[prof] export slide offset in profile log

src/base/platform/platform.h

 // Copyright 2012 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.
 
 // This module contains the platform-specific code. This make the rest of the
 // code less dependent on operating system, compilers and runtime libraries.
 // This module does specifically not deal with differences between different
 // processor architecture.
 // The platform classes have the same definition for all platforms. The
 // implementation for a particular platform is put in platform_<os>.cc.
@@ skipping 219 matching lines @@
                                            const char* format, va_list args);
 
   static char* StrChr(char* str, int c);
   static void StrNCpy(char* dest, int length, const char* src, size_t n);
 
   // Support for the profiler.  Can do nothing, in which case ticks
   // occuring in shared libraries will not be properly accounted for.
   struct SharedLibraryAddress {
     SharedLibraryAddress(
         const std::string& library_path, uintptr_t start, uintptr_t end)
-        : library_path(library_path), start(start), end(end) {}
+        : library_path(library_path), start(start), end(end), slide(0) {}
+    SharedLibraryAddress(
+        const std::string& library_path, uintptr_t start, uintptr_t end,
+            uintptr_t slide)
+        : library_path(library_path), start(start), end(end), slide(slide) {}

[noordhuis, 2016/04/30 10:37:10]

I think this should use intptr_t for the slide because it can be negative; text
sections can be mapped before their default load addresses.  Because of
signed-to-unsigned conversion, logging such slides and adding them to function
addresses in tickprocessor.js, produces bogus results.

intptr_t is what _dyld_get_image_vmaddr_slide() returns.  platform-macos.cc
currently gets this wrong, FWIW.

[fedor.indutny, 2016/04/30 19:54:50]

Acknowledged.

 
     std::string library_path;
     uintptr_t start;
     uintptr_t end;
+    uintptr_t slide;
   };
 
   static std::vector<SharedLibraryAddress> GetSharedLibraryAddresses();
 
   // Support for the profiler.  Notifies the external profiling
   // process that a code moving garbage collection starts.  Can do
   // nothing, in which case the code objects must not move (e.g., by
   // using --never-compact) if accurate profiling is desired.
   static void SignalCodeMovingGC();
 
@@ skipping 227 matching lines @@
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_PLATFORM_PLATFORM_H_