On Thu, Sep 28, 2017, at 08:51 PM, Nicholas Nethercote wrote:
> I sometimes want to know the memory layout of a class/struct. Having all
> the fields together makes that a *lot* easier.
Note that gdb's ptype command can help with this using "/m" which avoids
printing methods. (And of course one can use gdb's python magic to do
even cooler things if you want to see where there's wasted space, etc.)
So, like:
$ gdb OBJDIR/dist/bin/libxul.so
(gdb) ptype/m JSContext
type = struct JSContext : public JS::RootingContext, public
js::MallocProvider<JSContext> {
private:
js::UnprotectedData runtime_;
js::WriteOnceData kind_;
js::WriteOnceData threadNative_;
js::ThreadLocalData helperThread_;
js::ThreadLocalData options_;
js::ThreadLocalData arenas_;
protected:
js::ThreadLocalData enterCompartmentDepth_;
private:
static JS::Error reportedError;
static JS::OOM reportedOOM;
js::ThreadLocalData yieldCallback_;
public:
js::ThreadLocalData jitActivation;
js::ThreadLocalData regexpStack;
js::ThreadLocalData activation_;
js::Activation * volatile profilingActivation_;
private:
js::ThreadLocalData interpreterStack_;
public:
const uintptr_t nativeStackBase;
js::ThreadLocalData nativeStackQuota[3];
js::ThreadLocalData entryMonitor;
js::ThreadLocalData noExecuteDebuggerTop;
bool handlingSegFault;
js::ThreadLocalData activityCallback;
js::ThreadLocalData activityCallbackArg;
js::ThreadLocalData requestDepth;
private:
js::ThreadLocalData autoFlushICache_;
public:
js::ThreadLocalData dtoaState;
js::ThreadLocalData heapState;
js::ThreadLocalData suppressGC;
js::ThreadLocalData enableAccessValidation;
js::ThreadLocalData inUnsafeRegion;
js::ThreadLocalData generationalDisabled;
js::ThreadLocalData compactingDisabledCount;
js::ThreadLocalData keepAtoms;
private:
js::ThreadLocalData frontendCollectionPool_;
mozilla::Atomic<bool, (mozilla::MemoryOrdering)2, void>
suppressProfilerSampling;
js::UnprotectedData geckoProfiler_;
public:
static const size_t TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE;
private:
js::ThreadLocalData tempLifoAlloc_;
public:
js::ThreadLocalData debuggerMutations;
js::ThreadLocalData propertyRemovals;
js::ThreadLocalData ionPcScriptCache;
private:
js::ThreadLocalData throwing;
js::ThreadLocalData unwrappedException_;
js::ThreadLocalData overRecursed_;
js::ThreadLocalData propagatingForcedReturn_;
js::ThreadLocalData liveVolatileJitFrameIter_;
public:
js::ThreadLocalData reportGranularity;
js::ThreadLocalData resolvingList;
js::ThreadLocalData generatingError;
private:
js::ThreadLocalData cycleDetectorVector_;
public:
js::UnprotectedData data;
js::ThreadLocalData outstandingRequests;
js::ThreadLocalData jitIsBroken;
private:
js::ThreadLocalData asyncStackForNewActivations_;
public:
js::ThreadLocalData asyncCauseForNewActivations;
js::ThreadLocalData asyncCallIsExplicit;
private:
js::ThreadLocalData interruptCallbacks_;
public:
js::ThreadLocalData interruptCallbackDisabled;
mozilla::Atomic<unsigned int, (mozilla::MemoryOrdering)0, void>
interrupt_;
mozilla::Atomic<unsigned int, (mozilla::MemoryOrdering)0, void>
interruptRegExpJit_;
private:
mozilla::Atomic<bool, (mozilla::MemoryOrdering)2, void>
handlingJitInterrupt_;
public:
js::FutexThread fx;
js::ThreadLocalData osrTempData_;
js::ThreadLocalData ionReturnOverride_;
mozilla::Atomic<unsigned long, (mozilla::MemoryOrdering)0, void>
jitStackLimit;
js::ThreadLocalData jitStackLimitNoInterrupt;
js::ThreadLocalData getIncumbentGlobalCallback;
js::ThreadLocalData enqueuePromiseJobCallback;
js::ThreadLocalData enqueuePromiseJobCallbackData;
js::ThreadLocalData jobQueue;
js::ThreadLocalData drainingJobQueue;
js::ThreadLocalData stopDrainingJobQueue;
js::ThreadLocalData promiseRejectionTrackerCallback;
js::ThreadLocalData promiseRejectionTrackerCallbackData;
typedef js::Vector InterruptCallbackVector;
}
Andrew
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