Initial support for emitting unwinding information in perf jitdump.

src/factory.cc

 // Copyright 2014 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.
 
 #include "src/factory.h"
 
 #include "src/allocation-site-scopes.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/conversions.h"
@@ skipping 1408 matching lines @@
 
 Handle<Code> Factory::NewCode(const CodeDesc& desc,
                               Code::Flags flags,
                               Handle<Object> self_ref,
                               bool immovable,
                               bool crankshafted,
                               int prologue_offset,
                               bool is_debug) {
   Handle<ByteArray> reloc_info = NewByteArray(desc.reloc_size, TENURED);
 
+  bool has_unwinding_info = desc.unwinding_info != nullptr;
+  DCHECK((has_unwinding_info && desc.unwinding_info_size > 0) ||
+         (!has_unwinding_info && desc.unwinding_info_size == 0));
+
   // Compute size.
-  int body_size = RoundUp(desc.instr_size, kObjectAlignment);
-  int obj_size = Code::SizeFor(body_size);
+  int body_size = desc.instr_size;
+  if (has_unwinding_info) {
+    body_size =
+        RoundUp(body_size, kInt64Size) + desc.unwinding_info_size + kInt64Size;

[rmcilroy, 2016/06/24 09:45:26]

What's the extra kInt64Size here for? Is that the size of the
unwinding_info_size field? If so, please add a comment.

[Stefano Sanfilippo, 2016/06/24 10:36:37]

Done.

[rmcilroy, 2016/06/24 12:55:25]

There are multiple kInt64Size here so the comment doesn't make it clear it is
the addition not the RoundUp. Could you just add a local
unwinding_info_size_field_size which should make it clear.

[Stefano Sanfilippo, 2016/06/24 13:17:28]

Done.

+  }
+  int obj_size = Code::SizeFor(RoundUp(body_size, kObjectAlignment));
 
   Handle<Code> code = NewCodeRaw(obj_size, immovable);
   DCHECK(!isolate()->heap()->memory_allocator()->code_range()->valid() ||
          isolate()->heap()->memory_allocator()->code_range()->contains(
              code->address()) ||
          obj_size <= isolate()->heap()->code_space()->AreaSize());
 
   // The code object has not been fully initialized yet.  We rely on the
   // fact that no allocation will happen from this point on.
   DisallowHeapAllocation no_gc;
   code->set_gc_metadata(Smi::FromInt(0));
   code->set_ic_age(isolate()->heap()->global_ic_age());
   code->set_instruction_size(desc.instr_size);
   code->set_relocation_info(*reloc_info);
   code->set_flags(flags);
+  code->set_has_unwinding_info(has_unwinding_info);
   code->set_raw_kind_specific_flags1(0);
   code->set_raw_kind_specific_flags2(0);
   code->set_is_crankshafted(crankshafted);
   code->set_deoptimization_data(*empty_fixed_array(), SKIP_WRITE_BARRIER);
   code->set_raw_type_feedback_info(Smi::FromInt(0));
   code->set_next_code_link(*undefined_value());
   code->set_handler_table(*empty_fixed_array(), SKIP_WRITE_BARRIER);
   code->set_prologue_offset(prologue_offset);
   code->set_constant_pool_offset(desc.instr_size - desc.constant_pool_size);
 
@@ skipping 935 matching lines @@
 }
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return value ? true_value() : false_value();
 }
 
 
 }  // namespace internal
 }  // namespace v8