Remove default monomorphic check code from functions and stubs that do not need it.

runtime/vm/object.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_OBJECT_H_
 #define RUNTIME_VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 4121 matching lines @@
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(ObjectPool, Object);
   friend class Class;
   friend class Object;
   friend class RawObjectPool;
 };
 
 
 class Instructions : public Object {
  public:
-  intptr_t size() const { return raw_ptr()->size_; }  // Excludes HeaderSize().
+  // Excludes HeaderSize().
+  intptr_t size() const { return abs(raw_ptr()->size_); }

[Vyacheslav Egorov (Google), 2016/11/10 13:30:49]

Please add a comment to RawInstructions::size_ that it can be negative in
raw_object.h

It's a very nice neat trick - but it's utterly confusing that size_ can be
negative, so this needs to be well documented.

A much more maintainable approach would be to rename size_ to size_and_flags_
and store flag using bitfields helpers. 

+  bool HasSingleEntryPoint() const { return raw_ptr()->size_ >= 0; }
 
   uword PayloadStart() const {
     return PayloadStart(raw());
   }
+  uword CheckedEntryPoint() const {
+    return CheckedEntryPoint(raw());
+  }
   uword UncheckedEntryPoint() const {
     return UncheckedEntryPoint(raw());
   }
-  uword CheckedEntryPoint() const {
-    return CheckedEntryPoint(raw());
-  }
   static uword PayloadStart(RawInstructions* instr) {
     return reinterpret_cast<uword>(instr->ptr()) + HeaderSize();
   }
 
 #if defined(TARGET_ARCH_IA32)
   static const intptr_t kCheckedEntryOffset = 0;
   static const intptr_t kUncheckedEntryOffset = 0;
 #elif defined(TARGET_ARCH_X64)
   static const intptr_t kCheckedEntryOffset = 16;
   static const intptr_t kUncheckedEntryOffset = 38;
 #elif defined(TARGET_ARCH_ARM)
   static const intptr_t kCheckedEntryOffset = 8;
   static const intptr_t kUncheckedEntryOffset = 32;
 #elif defined(TARGET_ARCH_ARM64)
   static const intptr_t kCheckedEntryOffset = 16;
   static const intptr_t kUncheckedEntryOffset = 40;
 #elif defined(TARGET_ARCH_MIPS)
   static const intptr_t kCheckedEntryOffset = 12;
   static const intptr_t kUncheckedEntryOffset = 52;
 #elif defined(TARGET_ARCH_DBC)
   static const intptr_t kCheckedEntryOffset = 0;
   static const intptr_t kUncheckedEntryOffset = 0;
 #else
 #error Missing entry offsets for current architecture
 #endif
 
+  static uword CheckedEntryPoint(RawInstructions* instr) {
+    uword entry = PayloadStart(instr);
+    if (instr->ptr()->size_ < 0) {

[Vyacheslav Egorov (Google), 2016/11/10 13:30:49]

I suggest having helper:

static bool HasSingleEntryPoint(RawIntructions* instr);

and using it here and below (and above) instead of magical expression. 

This way if we decide to refactor how this sort of flags are stored - we would
not need to search all code base for size_ < 0, size_ > 0 comparisons. 

+      entry += kCheckedEntryOffset;
+    }
+    return entry;
+  }
   static uword UncheckedEntryPoint(RawInstructions* instr) {
-    return PayloadStart(instr) + kUncheckedEntryOffset;
-  }
-  static uword CheckedEntryPoint(RawInstructions* instr) {
-    return PayloadStart(instr) + kCheckedEntryOffset;
+    uword entry = PayloadStart(instr);
+    if (instr->ptr()->size_ < 0) {
+      entry += kUncheckedEntryOffset;
+    }
+    return entry;
   }
 
   static const intptr_t kMaxElements = (kMaxInt32 -
                                         (sizeof(RawInstructions) +
                                          sizeof(RawObject) +
                                          (2 * OS::kMaxPreferredCodeAlignment)));
 
   static intptr_t InstanceSize() {
     ASSERT(sizeof(RawInstructions) ==
            OFFSET_OF_RETURNED_VALUE(RawInstructions, data));
     return 0;
   }
 
   static intptr_t InstanceSize(intptr_t size) {
     intptr_t instructions_size = Utils::RoundUp(size,
                                                 OS::PreferredCodeAlignment());
     intptr_t result = instructions_size + HeaderSize();
     ASSERT(result % OS::PreferredCodeAlignment() == 0);
     return result;
   }
 
   static intptr_t HeaderSize() {
     intptr_t alignment = OS::PreferredCodeAlignment();
     return Utils::RoundUp(sizeof(RawInstructions), alignment);
   }
 
-  static RawInstructions* FromUncheckedEntryPoint(uword entry_point) {
+  static RawInstructions* FromPayloadStart(uword payload_start) {
     return reinterpret_cast<RawInstructions*>(
-        entry_point - HeaderSize() - kUncheckedEntryOffset + kHeapObjectTag);
+        payload_start - HeaderSize() + kHeapObjectTag);
   }
 
   bool Equals(const Instructions& other) const {
     if (size() != other.size()) {
       return false;
     }
     NoSafepointScope no_safepoint;
     return memcmp(raw_ptr(), other.raw_ptr(), InstanceSize(size())) == 0;
   }
 
  private:
   void set_size(intptr_t size) const {
     StoreNonPointer(&raw_ptr()->size_, size);
   }
 
   // New is a private method as RawInstruction and RawCode objects should
   // only be created using the Code::FinalizeCode method. This method creates
   // the RawInstruction and RawCode objects, sets up the pointer offsets
   // and links the two in a GC safe manner.
-  static RawInstructions* New(intptr_t size);
+  static RawInstructions* New(intptr_t size, bool has_single_entry_point);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Instructions, Object);
   friend class Class;
   friend class Code;
   friend class AssemblyInstructionsWriter;
   friend class BlobInstructionsWriter;
 };
 
 
 class LocalVarDescriptors : public Object {
@@ skipping 439 matching lines @@
   bool is_optimized() const {
     return OptimizedBit::decode(raw_ptr()->state_bits_);
   }
   void set_is_optimized(bool value) const;
   bool is_alive() const {
     return AliveBit::decode(raw_ptr()->state_bits_);
   }
   void set_is_alive(bool value) const;
 
   uword PayloadStart() const {
-    return Instructions::PayloadStart(instructions());
+    const Instructions& instr = Instructions::Handle(instructions());
+    return instr.PayloadStart();
   }
   uword UncheckedEntryPoint() const {
-    return Instructions::UncheckedEntryPoint(instructions());
+    const Instructions& instr = Instructions::Handle(instructions());
+    return instr.UncheckedEntryPoint();
   }
   uword CheckedEntryPoint() const {
-    return Instructions::CheckedEntryPoint(instructions());
+    const Instructions& instr = Instructions::Handle(instructions());
+    return instr.CheckedEntryPoint();
   }
   intptr_t Size() const {
     const Instructions& instr = Instructions::Handle(instructions());
     return instr.size();
   }
   RawObjectPool* GetObjectPool() const {
     return object_pool();
   }
   bool ContainsInstructionAt(uword addr) const {
     const Instructions& instr = Instructions::Handle(instructions());
@@ skipping 4302 matching lines @@
 
 inline void TypeArguments::SetHash(intptr_t value) const {
   // This is only safe because we create a new Smi, which does not cause
   // heap allocation.
   StoreSmi(&raw_ptr()->hash_, Smi::New(value));
 }
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_OBJECT_H_