloguePattern;
+  }
+
+  static int pattern_length_in_bytes() { return kLengthInBytes; }
 
  private:
   static const int kLengthInBytes = 4;
@@ -128,12 +144,18 @@ class ProloguePattern : public InstructionPattern {
 
 
 // mov rbp, rsp
-class SetFramePointerPattern : public InstructionPattern {
+class SetFramePointerPattern :
+    public InstructionPattern<SetFramePointerPattern> {
  public:
   explicit SetFramePointerPattern(uword pc) : InstructionPattern(pc) {}
 
-  virtual const int* pattern() const;
-  virtual int pattern_length_in_bytes() const { return kLengthInBytes; }
+  static const int* pattern() {
+    static const int kFramePointerPattern[kLengthInBytes] =
+        { 0x48, 0x89, 0xe5 };
+    return kFramePointerPattern;
+  }
+
+  static int pattern_length_in_bytes() { return kLengthInBytes; }
 
  private:
   static const int kLengthInBytes = 3;