Changeset 38652 in webkit for trunk/JavaScriptCore/bytecode

Timestamp:

Nov 20, 2008, 9:04:19 PM (17 years ago)

Author:

[email protected]

Message:

2008-11-19 Gavin Barraclough <​[email protected]>

Reviewed by Darin Adler.

Add support for (really) polymorphic caching of prototype accesses.

If a cached prototype access misses, cti_op_get_by_id_proto_list is called.
When this occurs the Structure pointers from the instruction stream are copied
off into a new ProtoStubInfo object. A second prototype access trampoline is
generated, and chained onto the first. Subsequent missed call to
cti_op_get_by_id_proto_list_append, which append futher new trampolines, up to
PROTOTYPE_LIST_CACHE_SIZE (currently 4). If any of the misses result in an
access other than to a direct prototype property, list formation is halted (or
for the initial miss, does not take place at all).

Separate fail case functions are provided for each access since this contributes
to the performance progression (enables better processor branch prediction).

Overall this is a near 5% progression on v8, with around 10% wins on richards
and deltablue.

• bytecode/CodeBlock.cpp: (JSC::CodeBlock::dump): (JSC::CodeBlock::derefStructures):
• bytecode/Instruction.h: (JSC::ProtoStructureList::ProtoStubInfo::set): (JSC::ProtoStructureList::ProtoStructureList): (JSC::Instruction::Instruction): (JSC::Instruction::):
• bytecode/Opcode.h:
• interpreter/Interpreter.cpp: (JSC::Interpreter::privateExecute): (JSC::Interpreter::tryCTICacheGetByID): (JSC::Interpreter::cti_op_put_by_id_fail): (JSC::Interpreter::cti_op_get_by_id_self_fail): (JSC::Interpreter::cti_op_get_by_id_proto_list): (JSC::Interpreter::cti_op_get_by_id_proto_list_append): (JSC::Interpreter::cti_op_get_by_id_proto_list_full): (JSC::Interpreter::cti_op_get_by_id_proto_fail): (JSC::Interpreter::cti_op_get_by_id_chain_fail): (JSC::Interpreter::cti_op_get_by_id_array_fail): (JSC::Interpreter::cti_op_get_by_id_string_fail):
• interpreter/Interpreter.h:
• jit/JIT.cpp: (JSC::JIT::privateCompileMainPass): (JSC::JIT::privateCompileGetByIdSelf): (JSC::JIT::privateCompileGetByIdProto): (JSC::JIT::privateCompileGetByIdProtoList): (JSC::JIT::privateCompileGetByIdChain): (JSC::JIT::privateCompileCTIMachineTrampolines): (JSC::JIT::privateCompilePatchGetArrayLength):
• jit/JIT.h: (JSC::JIT::compileGetByIdProtoList):

Location:

trunk/JavaScriptCore/bytecode

Files:

• CodeBlock.cpp (modified) (2 diffs)
• Instruction.h (modified) (4 diffs)
• Opcode.h (modified) (1 diff)

trunk/JavaScriptCore/bytecode/CodeBlock.cpp

@@ -647 +647 @@
             break;
         }
+        case op_get_by_id_proto_list: {
+            printGetByIdOp(location, it, identifiers, "op_get_by_id_proto_list");
+            break;
+        }
         case op_get_by_id_chain: {
             printGetByIdOp(location, it, identifiers, "get_by_id_chain");
@@ -1020 +1024 @@
         return;
     }
-    
+    if (vPC[0].u.opcode == interpreter->getOpcode(op_get_by_id_proto_list)) {
+        PrototypeStructureList* prototypeStructures = vPC[4].u.prototypeStructure;
+        int count = vPC[5].u.operand;
+        for (int i = 0; i < count; ++i) {
+            PrototypeStructureList::ProtoStubInfo& info = prototypeStructures->list[i];
+            ASSERT(info.base);
+            ASSERT(info.proto);
+            ASSERT(info.stubRoutine);
+            info.base->deref();
+            info.proto->deref();
+            WTF::fastFreeExecutable(info.stubRoutine);
+        }
+        return;
+    }
+
     // These instructions don't ref their Structures.
     ASSERT(vPC[0].u.opcode == interpreter->getOpcode(op_get_by_id) || vPC[0].u.opcode == interpreter->getOpcode(op_put_by_id) || vPC[0].u.opcode == interpreter->getOpcode(op_get_by_id_generic) || vPC[0].u.opcode == interpreter->getOpcode(op_put_by_id_generic) || vPC[0].u.opcode == interpreter->getOpcode(op_get_array_length) || vPC[0].u.opcode == interpreter->getOpcode(op_get_string_length));

trunk/JavaScriptCore/bytecode/Instruction.h

@@ -34 +34 @@
 #include <wtf/VectorTraits.h>
 
+#define PROTOTYPE_LIST_CACHE_SIZE 4
+
 namespace JSC {
 
@@ -39 +41 @@
     class Structure;
     class StructureChain;
+
+    // Structure used by op_get_by_id_proto_list instruction to hold data off the main opcode stream.
+    struct PrototypeStructureList {
+        struct ProtoStubInfo {
+            Structure* base;
+            Structure* proto;
+            int cachedOffset;
+            void* stubRoutine;
+            
+            void set(Structure* _base, Structure* _proto, int _cachedOffset, void* _stubRoutine)
+            {
+                base = _base;
+                proto = _proto;
+                cachedOffset = _cachedOffset;
+                stubRoutine = _stubRoutine;
+            }
+        } list[PROTOTYPE_LIST_CACHE_SIZE];
+        
+        PrototypeStructureList(Structure* firstBase, Structure* firstProto, int cachedOffset, void* stubRoutine)
+        {
+            list[0].set(firstBase, firstProto, cachedOffset, stubRoutine);
+        }
+    };
 
     struct Instruction {
@@ -53 +78 @@
         Instruction(StructureChain* structureChain) { u.structureChain = structureChain; }
         Instruction(JSCell* jsCell) { u.jsCell = jsCell; }
+        Instruction(PrototypeStructureList* prototypeStructure) { u.prototypeStructure = prototypeStructure; }
 
         union {
@@ -61 +87 @@
             JSCell* jsCell;
             ResultType::Type resultType;
+            PrototypeStructureList* prototypeStructure;
         } u;
     };

trunk/JavaScriptCore/bytecode/Opcode.h

@@ -103 +103 @@
         macro(op_get_by_id_self) \
         macro(op_get_by_id_proto) \
+        macro(op_get_by_id_proto_list) \
         macro(op_get_by_id_chain) \
         macro(op_get_by_id_generic) \