Initial support for emitting unwinding information in perf jitdump.

src/objects.h

 // Copyright 2015 the V8 project 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 V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/assert-scope.h"
@@ skipping 4892 matching lines @@
   static const char* ICState2String(InlineCacheState state);
   static void PrintExtraICState(std::ostream& os,  // NOLINT
                                 Kind kind, ExtraICState extra);
   void Disassemble(const char* name, std::ostream& os);  // NOLINT
 #endif  // ENABLE_DISASSEMBLER
 
   // [instruction_size]: Size of the native instructions
   inline int instruction_size() const;
   inline void set_instruction_size(int value);
 
+  // [unwinding_info_size]: Size of the unwinding information.
+  inline int unwinding_info_size() const;
+  inline void set_unwinding_info_size(int value);
+
   // [relocation_info]: Code relocation information
   DECL_ACCESSORS(relocation_info, ByteArray)
   void InvalidateRelocation();
   void InvalidateEmbeddedObjects();
 
   // [handler_table]: Fixed array containing offsets of exception handlers.
   DECL_ACCESSORS(handler_table, FixedArray)
 
   // [deoptimization_data]: Array containing data for deopt.
   DECL_ACCESSORS(deoptimization_data, FixedArray)
@@ skipping 55 matching lines @@
   inline bool is_compare_ic_stub();
   inline bool is_to_boolean_ic_stub();
   inline bool is_optimized_code();
   inline bool is_wasm_code();
 
   inline bool IsCodeStubOrIC();
 
   inline void set_raw_kind_specific_flags1(int value);
   inline void set_raw_kind_specific_flags2(int value);
 
+  // [has_unwinding_info]: Whether this code object has unwinding information.
+  // If it doesn't, unwinding_information_start() will point to invalid data.
+  DECL_BOOLEAN_ACCESSORS(has_unwinding_info)

[rmcilroy, 2016/06/21 13:47:44]

nit - move down to near unwinding_info_start.

Also, please add a simple diagram showing the layout of the unwinding info
(including that the first address is the length).

[Stefano Sanfilippo, 2016/06/23 15:23:44]

Done.

+
   // Testers for interpreter builtins.
   inline bool is_interpreter_trampoline_builtin();
 
   // [is_crankshafted]: For kind STUB or ICs, tells whether or not a code
   // object was generated by either the hydrogen or the TurboFan optimizing
   // compiler (but it may not be an optimized function).
   inline bool is_crankshafted();
   inline bool is_hydrogen_stub();  // Crankshafted, but not a function.
   inline void set_is_crankshafted(bool value);
 
@@ skipping 120 matching lines @@
 
   // Convert an entry address into an object.
   static inline Object* GetObjectFromEntryAddress(Address location_of_address);
 
   // Returns the address of the first instruction.
   inline byte* instruction_start();
 
   // Returns the address right after the last instruction.
   inline byte* instruction_end();
 
   // Returns the size of the instructions, padding, and relocation information.

[rmcilroy, 2016/06/21 13:47:44]

update comment.

[Stefano Sanfilippo, 2016/06/23 15:23:44]

Done.

   inline int body_size();
 
   // Returns the size of code and its metadata. This includes the size of code
   // relocation information, deoptimization data and handler table.
   inline int SizeIncludingMetadata();
 
   // Returns the address of the first relocation info (read backwards!).
   inline byte* relocation_start();
 
+  // Returns the address of the unwinding information.

[rmcilroy, 2016/06/21 13:47:44]

information, if any.

[Stefano Sanfilippo, 2016/06/23 15:23:44]

Done.

+  inline byte* unwinding_info_start();
+
+  // Returns the address past the end of the unwinding information.

[rmcilroy, 2016/06/21 13:47:44]

/s/past/right after/

[Stefano Sanfilippo, 2016/06/23 15:23:44]

Done.

+  inline byte* unwinding_info_end();
+
   // Code entry point.
   inline byte* entry();
 
   // Returns true if pc is inside this object's instructions.
   inline bool contains(byte* pc);
 
   // Relocate the code by delta bytes. Called to signal that this code
   // object has been moved by delta bytes.
   void Relocate(intptr_t delta);
 
@@ skipping 128 matching lines @@
       : public BitField<bool, 2, 1> {};
   // Bit 3 in this bitfield is unused.
   class ProfilerTicksField : public BitField<int, 4, 28> {};
 
   // Flags layout.  BitField<type, shift, size>.
   class ICStateField : public BitField<InlineCacheState, 0, 3> {};
   class CacheHolderField
       : public BitField<CacheHolderFlag, ICStateField::kNext, 2> {};
   class KindField : public BitField<Kind, CacheHolderField::kNext, 5> {};
   STATIC_ASSERT(NUMBER_OF_KINDS <= KindField::kMax);
-  class ExtraICStateField : public BitField<ExtraICState, KindField::kNext,
-                                            PlatformSmiTagging::kSmiValueSize -
-                                                KindField::kNext + 1> {};
+  class HasUnwindingInfoField : public BitField<bool, KindField::kNext, 1> {};
+  class ExtraICStateField
+      : public BitField<ExtraICState, HasUnwindingInfoField::kNext,
+                        PlatformSmiTagging::kSmiValueSize -
+                            HasUnwindingInfoField::kNext + 1> {};
 
   // KindSpecificFlags1 layout (STUB, BUILTIN and OPTIMIZED_FUNCTION)
   static const int kStackSlotsFirstBit = 0;
   static const int kStackSlotsBitCount = 24;
   static const int kMarkedForDeoptimizationBit =
       kStackSlotsFirstBit + kStackSlotsBitCount;
   static const int kIsTurbofannedBit = kMarkedForDeoptimizationBit + 1;
   static const int kCanHaveWeakObjects = kIsTurbofannedBit + 1;
 
   STATIC_ASSERT(kStackSlotsFirstBit + kStackSlotsBitCount <= 32);
@@ skipping 5507 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_