Initial support for emitting unwinding information in perf jitdump.

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index 3c5f4161fd00f8c162a8c0c21903cceeb8e9260f..f4e3e5dcfbfdd9e20c7cdb9e9baa836870560d61 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -1426,9 +1426,17 @@ Handle<Code> Factory::NewCode(const CodeDesc& desc,
                               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() ||
@@ -1444,6 +1452,7 @@ Handle<Code> Factory::NewCode(const CodeDesc& desc,
   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);