Bug 1145924 - Ensure JSRuntime is kept in sync with the profiler. (r=djvj)

js/src/jit/JitcodeMap.cpp

@@ -718,6 +718,14 @@ JitcodeGlobalTable::verifySkiplist()
 }
 #endif // DEBUG
 
+void
+JitcodeGlobalTable::setAllEntriesAsExpired(JSRuntime *rt)
+{
+    AutoSuppressProfilerSampling suppressSampling(rt);
+    for (Range r(*this); !r.empty(); r.popFront())
+        r.front()->setAsExpired();
+}
+
 bool
 JitcodeGlobalTable::markIteratively(JSTracer *trc)
 {
@@ -762,7 +770,7 @@ JitcodeGlobalTable::markIteratively(JSTracer *trc)
         // types used by optimizations and scripts used for pc to line number
         // mapping, alive as well.
         if (!entry->isSampled(gen, lapCount)) {
-            entry->setGeneration(UINT32_MAX);
+            entry->setAsExpired();
             if (!entry->baseEntry().isJitcodeMarkedFromAnyThread())
                 continue;
         }

js/src/jit/JitcodeMap.h

@@ -601,6 +601,9 @@ class JitcodeGlobalEntry
     void setGeneration(uint32_t gen) {
         baseEntry().setGeneration(gen);
     }
+    void setAsExpired() {
+        baseEntry().setGeneration(UINT32_MAX);
+    }
     bool isSampled(uint32_t currentGen, uint32_t lapCount) {
         return baseEntry().isSampled(currentGen, lapCount);
     }
@@ -953,6 +956,7 @@ class JitcodeGlobalTable
     void removeEntry(JitcodeGlobalEntry &entry, JitcodeGlobalEntry **prevTower, JSRuntime *rt);
     void releaseEntry(JitcodeGlobalEntry &entry, JitcodeGlobalEntry **prevTower, JSRuntime *rt);
 
+    void setAllEntriesAsExpired(JSRuntime *rt);
     bool markIteratively(JSTracer *trc);
     void sweep(JSRuntime *rt);
 

js/src/vm/Runtime.h

@@ -696,18 +696,34 @@ struct JSRuntime : public JS::shadow::Runtime,
     uint32_t profilerSampleBufferGen() {
         return profilerSampleBufferGen_;
     }
+    void resetProfilerSampleBufferGen() {
+        profilerSampleBufferGen_ = 0;
+    }
     void setProfilerSampleBufferGen(uint32_t gen) {
-        profilerSampleBufferGen_ = gen;
+        // May be called from sampler thread or signal handler; use
+        // compareExchange to make sure we have monotonic increase.
+        for (;;) {
+            uint32_t curGen = profilerSampleBufferGen_;
+            if (curGen >= gen)
+                break;
+
+            if (profilerSampleBufferGen_.compareExchange(curGen, gen))
+                break;
+        }
     }
 
     uint32_t profilerSampleBufferLapCount() {
         MOZ_ASSERT(profilerSampleBufferLapCount_ > 0);
         return profilerSampleBufferLapCount_;
     }
+    void resetProfilerSampleBufferLapCount() {
+        profilerSampleBufferLapCount_ = 1;
+    }
     void updateProfilerSampleBufferLapCount(uint32_t lapCount) {
         MOZ_ASSERT(profilerSampleBufferLapCount_ > 0);
 
-        // Use compareExchange to make sure we have monotonic increase.
+        // May be called from sampler thread or signal handler; use
+        // compareExchange to make sure we have monotonic increase.
         for (;;) {
             uint32_t curLapCount = profilerSampleBufferLapCount_;
             if (curLapCount >= lapCount)

js/src/vm/SPSProfiler.cpp

@@ -14,6 +14,7 @@
 
 #include "jit/BaselineFrame.h"
 #include "jit/BaselineJIT.h"
+#include "jit/JitcodeMap.h"
 #include "jit/JitFrameIterator.h"
 #include "jit/JitFrames.h"
 #include "vm/StringBuffer.h"
@@ -87,6 +88,15 @@ SPSProfiler::enable(bool enabled)
      */
     ReleaseAllJITCode(rt->defaultFreeOp());
 
+    // This function is called when the Gecko profiler makes a new TableTicker
+    // (and thus, a new circular buffer). Set all current entries in the
+    // JitcodeGlobalTable as expired and reset the buffer generation and lap
+    // count.
+    if (rt->hasJitRuntime() && rt->jitRuntime()->hasJitcodeGlobalTable())
+        rt->jitRuntime()->getJitcodeGlobalTable()->setAllEntriesAsExpired(rt);
+    rt->resetProfilerSampleBufferGen();
+    rt->resetProfilerSampleBufferLapCount();
+
     // Ensure that lastProfilingFrame is null before 'enabled' becomes true.
     if (rt->jitActivation) {
         rt->jitActivation->setLastProfilingFrame(nullptr);
@@ -466,8 +476,8 @@ AutoSuppressProfilerSampling::AutoSuppressProfilerSampling(JSRuntime *rt
 
 AutoSuppressProfilerSampling::~AutoSuppressProfilerSampling()
 {
-        if (previouslyEnabled_)
-            rt_->enableProfilerSampling();
+    if (previouslyEnabled_)
+        rt_->enableProfilerSampling();
 }
 
 void *

tools/profiler/TableTicker.cpp

@@ -635,7 +635,10 @@ void mergeStacksIntoProfile(ThreadProfile& aProfile, TickSample* aSample, Native
   uint32_t lapCount = aProfile.bufferGeneration() - startBufferGen;
 
   // Update the JS runtime with the current profile sample buffer generation.
-  if (pseudoStack->mRuntime) {
+  //
+  // Do not do this for synchronous sampling, which create their own
+  // ProfileBuffers.
+  if (!aSample->isSamplingCurrentThread && pseudoStack->mRuntime) {
     JS::UpdateJSRuntimeProfilerSampleBufferGen(pseudoStack->mRuntime,
                                                aProfile.bufferGeneration(),
                                                lapCount);