Initial support for emitting unwinding information in perf jitdump.

src/mips64/assembler-mips64.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 282 matching lines @@
   EmitForbiddenSlotInstruction();
   DCHECK(pc_ <= reloc_info_writer.pos());  // No overlap.
   // Set up code descriptor.
   desc->buffer = buffer_;
   desc->buffer_size = buffer_size_;
   desc->instr_size = pc_offset();
   desc->reloc_size =
       static_cast<int>((buffer_ + buffer_size_) - reloc_info_writer.pos());
   desc->origin = this;
   desc->constant_pool_size = 0;
+  desc->unwinding_info_size = 0;
+  desc->unwinding_info = nullptr;
 }
 
 
 void Assembler::Align(int m) {
   DCHECK(m >= 4 && base::bits::IsPowerOfTwo32(m));
   EmitForbiddenSlotInstruction();
   while ((pc_offset() & (m - 1)) != 0) {
     nop();
   }
 }
@@ skipping 3108 matching lines @@
   if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
     Assembler::FlushICache(isolate, pc, 4 * Assembler::kInstrSize);
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64