GeckoProfiler.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "vm/GeckoProfiler-inl.h"

#include "mozilla/DebugOnly.h"

#include "jsnum.h"

#include "gc/GC.h"
#include "gc/PublicIterators.h"
#include "jit/BaselineFrame.h"
#include "jit/BaselineJIT.h"
#include "jit/JitcodeMap.h"
#include "jit/JitFrames.h"
#include "jit/JitRealm.h"
#include "jit/JSJitFrameIter.h"
#include "js/TraceLoggerAPI.h"
#include "util/StringBuffer.h"
#include "vm/JSScript.h"

#include "gc/Marking-inl.h"

using namespace js;

using mozilla::DebugOnly;

GeckoProfilerThread::GeckoProfilerThread()
    : profilingStack_(nullptr), profilingStackIfEnabled_(nullptr) {}

GeckoProfilerRuntime::GeckoProfilerRuntime(JSRuntime* rt)
    : rt(rt),
      strings(mutexid::GeckoProfilerStrings),
      slowAssertions(false),
      enabled_(false),
      eventMarker_(nullptr) {
  MOZ_ASSERT(rt != nullptr);
}

void GeckoProfilerThread::setProfilingStack(ProfilingStack* profilingStack,
                                            bool enabled) {
  profilingStack_ = profilingStack;
  profilingStackIfEnabled_ = enabled ? profilingStack : nullptr;
}

void GeckoProfilerRuntime::setEventMarker(void (*fn)(const char*)) {
  eventMarker_ = fn;
}

// Get a pointer to the top-most profiling frame, given the exit frame pointer.
static void* GetTopProfilingJitFrame(Activation* act) {
  if (!act || !act->isJit()) {
    return nullptr;
  }

  jit::JitActivation* jitActivation = act->asJit();

  // If there is no exit frame set, just return.
  if (!jitActivation->hasExitFP()) {
    return nullptr;
  }

  // Skip wasm frames that might be in the way.
  OnlyJSJitFrameIter iter(jitActivation);
  if (iter.done()) {
    return nullptr;
  }

  jit::JSJitProfilingFrameIterator jitIter(
      (jit::CommonFrameLayout*)iter.frame().fp());
  MOZ_ASSERT(!jitIter.done());
  return jitIter.fp();
}

void GeckoProfilerRuntime::enable(bool enabled) {
  JSContext* cx = rt->mainContextFromAnyThread();
  MOZ_ASSERT(cx->geckoProfiler().infraInstalled());

  if (enabled_ == enabled) {
    return;
  }

  /*
   * Ensure all future generated code will be instrumented, or that all
   * currently instrumented code is discarded
   */
  ReleaseAllJITCode(rt->defaultFreeOp());

  // This function is called when the Gecko profiler makes a new Sampler
  // (and thus, a new circular buffer). Set all current entries in the
  // JitcodeGlobalTable as expired and reset the buffer range start.
  if (rt->hasJitRuntime() && rt->jitRuntime()->hasJitcodeGlobalTable()) {
    rt->jitRuntime()->getJitcodeGlobalTable()->setAllEntriesAsExpired();
  }
  rt->setProfilerSampleBufferRangeStart(0);

  // Ensure that lastProfilingFrame is null for the main thread.
  if (cx->jitActivation) {
    cx->jitActivation->setLastProfilingFrame(nullptr);
    cx->jitActivation->setLastProfilingCallSite(nullptr);
  }

  // Reset the tracelogger, if toggled on
  JS::ResetTraceLogger();

  enabled_ = enabled;

  /* Toggle Gecko Profiler-related jumps on baseline jitcode.
   * The call to |ReleaseAllJITCode| above will release most baseline jitcode,
   * but not jitcode for scripts with active frames on the stack.  These scripts
   * need to have their profiler state toggled so they behave properly.
   */
  jit::ToggleBaselineProfiling(rt, enabled);

  // Update lastProfilingFrame to point to the top-most JS jit-frame currently
  // on stack.
  if (cx->jitActivation) {
    // Walk through all activations, and set their lastProfilingFrame
    // appropriately.
    if (enabled) {
      Activation* act = cx->activation();
      void* lastProfilingFrame = GetTopProfilingJitFrame(act);

      jit::JitActivation* jitActivation = cx->jitActivation;
      while (jitActivation) {
        jitActivation->setLastProfilingFrame(lastProfilingFrame);
        jitActivation->setLastProfilingCallSite(nullptr);

        jitActivation = jitActivation->prevJitActivation();
        lastProfilingFrame = GetTopProfilingJitFrame(jitActivation);
      }
    } else {
      jit::JitActivation* jitActivation = cx->jitActivation;
      while (jitActivation) {
        jitActivation->setLastProfilingFrame(nullptr);
        jitActivation->setLastProfilingCallSite(nullptr);
        jitActivation = jitActivation->prevJitActivation();
      }
    }
  }

  // WebAssembly code does not need to be released, but profiling string
  // labels have to be generated so that they are available during async
  // profiling stack iteration.
  for (RealmsIter r(rt); !r.done(); r.next()) {
    r->wasm.ensureProfilingLabels(enabled);
  }
}

/* Lookup the string for the function/script, creating one if necessary */
const char* GeckoProfilerRuntime::profileString(JSScript* script,
                                                JSFunction* maybeFun) {
  auto locked = strings.lock();

  ProfileStringMap::AddPtr s = locked->lookupForAdd(script);

  if (!s) {
    auto str = allocProfileString(script, maybeFun);
    if (!str || !locked->add(s, script, std::move(str))) {
      return nullptr;
    }
  }

  return s->value().get();
}

void GeckoProfilerRuntime::onScriptFinalized(JSScript* script) {
  /*
   * This function is called whenever a script is destroyed, regardless of
   * whether profiling has been turned on, so don't invoke a function on an
   * invalid hash set. Also, even if profiling was enabled but then turned
   * off, we still want to remove the string, so no check of enabled() is
   * done.
   */
  auto locked = strings.lock();
  if (ProfileStringMap::Ptr entry = locked->lookup(script)) {
    locked->remove(entry);
  }
}

void GeckoProfilerRuntime::markEvent(const char* event) {
  MOZ_ASSERT(enabled());
  if (eventMarker_) {
    JS::AutoSuppressGCAnalysis nogc;
    eventMarker_(event);
  }
}

bool GeckoProfilerThread::enter(JSContext* cx, JSScript* script,
                                JSFunction* maybeFun) {
  const char* dynamicString =
      cx->runtime()->geckoProfiler().profileString(script, maybeFun);
  if (dynamicString == nullptr) {
    ReportOutOfMemory(cx);
    return false;
  }

#ifdef DEBUG
  // In debug builds, assert the JS profiling stack frames already on the
  // stack have a non-null pc. Only look at the top frames to avoid quadratic
  // behavior.
  uint32_t sp = profilingStack_->stackPointer;
  if (sp > 0 && sp - 1 < profilingStack_->stackCapacity()) {
    size_t start = (sp > 4) ? sp - 4 : 0;
    for (size_t i = start; i < sp - 1; i++) {
      MOZ_ASSERT_IF(profilingStack_->frames[i].isJsFrame(),
                    profilingStack_->frames[i].pc());
    }
  }
#endif

  profilingStack_->pushJsFrame("", dynamicString, script, script->code());
  return true;
}

void GeckoProfilerThread::exit(JSScript* script, JSFunction* maybeFun) {
  profilingStack_->pop();

#ifdef DEBUG
  /* Sanity check to make sure push/pop balanced */
  uint32_t sp = profilingStack_->stackPointer;
  if (sp < profilingStack_->stackCapacity()) {
    JSRuntime* rt = script->runtimeFromMainThread();
    const char* dynamicString =
        rt->geckoProfiler().profileString(script, maybeFun);
    /* Can't fail lookup because we should already be in the set */
    MOZ_ASSERT(dynamicString);

    // Bug 822041
    if (!profilingStack_->frames[sp].isJsFrame()) {
      fprintf(stderr, "--- ABOUT TO FAIL ASSERTION ---\n");
      fprintf(stderr, " frames=%p size=%u/%u\n", (void*)profilingStack_->frames,
              uint32_t(profilingStack_->stackPointer),
              profilingStack_->stackCapacity());
      for (int32_t i = sp; i >= 0; i--) {
        ProfilingStackFrame& frame = profilingStack_->frames[i];
        if (frame.isJsFrame()) {
          fprintf(stderr, "  [%d] JS %s\n", i, frame.dynamicString());
        } else {
          fprintf(stderr, "  [%d] Label %s\n", i, frame.dynamicString());
        }
      }
    }

    ProfilingStackFrame& frame = profilingStack_->frames[sp];
    MOZ_ASSERT(frame.isJsFrame());
    MOZ_ASSERT(frame.script() == script);
    MOZ_ASSERT(strcmp((const char*)frame.dynamicString(), dynamicString) == 0);
  }
#endif
}

/*
 * Serializes the script/function pair into a "descriptive string" which is
 * allowed to fail. This function cannot trigger a GC because it could finalize
 * some scripts, resize the hash table of profile strings, and invalidate the
 * AddPtr held while invoking allocProfileString.
 */
UniqueChars GeckoProfilerRuntime::allocProfileString(JSScript* script,
                                                     JSFunction* maybeFun) {
  // Note: this profiler string is regexp-matched by
  // devtools/client/profiler/cleopatra/js/parserWorker.js.

  // Get the function name, if any.
  JSAtom* atom = maybeFun ? maybeFun->displayAtom() : nullptr;

  // Get the script filename, if any, and its length.
  const char* filename = script->filename();
  if (filename == nullptr) {
    filename = "<unknown>";
  }
  size_t lenFilename = strlen(filename);

  // Get the line number and its length as a string.
  uint32_t lineno = script->lineno();
  size_t lenLineno = 1;
  for (uint32_t i = lineno; i /= 10; lenLineno++)
    ;

  // Get the column number and its length as a string.
  uint32_t column = script->column();
  size_t lenColumn = 1;
  for (uint32_t i = column; i /= 10; lenColumn++)
    ;

  // Determine the required buffer size.
  size_t len = lenFilename + 1 + lenLineno + 1 +
               lenColumn;  // +1 for each separator colon, ":".
  if (atom) {
    len += JS::GetDeflatedUTF8StringLength(atom) +
           3;  // +3 for the " (" and ")" it adds.
  }

  // Allocate the buffer.
  UniqueChars cstr(js_pod_malloc<char>(len + 1));
  if (!cstr) {
    return nullptr;
  }

  // Construct the descriptive string.
  DebugOnly<size_t> ret;
  if (atom) {
    UniqueChars atomStr = StringToNewUTF8CharsZ(nullptr, *atom);
    if (!atomStr) {
      return nullptr;
    }

    ret = snprintf(cstr.get(), len + 1, "%s (%s:%" PRIu32 ":%" PRIu32 ")",
                   atomStr.get(), filename, lineno, column);
  } else {
    ret = snprintf(cstr.get(), len + 1, "%s:%" PRIu32 ":%" PRIu32, filename,
                   lineno, column);
  }

  MOZ_ASSERT(ret == len, "Computed length should match actual length!");

  return cstr;
}

void GeckoProfilerThread::trace(JSTracer* trc) {
  if (profilingStack_) {
    size_t size = profilingStack_->stackSize();
    for (size_t i = 0; i < size; i++) {
      profilingStack_->frames[i].trace(trc);
    }
  }
}

void GeckoProfilerRuntime::fixupStringsMapAfterMovingGC() {
  auto locked = strings.lock();
  for (ProfileStringMap::Enum e(locked.get()); !e.empty(); e.popFront()) {
    JSScript* script = e.front().key();
    if (IsForwarded(script)) {
      script = Forwarded(script);
      e.rekeyFront(script);
    }
  }
}

#ifdef JSGC_HASH_TABLE_CHECKS
void GeckoProfilerRuntime::checkStringsMapAfterMovingGC() {
  auto locked = strings.lock();
  for (auto r = locked->all(); !r.empty(); r.popFront()) {
    JSScript* script = r.front().key();
    CheckGCThingAfterMovingGC(script);
    auto ptr = locked->lookup(script);
    MOZ_RELEASE_ASSERT(ptr.found() && &*ptr == &r.front());
  }
}
#endif

void ProfilingStackFrame::trace(JSTracer* trc) {
  if (isJsFrame()) {
    JSScript* s = rawScript();
    TraceNullableRoot(trc, &s, "ProfilingStackFrame script");
    spOrScript = s;
  }
}

GeckoProfilerBaselineOSRMarker::GeckoProfilerBaselineOSRMarker(
    JSContext* cx,
    bool hasProfilerFrame MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
    : profiler(&cx->geckoProfiler()) {
  MOZ_GUARD_OBJECT_NOTIFIER_INIT;
  if (!hasProfilerFrame || !cx->runtime()->geckoProfiler().enabled()) {
    profiler = nullptr;
    return;
  }

  uint32_t sp = profiler->profilingStack_->stackPointer;
  if (sp >= profiler->profilingStack_->stackCapacity()) {
    profiler = nullptr;
    return;
  }

  spBefore_ = sp;
  if (sp == 0) {
    return;
  }

  ProfilingStackFrame& frame = profiler->profilingStack_->frames[sp - 1];
  MOZ_ASSERT(!frame.isOSRFrame());
  frame.setIsOSRFrame(true);
}

GeckoProfilerBaselineOSRMarker::~GeckoProfilerBaselineOSRMarker() {
  if (profiler == nullptr) {
    return;
  }

  uint32_t sp = profiler->stackPointer();
  MOZ_ASSERT(spBefore_ == sp);
  if (sp == 0) {
    return;
  }

  ProfilingStackFrame& frame = profiler->stack()[sp - 1];
  MOZ_ASSERT(frame.isOSRFrame());
  frame.setIsOSRFrame(false);
}

JS_PUBLIC_API JSScript* ProfilingStackFrame::script() const {
  MOZ_ASSERT(isJsFrame());
  auto script = reinterpret_cast<JSScript*>(spOrScript.operator void*());
  if (!script) {
    return nullptr;
  }

  // If profiling is supressed then we can't trust the script pointers to be
  // valid as they could be in the process of being moved by a compacting GC
  // (although it's still OK to get the runtime from them).
  JSContext* cx = script->runtimeFromAnyThread()->mainContextFromAnyThread();
  if (!cx->isProfilerSamplingEnabled()) {
    return nullptr;
  }

  MOZ_ASSERT(!IsForwarded(script));
  return script;
}

JS_FRIEND_API jsbytecode* ProfilingStackFrame::pc() const {
  MOZ_ASSERT(isJsFrame());
  if (pcOffsetIfJS_ == NullPCOffset) {
    return nullptr;
  }

  JSScript* script = this->script();
  return script ? script->offsetToPC(pcOffsetIfJS_) : nullptr;
}

/* static */ int32_t ProfilingStackFrame::pcToOffset(JSScript* aScript,
                                                     jsbytecode* aPc) {
  return aPc ? aScript->pcToOffset(aPc) : NullPCOffset;
}

void ProfilingStackFrame::setPC(jsbytecode* pc) {
  MOZ_ASSERT(isJsFrame());
  JSScript* script = this->script();
  MOZ_ASSERT(
      script);  // This should not be called while profiling is suppressed.
  pcOffsetIfJS_ = pcToOffset(script, pc);
}

JS_FRIEND_API void js::SetContextProfilingStack(
    JSContext* cx, ProfilingStack* profilingStack) {
  cx->geckoProfiler().setProfilingStack(
      profilingStack, cx->runtime()->geckoProfiler().enabled());
}

JS_FRIEND_API void js::EnableContextProfilingStack(JSContext* cx,
                                                   bool enabled) {
  cx->geckoProfiler().enable(enabled);
  cx->runtime()->geckoProfiler().enable(enabled);
}

JS_FRIEND_API void js::RegisterContextProfilingEventMarker(
    JSContext* cx, void (*fn)(const char*)) {
  MOZ_ASSERT(cx->runtime()->geckoProfiler().enabled());
  cx->runtime()->geckoProfiler().setEventMarker(fn);
}

AutoSuppressProfilerSampling::AutoSuppressProfilerSampling(
    JSContext* cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
    : cx_(cx), previouslyEnabled_(cx->isProfilerSamplingEnabled()) {
  MOZ_GUARD_OBJECT_NOTIFIER_INIT;
  if (previouslyEnabled_) {
    cx_->disableProfilerSampling();
  }
}

AutoSuppressProfilerSampling::~AutoSuppressProfilerSampling() {
  if (previouslyEnabled_) {
    cx_->enableProfilerSampling();
  }
}