Changeset 102489 in webkit for trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp

Timestamp:

Dec 9, 2011, 4:09:55 PM (13 years ago)

Author:

[email protected]

Message:

DFG's interpretation of rare case profiles should be frequency-based not count-based
​https://bugs.webkit.org/show_bug.cgi?id=74170

Reviewed by Geoff Garen.

DFG optimizes for rare cases only when the rare case counter is above some threshold
and it also constitutes a large enough fraction of total function executions. Also
added some minor debug logic.

• bytecode/CodeBlock.cpp:

(JSC::CodeBlock::CodeBlock):

• bytecode/CodeBlock.h:

(JSC::CodeBlock::likelyToTakeSlowCase):
(JSC::CodeBlock::couldTakeSlowCase):
(JSC::CodeBlock::likelyToTakeSpecialFastCase):
(JSC::CodeBlock::likelyToTakeDeepestSlowCase):
(JSC::CodeBlock::likelyToTakeAnySlowCase):
(JSC::CodeBlock::executionEntryCount):

• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::makeSafe):
(JSC::DFG::ByteCodeParser::makeDivSafe):
(JSC::DFG::ByteCodeParser::handleCall):
(JSC::DFG::ByteCodeParser::parseBlock):

• dfg/DFGDriver.cpp:

(JSC::DFG::compile):

• jit/JIT.cpp:

(JSC::JIT::privateCompile):

• runtime/Heuristics.cpp:

(JSC::Heuristics::initializeHeuristics):

• runtime/Heuristics.h:

File:

• trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp (modified) (8 diffs)

trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp

@@ -68 +68 @@
             m_preservedVars.set(i);
     }
-
+    
     // Parse a full CodeBlock of bytecode.
     bool parse();
@@ -647 +647 @@
             
         case ArithMul:
-            if (m_inlineStackTop->m_profiledBlock->likelyToTakeDeepestSlowCase(m_currentIndex))
+            if (m_inlineStackTop->m_profiledBlock->likelyToTakeDeepestSlowCase(m_currentIndex)) {
+#if DFG_ENABLE(DEBUG_VERBOSE)
+                printf("Making ArithMul @%u take deepest slow case.\n", nodeIndex);
+#endif
                 m_graph[nodeIndex].mergeArithNodeFlags(NodeMayOverflow | NodeMayNegZero);
-            else
+            } else {
+#if DFG_ENABLE(DEBUG_VERBOSE)
+                printf("Making ArithMul @%u take faster slow case.\n", nodeIndex);
+#endif
                 m_graph[nodeIndex].mergeArithNodeFlags(NodeMayNegZero);
+            }
             break;
             
@@ -673 +680 @@
         if (!m_inlineStackTop->m_profiledBlock->likelyToTakeSpecialFastCase(m_currentIndex))
             return nodeIndex;
+        
+#if DFG_ENABLE(DEBUG_VERBOSE)
+        printf("Making %s @%u safe at bc#%u because special fast-case counter is at %u\n", Graph::opName(m_graph[nodeIndex].op), nodeIndex, m_currentIndex, m_inlineStackTop->m_profiledBlock->specialFastCaseProfileForBytecodeOffset(m_currentIndex)->m_counter);
+#endif
         
         m_graph[nodeIndex].mergeArithNodeFlags(NodeMayOverflow | NodeMayNegZero);
@@ -875 +886 @@
             
 #if DFG_ENABLE(DEBUG_VERBOSE)
-    printf("Slow case count for call at @%lu bc#%u: %u.\n", m_graph.size(), m_currentIndex, m_inlineStackTop->m_profiledBlock->rareCaseProfileForBytecodeOffset(m_currentIndex)->m_counter);
+    printf("Slow case count for call at @%lu bc#%u: %u/%u.\n", m_graph.size(), m_currentIndex, m_inlineStackTop->m_profiledBlock->rareCaseProfileForBytecodeOffset(m_currentIndex)->m_counter, m_inlineStackTop->m_profiledBlock->executionEntryCount());
 #endif
             
@@ -1247 +1258 @@
     bool shouldContinueParsing = true;
     
+    Interpreter* interpreter = m_globalData->interpreter;
+    Instruction* instructionsBegin = m_inlineStackTop->m_codeBlock->instructions().begin();
+    unsigned blockBegin = m_currentIndex;
+    
     // If we are the first basic block, introduce markers for arguments. This allows
     // us to track if a use of an argument may use the actual argument passed, as
@@ -1260 +1275 @@
     }
 
-    Interpreter* interpreter = m_globalData->interpreter;
-    Instruction* instructionsBegin = m_inlineStackTop->m_codeBlock->instructions().begin();
-    unsigned blockBegin = m_currentIndex;
     while (true) {
         // Don't extend over jump destinations.
@@ -1691 +1703 @@
             Identifier identifier = m_codeBlock->identifier(identifierNumber);
             StructureStubInfo& stubInfo = m_inlineStackTop->m_profiledBlock->getStubInfo(m_currentIndex);
+            
+#if DFG_ENABLE(DEBUG_VERBOSE)
+            printf("Slow case count for GetById @%lu bc#%u: %u\n", m_graph.size(), m_currentIndex, m_inlineStackTop->m_profiledBlock->rareCaseProfileForBytecodeOffset(m_currentIndex)->m_counter);
+#endif
             
             size_t offset = notFound;
@@ -1782 +1798 @@
             bool alreadyGenerated = false;
             
+#if DFG_ENABLE(DEBUG_VERBOSE)
+            printf("Slow case count for PutById @%lu bc#%u: %u\n", m_graph.size(), m_currentIndex, m_inlineStackTop->m_profiledBlock->rareCaseProfileForBytecodeOffset(m_currentIndex)->m_counter);
+#endif            
+
             if (stubInfo.seen && !m_inlineStackTop->m_profiledBlock->likelyToTakeSlowCase(m_currentIndex)) {
                 switch (stubInfo.accessType) {