js/src/vm/SPSProfiler.cpp
author Terrence Cole <terrence@mozilla.com>
Wed, 28 May 2014 17:34:36 -0700
changeset 185959 57014191cb434d704159cf4ef73086a10cf7f88c
parent 185642 29ca8bc78484630eb38ed9e159552b73e34b9bf5
child 186724 d185d33cfce5abbbb03157af9f471570478476c3
permissions -rw-r--r--
Bug 1013531 - Clarify the naming of the rooting analysis supression guards; r=sfink

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * 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/SPSProfiler.h"

#include "mozilla/DebugOnly.h"

#include "jsnum.h"
#include "jsprf.h"
#include "jsscript.h"

#include "jit/BaselineJIT.h"
#include "vm/StringBuffer.h"

using namespace js;

using mozilla::DebugOnly;

SPSProfiler::SPSProfiler(JSRuntime *rt)
  : rt(rt),
    stack_(nullptr),
    size_(nullptr),
    max_(0),
    slowAssertions(false),
    enabled_(false),
    lock_(nullptr),
    eventMarker_(nullptr)
{
    JS_ASSERT(rt != nullptr);
}

bool
SPSProfiler::init()
{
#ifdef JS_THREADSAFE
    lock_ = PR_NewLock();
    if (lock_ == nullptr)
        return false;
#endif
    return true;
}

SPSProfiler::~SPSProfiler()
{
    if (strings.initialized()) {
        for (ProfileStringMap::Enum e(strings); !e.empty(); e.popFront())
            js_free(const_cast<char *>(e.front().value()));
    }
#ifdef JS_THREADSAFE
    if (lock_)
        PR_DestroyLock(lock_);
#endif
}

void
SPSProfiler::setProfilingStack(ProfileEntry *stack, uint32_t *size, uint32_t max)
{
    AutoSPSLock lock(lock_);
    JS_ASSERT_IF(size_ && *size_ != 0, !enabled());
    if (!strings.initialized())
        strings.init();
    stack_ = stack;
    size_  = size;
    max_   = max;
}

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

void
SPSProfiler::enable(bool enabled)
{
    JS_ASSERT(installed());

    if (enabled_ == enabled)
        return;

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

    enabled_ = enabled;

#ifdef JS_ION
    /* Toggle SPS-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::ToggleBaselineSPS(rt, enabled);
#endif
}

/* Lookup the string for the function/script, creating one if necessary */
const char*
SPSProfiler::profileString(JSScript *script, JSFunction *maybeFun)
{
    AutoSPSLock lock(lock_);
    JS_ASSERT(strings.initialized());
    ProfileStringMap::AddPtr s = strings.lookupForAdd(script);
    if (s)
        return s->value();
    const char *str = allocProfileString(script, maybeFun);
    if (str == nullptr)
        return nullptr;
    if (!strings.add(s, script, str)) {
        js_free(const_cast<char *>(str));
        return nullptr;
    }
    return str;
}

void
SPSProfiler::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.
     */
    AutoSPSLock lock(lock_);
    if (!strings.initialized())
        return;
    if (ProfileStringMap::Ptr entry = strings.lookup(script)) {
        const char *tofree = entry->value();
        strings.remove(entry);
        js_free(const_cast<char *>(tofree));
    }
}

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

bool
SPSProfiler::enter(JSScript *script, JSFunction *maybeFun)
{
    const char *str = profileString(script, maybeFun);
    if (str == nullptr)
        return false;

#ifdef DEBUG
    // In debug builds, assert the JS pseudo frames already on the stack
    // have a non-null pc. Only look at the top frames to avoid quadratic
    // behavior.
    if (*size_ > 0 && *size_ - 1 < max_) {
        size_t start = (*size_ > 4) ? *size_ - 4 : 0;
        for (size_t i = start; i < *size_ - 1; i++)
            MOZ_ASSERT_IF(stack_[i].isJs(), stack_[i].pc() != nullptr);
    }
#endif

    push(str, nullptr, script, script->code(), /* copy = */ true);
    return true;
}

void
SPSProfiler::exit(JSScript *script, JSFunction *maybeFun)
{
    pop();

#ifdef DEBUG
    /* Sanity check to make sure push/pop balanced */
    if (*size_ < max_) {
        const char *str = profileString(script, maybeFun);
        /* Can't fail lookup because we should already be in the set */
        JS_ASSERT(str != nullptr);

        // Bug 822041
        if (!stack_[*size_].isJs()) {
            fprintf(stderr, "--- ABOUT TO FAIL ASSERTION ---\n");
            fprintf(stderr, " stack=%p size=%d/%d\n", (void*) stack_, *size_, max_);
            for (int32_t i = *size_; i >= 0; i--) {
                if (stack_[i].isJs())
                    fprintf(stderr, "  [%d] JS %s\n", i, stack_[i].label());
                else
                    fprintf(stderr, "  [%d] C line %d %s\n", i, stack_[i].line(), stack_[i].label());
            }
        }

        JS_ASSERT(stack_[*size_].isJs());
        JS_ASSERT(stack_[*size_].script() == script);
        JS_ASSERT(strcmp((const char*) stack_[*size_].label(), str) == 0);
        stack_[*size_].setLabel(nullptr);
        stack_[*size_].setPC(nullptr);
    }
#endif
}

void
SPSProfiler::enterNative(const char *string, void *sp)
{
    /* these operations cannot be re-ordered, so volatile-ize operations */
    volatile ProfileEntry *stack = stack_;
    volatile uint32_t *size = size_;
    uint32_t current = *size;

    JS_ASSERT(enabled());
    if (current < max_) {
        stack[current].setLabel(string);
        stack[current].setCppFrame(sp, 0);
    }
    *size = current + 1;
}

void
SPSProfiler::push(const char *string, void *sp, JSScript *script, jsbytecode *pc, bool copy)
{
    JS_ASSERT_IF(sp != nullptr, script == nullptr && pc == nullptr);
    JS_ASSERT_IF(sp == nullptr, script != nullptr && pc != nullptr);

    /* these operations cannot be re-ordered, so volatile-ize operations */
    volatile ProfileEntry *stack = stack_;
    volatile uint32_t *size = size_;
    uint32_t current = *size;

    JS_ASSERT(installed());
    if (current < max_) {
        volatile ProfileEntry &entry = stack[current];
        entry.setLabel(string);

        if (sp != nullptr)
            entry.setCppFrame(sp, 0);
        else
            entry.setJsFrame(script, pc);

        // Track if mLabel needs a copy.
        if (copy)
            entry.setFlag(js::ProfileEntry::FRAME_LABEL_COPY);
        else
            entry.unsetFlag(js::ProfileEntry::FRAME_LABEL_COPY);
    }
    *size = current + 1;
}

void
SPSProfiler::pop()
{
    JS_ASSERT(installed());
    (*size_)--;
    JS_ASSERT(*(int*)size_ >= 0);
}

/*
 * 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.
 */
const char *
SPSProfiler::allocProfileString(JSScript *script, JSFunction *maybeFun)
{
    // Note: this profiler string is regexp-matched by
    // browser/devtools/profiler/cleopatra/js/parserWorker.js.

    // Determine if the function (if any) has an explicit or guessed name.
    bool hasAtom = maybeFun && maybeFun->displayAtom();

    // Get the function name, if any, and its length.
    const jschar *atom = nullptr;
    size_t lenAtom = 0;
    if (hasAtom) {
        atom = maybeFun->displayAtom()->charsZ();
        lenAtom = maybeFun->displayAtom()->length();
    }

    // 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.
    uint64_t lineno = script->lineno();
    size_t lenLineno = 1;
    for (uint64_t i = lineno; i /= 10; lenLineno++);

    // Determine the required buffer size.
    size_t len = lenFilename + lenLineno + 1; // +1 for the ":" separating them.
    if (hasAtom)
        len += lenAtom + 3; // +3 for the " (" and ")" it adds.

    // Allocate the buffer.
    char *cstr = js_pod_malloc<char>(len + 1);
    if (cstr == nullptr)
        return nullptr;

    // Construct the descriptive string.
    DebugOnly<size_t> ret;
    if (hasAtom)
        ret = JS_snprintf(cstr, len + 1, "%hs (%s:%llu)", atom, filename, lineno);
    else
        ret = JS_snprintf(cstr, len + 1, "%s:%llu", filename, lineno);

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

    return cstr;
}

SPSEntryMarker::SPSEntryMarker(JSRuntime *rt
                               MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
    : profiler(&rt->spsProfiler)
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (!profiler->installed()) {
        profiler = nullptr;
        return;
    }
    size_before = *profiler->size_;
    profiler->push("js::RunScript", this, nullptr, nullptr, /* copy = */ false);
}
SPSEntryMarker::~SPSEntryMarker()
{
    if (profiler != nullptr) {
        profiler->pop();
        JS_ASSERT(size_before == *profiler->size_);
    }
}

JS_FRIEND_API(jsbytecode*)
ProfileEntry::pc() const volatile
{
    MOZ_ASSERT(isJs());
    return lineOrPc == NullPCOffset ? nullptr : script()->offsetToPC(lineOrPc);
}

JS_FRIEND_API(void)
ProfileEntry::setPC(jsbytecode *pc) volatile
{
    MOZ_ASSERT(isJs());
    lineOrPc = pc == nullptr ? NullPCOffset : script()->pcToOffset(pc);
}

JS_FRIEND_API(void)
js::SetRuntimeProfilingStack(JSRuntime *rt, ProfileEntry *stack, uint32_t *size, uint32_t max)
{
    rt->spsProfiler.setProfilingStack(stack, size, max);
}

JS_FRIEND_API(void)
js::EnableRuntimeProfilingStack(JSRuntime *rt, bool enabled)
{
    rt->spsProfiler.enable(enabled);
}

JS_FRIEND_API(void)
js::RegisterRuntimeProfilingEventMarker(JSRuntime *rt, void (*fn)(const char *))
{
    JS_ASSERT(rt->spsProfiler.enabled());
    rt->spsProfiler.setEventMarker(fn);
}

JS_FRIEND_API(jsbytecode*)
js::ProfilingGetPC(JSRuntime *rt, JSScript *script, void *ip)
{
    return rt->spsProfiler.ipToPC(script, size_t(ip));
}