Implemented GetSample like POSIX backtrace()

src/sampler.cc

Index: src/sampler.cc
diff --git a/src/sampler.cc b/src/sampler.cc
index 394efeb7640764870b6f768a9d11a1b879955416..890dd79d082275f9c04bbf1df82df2554fcfab64 100644
--- a/src/sampler.cc
+++ b/src/sampler.cc
@@ -4,44 +4,6 @@
 
 #include "src/sampler.h"
 
-#if V8_OS_POSIX && !V8_OS_CYGWIN
-
-#define USE_SIGNALS
-
-#include <errno.h>
-#include <pthread.h>
-#include <signal.h>
-#include <sys/time.h>
-
-#if !V8_OS_QNX && !V8_OS_NACL
-#include <sys/syscall.h>  // NOLINT
-#endif
-
-#if V8_OS_MACOSX
-#include <mach/mach.h>
-// OpenBSD doesn't have <ucontext.h>. ucontext_t lives in <signal.h>
-// and is a typedef for struct sigcontext. There is no uc_mcontext.
-#elif(!V8_OS_ANDROID || defined(__BIONIC_HAVE_UCONTEXT_T)) && \
-    !V8_OS_OPENBSD && !V8_OS_NACL
-#include <ucontext.h>
-#endif
-
-#include <unistd.h>
-
-// GLibc on ARM defines mcontext_t has a typedef for 'struct sigcontext'.
-// Old versions of the C library <signal.h> didn't define the type.
-#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T) && \
-    (defined(__arm__) || defined(__aarch64__)) && \
-    !defined(__BIONIC_HAVE_STRUCT_SIGCONTEXT)
-#include <asm/sigcontext.h>  // NOLINT
-#endif
-
-#elif V8_OS_WIN || V8_OS_CYGWIN
-
-#include "src/base/win32-headers.h"
-
-#endif
-
 #include "src/v8.h"
 
 #include "src/base/platform/platform.h"
@@ -53,111 +15,6 @@
 #include "src/v8threads.h"
 #include "src/vm-state-inl.h"
 
-
-#if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
-
-// Not all versions of Android's C library provide ucontext_t.
-// Detect this and provide custom but compatible definitions. Note that these
-// follow the GLibc naming convention to access register values from
-// mcontext_t.
-//
-// See http://code.google.com/p/android/issues/detail?id=34784
-
-#if defined(__arm__)
-
-typedef struct sigcontext mcontext_t;
-
-typedef struct ucontext {
-  uint32_t uc_flags;
-  struct ucontext* uc_link;
-  stack_t uc_stack;
-  mcontext_t uc_mcontext;
-  // Other fields are not used by V8, don't define them here.
-} ucontext_t;
-
-#elif defined(__aarch64__)
-
-typedef struct sigcontext mcontext_t;
-
-typedef struct ucontext {
-  uint64_t uc_flags;
-  struct ucontext *uc_link;
-  stack_t uc_stack;
-  mcontext_t uc_mcontext;
-  // Other fields are not used by V8, don't define them here.
-} ucontext_t;
-
-#elif defined(__mips__)
-// MIPS version of sigcontext, for Android bionic.
-typedef struct {
-  uint32_t regmask;
-  uint32_t status;
-  uint64_t pc;
-  uint64_t gregs[32];
-  uint64_t fpregs[32];
-  uint32_t acx;
-  uint32_t fpc_csr;
-  uint32_t fpc_eir;
-  uint32_t used_math;
-  uint32_t dsp;
-  uint64_t mdhi;
-  uint64_t mdlo;
-  uint32_t hi1;
-  uint32_t lo1;
-  uint32_t hi2;
-  uint32_t lo2;
-  uint32_t hi3;
-  uint32_t lo3;
-} mcontext_t;
-
-typedef struct ucontext {
-  uint32_t uc_flags;
-  struct ucontext* uc_link;
-  stack_t uc_stack;
-  mcontext_t uc_mcontext;
-  // Other fields are not used by V8, don't define them here.
-} ucontext_t;
-
-#elif defined(__i386__)
-// x86 version for Android.
-typedef struct {
-  uint32_t gregs[19];
-  void* fpregs;
-  uint32_t oldmask;
-  uint32_t cr2;
-} mcontext_t;
-
-typedef uint32_t kernel_sigset_t[2];  // x86 kernel uses 64-bit signal masks
-typedef struct ucontext {
-  uint32_t uc_flags;
-  struct ucontext* uc_link;
-  stack_t uc_stack;
-  mcontext_t uc_mcontext;
-  // Other fields are not used by V8, don't define them here.
-} ucontext_t;
-enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };
-
-#elif defined(__x86_64__)
-// x64 version for Android.
-typedef struct {
-  uint64_t gregs[23];
-  void* fpregs;
-  uint64_t __reserved1[8];
-} mcontext_t;
-
-typedef struct ucontext {
-  uint64_t uc_flags;
-  struct ucontext *uc_link;
-  stack_t uc_stack;
-  mcontext_t uc_mcontext;
-  // Other fields are not used by V8, don't define them here.
-} ucontext_t;
-enum { REG_RBP = 10, REG_RSP = 15, REG_RIP = 16 };
-#endif
-
-#endif  // V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
-
-
 namespace v8 {
 namespace internal {
 
@@ -232,7 +89,7 @@ class SimulatorHelper {
     return simulator_ != NULL;
   }
 
-  inline void FillRegisters(RegisterState* state) {
+  inline void FillRegisters(v8::RegisterState* state) {
 #if V8_TARGET_ARCH_ARM
     state->pc = reinterpret_cast<Address>(simulator_->get_pc());
     state->sp = reinterpret_cast<Address>(simulator_->get_register(
@@ -353,7 +210,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   Sampler* sampler = isolate->logger()->sampler();
   if (sampler == NULL) return;
 
-  RegisterState state;
+  v8::RegisterState state;
 
 #if defined(USE_SIMULATOR)
   SimulatorHelper helper;
@@ -577,10 +434,10 @@ SamplerThread* SamplerThread::instance_ = NULL;
 // StackTracer implementation
 //
 DISABLE_ASAN void TickSample::Init(Isolate* isolate,
-                                   const RegisterState& regs) {
+                                   const v8::RegisterState& regs) {
   DCHECK(isolate->IsInitialized());
   timestamp = base::TimeTicks::HighResolutionNow();
-  pc = regs.pc;
+  pc = reinterpret_cast<Address>(regs.pc);
   state = isolate->current_vm_state();
 
   // Avoid collecting traces while doing GC.
@@ -603,11 +460,14 @@ DISABLE_ASAN void TickSample::Init(Isolate* isolate,
   } else {
     // Sample potential return address value for frameless invocation of
     // stubs (we'll figure out later, if this value makes sense).
-    tos = Memory::Address_at(regs.sp);
+    tos = Memory::Address_at(reinterpret_cast<Address>(regs.sp));
     has_external_callback = false;
   }
 
-  SafeStackFrameIterator it(isolate, regs.fp, regs.sp, js_entry_sp);
+  SafeStackFrameIterator it(isolate,
+                            reinterpret_cast<Address>(regs.fp),
+                            reinterpret_cast<Address>(regs.sp),
+                            js_entry_sp);
   top_frame_type = it.top_frame_type();
   unsigned i = 0;
   while (!it.done() && i < TickSample::kMaxFramesCount) {
@@ -682,7 +542,7 @@ void Sampler::DecreaseProfilingDepth() {
 }
 
 
-void Sampler::SampleStack(const RegisterState& state) {
+void Sampler::SampleStack(const v8::RegisterState& state) {
   TickSample* sample = isolate_->cpu_profiler()->StartTickSample();
   TickSample sample_obj;
   if (sample == NULL) sample = &sample_obj;
@@ -699,6 +559,41 @@ void Sampler::SampleStack(const RegisterState& state) {
 }
 
 
+int Sampler::GetSample(Isolate* isolate,
+                       const v8::RegisterState& state,
+                       void** buffer,
+                       unsigned int depth) {
+  DCHECK(isolate->IsInitialized());
+
+  // Avoid collecting traces while doing GC.
+  if (isolate->current_vm_state() == GC) return -1;
+
+  fprintf(stderr, "sp:%p\nfp:%p\npc:%p\ndepth:%d\n",
+          state.sp,
+          state.fp,
+          state.pc,
+          depth);
+  Address js_entry_sp = isolate->js_entry_sp();
+  if (js_entry_sp == 0) {
+    fprintf(stderr, "js_entry_sp is zero.\n");
+    return 0;  // Not executing JS now.
+  }
+  
+
+  SafeStackFrameIterator it(isolate,
+                            reinterpret_cast<Address>(state.fp),
+                            reinterpret_cast<Address>(state.sp),
+                            js_entry_sp);
+  unsigned i = 0;
+  while (!it.done() && i < depth) {
+    buffer[i++] = it.frame()->pc();
+    it.Advance();
+  }
+  fprintf(stderr, "GetSample returning %d\n", i);
+  return i;
+}
+
+
 #if defined(USE_SIGNALS)
 
 void Sampler::DoSample() {
@@ -725,7 +620,7 @@ void Sampler::DoSample() {
   memset(&context, 0, sizeof(context));
   context.ContextFlags = CONTEXT_FULL;
   if (GetThreadContext(profiled_thread, &context) != 0) {
-    RegisterState state;
+    v8::RegisterState state;
 #if defined(USE_SIMULATOR)
     helper.FillRegisters(&state);
 #else