Clean up encoding of size and single entry flag in Instructions.

R=vegorov@google.com

Review URL: https://codereview.chromium.org/2490363002 .

runtime/vm/object.cc

@@ -11385,7 +11385,8 @@ RawInstructions* Instructions::New(intptr_t size, bool has_single_entry_point) {
         Object::Allocate(Instructions::kClassId, aligned_size, Heap::kCode);
     NoSafepointScope no_safepoint;
     result ^= raw;
-    result.set_size(has_single_entry_point ? size : -size);
+    result.SetSize(size);
+    result.SetHasSingleEntryPoint(has_single_entry_point);
   }
   return result.raw();
 }
@@ -13765,9 +13766,9 @@ void Code::Disassemble(DisassemblyFormatter* formatter) const {
   const Instructions& instr = Instructions::Handle(instructions());
   uword start = instr.PayloadStart();
   if (formatter == NULL) {
-    Disassembler::Disassemble(start, start + instr.size(), *this);
+    Disassembler::Disassemble(start, start + instr.Size(), *this);
   } else {
-    Disassembler::Disassemble(start, start + instr.size(), formatter, *this);
+    Disassembler::Disassemble(start, start + instr.Size(), formatter, *this);
   }
 #endif
 }
@@ -13996,14 +13997,14 @@ RawCode* Code::FinalizeCode(const char* name,
   // Copy the instructions into the instruction area and apply all fixups.
   // Embedded pointers are still in handles at this point.
   MemoryRegion region(reinterpret_cast<void*>(instrs.PayloadStart()),
-                      instrs.size());
+                      instrs.Size());
   assembler->FinalizeInstructions(region);
-  CPU::FlushICache(instrs.PayloadStart(), instrs.size());
+  CPU::FlushICache(instrs.PayloadStart(), instrs.Size());
 
   code.set_compile_timestamp(OS::GetCurrentMonotonicMicros());
 #ifndef PRODUCT
   CodeObservers::NotifyAll(name, instrs.PayloadStart(),
-                           assembler->prologue_offset(), instrs.size(),
+                           assembler->prologue_offset(), instrs.Size(),
                            optimized);
 #endif
   {

runtime/vm/object.h

@@ -4012,14 +4012,33 @@ class ObjectPool : public Object {
 
 class Instructions : public Object {
  public:
+  enum {
+    kSizePos = 0,
+    kSizeSize = 31,
+    kFlagsPos = kSizePos + kSizeSize,
+    kFlagsSize = 1,  // Currently, only flag is single entry flag.
+  };
+
+  class SizeBits : public BitField<uint32_t, uint32_t, kSizePos, kSizeSize> {};
+  class FlagsBits : public BitField<uint32_t, bool, kFlagsPos, kFlagsSize> {};
+
   // Excludes HeaderSize().
-  intptr_t size() const { return abs(raw_ptr()->size_); }
-  bool HasSingleEntryPoint() const { return raw_ptr()->size_ >= 0; }
+  intptr_t Size() const { return SizeBits::decode(raw_ptr()->size_and_flags_); }
+  static intptr_t Size(const RawInstructions* instr) {
+    return SizeBits::decode(instr->ptr()->size_and_flags_);
+  }
+
+  bool HasSingleEntryPoint() const {
+    return FlagsBits::decode(raw_ptr()->size_and_flags_);
+  }
+  static bool HasSingleEntryPoint(const RawInstructions* instr) {
+    return FlagsBits::decode(instr->ptr()->size_and_flags_);
+  }
 
   uword PayloadStart() const { return PayloadStart(raw()); }
   uword CheckedEntryPoint() const { return CheckedEntryPoint(raw()); }
   uword UncheckedEntryPoint() const { return UncheckedEntryPoint(raw()); }
-  static uword PayloadStart(RawInstructions* instr) {
+  static uword PayloadStart(const RawInstructions* instr) {
     return reinterpret_cast<uword>(instr->ptr()) + HeaderSize();
   }
 
@@ -4045,16 +4064,16 @@ class Instructions : public Object {
 #error Missing entry offsets for current architecture
 #endif
 
-  static uword CheckedEntryPoint(RawInstructions* instr) {
+  static uword CheckedEntryPoint(const RawInstructions* instr) {
     uword entry = PayloadStart(instr);
-    if (instr->ptr()->size_ < 0) {
+    if (!HasSingleEntryPoint(instr)) {
       entry += kCheckedEntryOffset;
     }
     return entry;
   }
-  static uword UncheckedEntryPoint(RawInstructions* instr) {
+  static uword UncheckedEntryPoint(const RawInstructions* instr) {
     uword entry = PayloadStart(instr);
-    if (instr->ptr()->size_ < 0) {
+    if (!HasSingleEntryPoint(instr)) {
       entry += kUncheckedEntryOffset;
     }
     return entry;
@@ -4089,16 +4108,23 @@ class Instructions : public Object {
   }
 
   bool Equals(const Instructions& other) const {
-    if (size() != other.size()) {
+    if (Size() != other.Size()) {
       return false;
     }
     NoSafepointScope no_safepoint;
-    return memcmp(raw_ptr(), other.raw_ptr(), InstanceSize(size())) == 0;
+    return memcmp(raw_ptr(), other.raw_ptr(), InstanceSize(Size())) == 0;
   }
 
  private:
-  void set_size(intptr_t size) const {
-    StoreNonPointer(&raw_ptr()->size_, size);
+  void SetSize(intptr_t value) const {
+    ASSERT(value >= 0);
+    StoreNonPointer(&raw_ptr()->size_and_flags_,
+                    SizeBits::update(value, raw_ptr()->size_and_flags_));
+  }
+
+  void SetHasSingleEntryPoint(bool value) const {
+    StoreNonPointer(&raw_ptr()->size_and_flags_,
+                    FlagsBits::update(value, raw_ptr()->size_and_flags_));
   }
 
   // New is a private method as RawInstruction and RawCode objects should
@@ -4573,13 +4599,13 @@ class Code : public Object {
   }
   intptr_t Size() const {
     const Instructions& instr = Instructions::Handle(instructions());
-    return instr.size();
+    return instr.Size();
   }
   RawObjectPool* GetObjectPool() const { return object_pool(); }
   bool ContainsInstructionAt(uword addr) const {
     const Instructions& instr = Instructions::Handle(instructions());
     const uword offset = addr - instr.PayloadStart();
-    return offset < static_cast<uword>(instr.size());
+    return offset < static_cast<uword>(instr.Size());
   }
 
   // Returns true if there is a debugger breakpoint set in this code object.

runtime/vm/precompiler.h

@@ -139,7 +139,7 @@ class InstructionsKeyValueTrait {
 
   static Value ValueOf(Pair kv) { return kv; }
 
-  static inline intptr_t Hashcode(Key key) { return key->size(); }
+  static inline intptr_t Hashcode(Key key) { return key->Size(); }
 
   static inline bool IsKeyEqual(Pair pair, Key key) {
     return pair->Equals(*key);

runtime/vm/raw_object.cc

@@ -68,7 +68,7 @@ intptr_t RawObject::SizeFromClass() const {
     case kInstructionsCid: {
       const RawInstructions* raw_instructions =
           reinterpret_cast<const RawInstructions*>(this);
-      intptr_t instructions_size = abs(raw_instructions->ptr()->size_);
+      intptr_t instructions_size = Instructions::Size(raw_instructions);
       instance_size = Instructions::InstanceSize(instructions_size);
       break;
     }
@@ -580,15 +580,14 @@ intptr_t RawObjectPool::VisitObjectPoolPointers(RawObjectPool* raw_obj,
 intptr_t RawInstructions::VisitInstructionsPointers(
     RawInstructions* raw_obj,
     ObjectPointerVisitor* visitor) {
-  RawInstructions* obj = raw_obj->ptr();
-  return Instructions::InstanceSize(abs(obj->size_));
+  return Instructions::InstanceSize(Instructions::Size(raw_obj));
 }
 
 
 bool RawInstructions::ContainsPC(RawInstructions* raw_instr, uword pc) {
   uword start_pc =
       reinterpret_cast<uword>(raw_instr->ptr()) + Instructions::HeaderSize();
-  uword end_pc = start_pc + abs(raw_instr->ptr()->size_);
+  uword end_pc = start_pc + Instructions::Size(raw_instr);
   ASSERT(end_pc > start_pc);
   return (pc >= start_pc) && (pc < end_pc);
 }

runtime/vm/raw_object.h

@@ -1161,7 +1161,9 @@ class RawObjectPool : public RawObject {
 class RawInstructions : public RawObject {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Instructions);
 
-  int32_t size_;
+  // Instructions size in bytes and flags.
+  // Currently, only flag indicates 1 or 2 entry points.
+  uint32_t size_and_flags_;
 
   // Variable length data follows here.
   uint8_t* data() { OPEN_ARRAY_START(uint8_t, uint8_t); }

runtime/vm/snapshot.cc

@@ -814,7 +814,7 @@ void AssemblyInstructionsWriter::Write(uint8_t* vmisolate_buffer,
       NoSafepointScope no_safepoint;
       uword beginning = reinterpret_cast<uword>(insns.raw()) - kHeapObjectTag;
       uword entry = beginning + Instructions::HeaderSize();
-      uword payload_size = insns.size();
+      uword payload_size = insns.Size();
       payload_size = Utils::RoundUp(payload_size, OS::PreferredCodeAlignment());
       uword end = entry + payload_size;
 
@@ -945,7 +945,7 @@ void BlobInstructionsWriter::Write(uint8_t* vmisolate_buffer,
       NoSafepointScope no_safepoint;
       uword beginning = reinterpret_cast<uword>(insns.raw()) - kHeapObjectTag;
       uword entry = beginning + Instructions::HeaderSize();
-      uword payload_size = insns.size();
+      uword payload_size = insns.Size();
       payload_size = Utils::RoundUp(payload_size, OS::PreferredCodeAlignment());
       uword end = entry + payload_size;