[webkit-changes] [99375] trunk/Source/JavaScriptCore

Sun, 06 Nov 2011 03:55:08 -0800

Title: [99375] trunk/Source/_javascript_Core
Revision
99375
Author
[email protected]
Date
2011-11-06 03:54:59 -0800 (Sun, 06 Nov 2011)

Log Message

Value profiling should just use two buckets
https://bugs.webkit.org/show_bug.cgi?id=71619

Reviewed by Gavin Barraclough.
        
Added one more configuration options (like Heuristics::minimumOptimizationDelay),
improved debugging in JIT optimization support, changed the number of buckets
in the value profile from 9 to 2, and wrote a more optimal value profiling path
in the old JIT to take advantage of this. It's still possible to play around with
larger numbers of buckets, and we should probably keep this for a little while
until we convince ourselves that using just two buckets is the right call.

* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::shouldOptimizeNow):
* bytecode/ValueProfile.h:
* jit/JITInlineMethods.h:
(JSC::JIT::emitValueProfilingSite):
* jit/JITStubs.cpp:
(JSC::DEFINE_STUB_FUNCTION):
* runtime/Heuristics.cpp:
(JSC::Heuristics::initializeHeuristics):
* runtime/Heuristics.h:

Modified Paths

Diff

Modified: trunk/Source/_javascript_Core/ChangeLog (99374 => 99375)


--- trunk/Source/_javascript_Core/ChangeLog	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/ChangeLog	2011-11-06 11:54:59 UTC (rev 99375)
@@ -1,3 +1,28 @@
+2011-11-05  Filip Pizlo  <[email protected]>
+
+        Value profiling should just use two buckets
+        https://bugs.webkit.org/show_bug.cgi?id=71619
+
+        Reviewed by Gavin Barraclough.
+        
+        Added one more configuration options (like Heuristics::minimumOptimizationDelay),
+        improved debugging in JIT optimization support, changed the number of buckets
+        in the value profile from 9 to 2, and wrote a more optimal value profiling path
+        in the old JIT to take advantage of this. It's still possible to play around with
+        larger numbers of buckets, and we should probably keep this for a little while
+        until we convince ourselves that using just two buckets is the right call.
+
+        * bytecode/CodeBlock.cpp:
+        (JSC::CodeBlock::shouldOptimizeNow):
+        * bytecode/ValueProfile.h:
+        * jit/JITInlineMethods.h:
+        (JSC::JIT::emitValueProfilingSite):
+        * jit/JITStubs.cpp:
+        (JSC::DEFINE_STUB_FUNCTION):
+        * runtime/Heuristics.cpp:
+        (JSC::Heuristics::initializeHeuristics):
+        * runtime/Heuristics.h:
+
 2011-11-03  Filip Pizlo  <[email protected]>
 
         JSC should be able to sample itself in a more flexible way than just sampling flags

Modified: trunk/Source/_javascript_Core/bytecode/CodeBlock.cpp (99374 => 99375)


--- trunk/Source/_javascript_Core/bytecode/CodeBlock.cpp	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/bytecode/CodeBlock.cpp	2011-11-06 11:54:59 UTC (rev 99375)
@@ -1956,9 +1956,11 @@
 #endif
 
     if ((!numberOfNonArgumentValueProfiles || (double)numberOfLiveNonArgumentValueProfiles / numberOfNonArgumentValueProfiles >= Heuristics::desiredProfileLivenessRate)
-        && (!numberOfValueProfiles() || (double)numberOfSamplesInProfiles / ValueProfile::numberOfBuckets / numberOfValueProfiles() >= Heuristics::desiredProfileFullnessRate))
+        && (!numberOfValueProfiles() || (double)numberOfSamplesInProfiles / ValueProfile::numberOfBuckets / numberOfValueProfiles() >= Heuristics::desiredProfileFullnessRate)
+        && static_cast<unsigned>(m_optimizationDelayCounter) + 1 >= Heuristics::minimumOptimizationDelay)
         return true;
     
+    ASSERT(m_optimizationDelayCounter < std::numeric_limits<uint8_t>::max());
     m_optimizationDelayCounter++;
     optimizeAfterWarmUp();
     return false;

Modified: trunk/Source/_javascript_Core/bytecode/ValueProfile.h (99374 => 99375)


--- trunk/Source/_javascript_Core/bytecode/ValueProfile.h	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/bytecode/ValueProfile.h	2011-11-06 11:54:59 UTC (rev 99375)
@@ -38,7 +38,7 @@
 
 #if ENABLE(VALUE_PROFILER)
 struct ValueProfile {
-    static const unsigned logNumberOfBuckets = 3; // 8 buckets
+    static const unsigned logNumberOfBuckets = 0; // 1 bucket
     static const unsigned numberOfBuckets = 1 << logNumberOfBuckets;
     static const unsigned numberOfSpecFailBuckets = 1;
     static const unsigned bucketIndexMask = numberOfBuckets - 1;

Modified: trunk/Source/_javascript_Core/jit/JITInlineMethods.h (99374 => 99375)


--- trunk/Source/_javascript_Core/jit/JITInlineMethods.h	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/jit/JITInlineMethods.h	2011-11-06 11:54:59 UTC (rev 99375)
@@ -462,6 +462,9 @@
         return;
     
     const RegisterID value = regT0;
+#if USE(JSVALUE32_64)
+    const RegisterID valueTag = regT1;
+#endif
     const RegisterID scratch = regT3;
     
     ValueProfile* valueProfile;
@@ -474,6 +477,19 @@
     
     ASSERT(valueProfile);
     
+    if (ValueProfile::numberOfBuckets == 1) {
+        // We're in a simple configuration: only one bucket, so we can just do a direct
+        // store.
+#if USE(JSVALUE64)
+        storePtr(value, valueProfile->m_buckets);
+#else
+        EncodedValueDescriptor* descriptor = bitwise_cast<EncodedValueDescriptor*>(valueProfile->m_buckets);
+        store32(value, &descriptor->asBits.payload);
+        store32(valueTag, &descriptor->asBits.tag);
+#endif
+        return;
+    }
+    
     if (m_randomGenerator.getUint32() & 1)
         add32(Imm32(1), bucketCounterRegister);
     else
@@ -483,7 +499,6 @@
 #if USE(JSVALUE64)
     storePtr(value, BaseIndex(scratch, bucketCounterRegister, TimesEight));
 #elif USE(JSVALUE32_64)
-    const RegisterID valueTag = regT1;
     store32(value, BaseIndex(scratch, bucketCounterRegister, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload)));
     store32(valueTag, BaseIndex(scratch, bucketCounterRegister, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag)));
 #endif

Modified: trunk/Source/_javascript_Core/jit/JITStubs.cpp (99374 => 99375)


--- trunk/Source/_javascript_Core/jit/JITStubs.cpp	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/jit/JITStubs.cpp	2011-11-06 11:54:59 UTC (rev 99375)
@@ -1958,7 +1958,7 @@
     
     if (void* address = DFG::prepareOSREntry(callFrame, optimizedCodeBlock, bytecodeIndex)) {
 #if ENABLE(JIT_VERBOSE_OSR)
-        printf("Optimizing %p from loop succeeded, performing OSR.\n", codeBlock);
+        printf("Optimizing %p from loop succeeded, performing OSR after a delay of %u.\n", codeBlock, codeBlock->optimizationDelayCounter());
 #endif
 
         codeBlock->optimizeSoon();
@@ -1968,7 +1968,7 @@
     }
     
 #if ENABLE(JIT_VERBOSE_OSR)
-    printf("Optimizing %p from loop succeeded, OSR failed.\n", codeBlock);
+    printf("Optimizing %p from loop succeeded, OSR failed, after a delay of %u.\n", codeBlock, codeBlock->optimizationDelayCounter());
 #endif
 
     // Count the OSR failure as a speculation failure. If this happens a lot, then
@@ -2058,7 +2058,7 @@
     ASSERT(codeBlock->replacement()->getJITType() == JITCode::DFGJIT);
 
 #if ENABLE(JIT_VERBOSE_OSR)
-    printf("Optimizing %p from return succeeded.\n", codeBlock);
+    printf("Optimizing %p from return succeeded after a delay of %u.\n", codeBlock, codeBlock->optimizationDelayCounter());
 #endif
     
     codeBlock->optimizeSoon();

Modified: trunk/Source/_javascript_Core/runtime/Heuristics.cpp (99374 => 99375)


--- trunk/Source/_javascript_Core/runtime/Heuristics.cpp	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/runtime/Heuristics.cpp	2011-11-06 11:54:59 UTC (rev 99375)
@@ -74,6 +74,7 @@
 unsigned reoptimizationRetryCounterMax;
 unsigned reoptimizationRetryCounterStep;
 
+unsigned minimumOptimizationDelay;
 unsigned maximumOptimizationDelay;
 double desiredProfileLivenessRate;
 double desiredProfileFullnessRate;
@@ -157,6 +158,7 @@
 
     SET(reoptimizationRetryCounterStep, 1);
 
+    SET(minimumOptimizationDelay,   1);
     SET(maximumOptimizationDelay,   5);
     SET(desiredProfileLivenessRate, 0.75);
     SET(desiredProfileFullnessRate, 0.35);

Modified: trunk/Source/_javascript_Core/runtime/Heuristics.h (99374 => 99375)


--- trunk/Source/_javascript_Core/runtime/Heuristics.h	2011-11-06 11:39:12 UTC (rev 99374)
+++ trunk/Source/_javascript_Core/runtime/Heuristics.h	2011-11-06 11:54:59 UTC (rev 99375)
@@ -60,6 +60,7 @@
 extern unsigned reoptimizationRetryCounterMax;
 extern unsigned reoptimizationRetryCounterStep;
 
+extern unsigned minimumOptimizationDelay;
 extern unsigned maximumOptimizationDelay;
 extern double desiredProfileLivenessRate;
 extern double desiredProfileFullnessRate;

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