Initial support for emitting unwinding information in perf jitdump.

src/objects.cc

 // 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.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <sstream>
 
@@ skipping 13450 matching lines @@
 
 
 void Code::Relocate(intptr_t delta) {
   for (RelocIterator it(this, RelocInfo::kApplyMask); !it.done(); it.next()) {
     it.rinfo()->apply(delta);
   }
   Assembler::FlushICache(GetIsolate(), instruction_start(), instruction_size());
 }
 
 
 void Code::CopyFrom(const CodeDesc& desc) {

[rmcilroy, 2016/06/21 13:47:43]

Please add a cctest which tests this function both with and without passing
unwinding_info, checking that the code object is structured properly (no need to
create valid assembly code, just pass some easy to check bytes in the CodeDesc
and check they all go into the correct place. Also add a cctest that NewCode
sizes code objects appropriately.

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

Done.

   // copy code
   CopyBytes(instruction_start(), desc.buffer,
             static_cast<size_t>(desc.instr_size));
 
+  // copy unwinding info, if any
+  if (desc.unwinding_info && desc.unwinding_info_size > 0) {
+    // pad to 2**3 boundary

[rmcilroy, 2016/06/21 13:47:43]

please write number of bytes instead of 2**3.

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

Done.

+    static const byte padding[8] = {0};
+    int padding_size = ((desc.instr_size + 7) & (~7)) - desc.instr_size;

[rmcilroy, 2016/06/21 13:47:43]

I don't think it's necessary to copy zero's into the padding here, just leave it
as it is since it should never be read.

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

Done.

+    CopyBytes(instruction_end(), padding, padding_size);
+
+    uint64_t unwinding_info_size = desc.unwinding_info_size;
+    CopyBytes(RoundUp(instruction_end(), kInt64Size),

[rmcilroy, 2016/06/21 13:47:43]

Just use set_unwinding_size

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

Done.

+              reinterpret_cast<byte*>(&unwinding_info_size),
+              sizeof(unwinding_info_size));
+    CopyBytes(unwinding_info_start(), desc.unwinding_info,
+              static_cast<size_t>(desc.unwinding_info_size));
+  }
+
   // copy reloc info
   CopyBytes(relocation_start(),
             desc.buffer + desc.buffer_size - desc.reloc_size,
             static_cast<size_t>(desc.reloc_size));
 
   // unbox handles and relocate
   intptr_t delta = instruction_start() - desc.buffer;
   int mode_mask = RelocInfo::kCodeTargetMask |
                   RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
                   RelocInfo::ModeMask(RelocInfo::CELL) |
@@ skipping 5372 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8