Changeset 38763 in webkit for trunk/JavaScriptCore/bytecode/Instruction.h

Timestamp:

Nov 25, 2008, 3:07:30 PM (17 years ago)

Author:

[email protected]

Message:

2008-11-24 Gavin Barraclough <​[email protected]>

Reviewed by Geoff Garen.

Polymorpic caching for get by id chain. Similar to the polymorphic caching already implemented
for self and proto accesses (implemented by allowing multiple trampolines to be JIT genertaed,
and linked together) - the get by id chain caching is implemented as a genericization of the
proto list caching, allowing cached access lists to contain a mix of proto and proto chain
accesses (since in JS style inheritance hierarchies you may commonly see a mix of properties
being overridden on the direct prototype, or higher up its prototype chain).

In order to allow this patch to compile there is a fix to appease gcc 4.2 compiler issues
(removing the jumps between fall-through cases in privateExecute).

This patch also removes redundant immediate checking from the reptach code, and fixes a related
memory leak (failure to deallocate trampolines).

~2% progression on v8 tests (bulk on the win on deltablue)

• bytecode/Instruction.h: (JSC::PolymorphicAccessStructureList::PolymorphicStubInfo::): (JSC::PolymorphicAccessStructureList::PolymorphicStubInfo::set): (JSC::PolymorphicAccessStructureList::PolymorphicAccessStructureList): (JSC::PolymorphicAccessStructureList::derefStructures):
• interpreter/Interpreter.cpp: (JSC::countPrototypeChainEntriesAndCheckForProxies): (JSC::Interpreter::tryCacheGetByID): (JSC::Interpreter::privateExecute): (JSC::Interpreter::tryCTICacheGetByID): (JSC::Interpreter::cti_op_get_by_id_self_fail): (JSC::getPolymorphicAccessStructureListSlot): (JSC::Interpreter::cti_op_get_by_id_proto_list):
• interpreter/Interpreter.h:
• jit/JIT.cpp: (JSC::JIT::privateCompileGetByIdProto): (JSC::JIT::privateCompileGetByIdSelfList): (JSC::JIT::privateCompileGetByIdProtoList): (JSC::JIT::privateCompileGetByIdChainList): (JSC::JIT::privateCompileGetByIdChain): (JSC::JIT::privateCompilePatchGetArrayLength):
• jit/JIT.h: (JSC::JIT::compileGetByIdChainList):

File:

• trunk/JavaScriptCore/bytecode/Instruction.h (modified) (2 diffs)

trunk/JavaScriptCore/bytecode/Instruction.h

@@ -45 +45 @@
     struct PolymorphicAccessStructureList {
         struct PolymorphicStubInfo {
+            unsigned cachedOffset : 31;
+            unsigned isChain : 1;
+            void* stubRoutine;
             Structure* base;
-            Structure* proto;
-            int cachedOffset;
-            void* stubRoutine;
-            
-            void set(Structure* _base, Structure* _proto, int _cachedOffset, void* _stubRoutine)
+            union {
+                Structure* proto;
+                StructureChain* chain;
+            } u;
+
+            void set(int _cachedOffset, void* _stubRoutine, Structure* _base)
             {
-                base = _base;
-                proto = _proto;
                 cachedOffset = _cachedOffset;
                 stubRoutine = _stubRoutine;
+                base = _base;
+                u.proto = 0;
+                isChain = false;
+            }
+            
+            void set(int _cachedOffset, void* _stubRoutine, Structure* _base, Structure* _proto)
+            {
+                cachedOffset = _cachedOffset;
+                stubRoutine = _stubRoutine;
+                base = _base;
+                u.proto = _proto;
+                isChain = false;
+            }
+            
+            void set(int _cachedOffset, void* _stubRoutine, Structure* _base, StructureChain* _chain)
+            {
+                cachedOffset = _cachedOffset;
+                stubRoutine = _stubRoutine;
+                base = _base;
+                u.chain = _chain;
+                isChain = true;
             }
         } list[POLYMORPHIC_LIST_CACHE_SIZE];
         
-        PolymorphicAccessStructureList(Structure* firstBase, Structure* firstProto, int cachedOffset, void* stubRoutine)
+        PolymorphicAccessStructureList(int cachedOffset, void* stubRoutine, Structure* firstBase)
         {
-            list[0].set(firstBase, firstProto, cachedOffset, stubRoutine);
+            list[0].set(cachedOffset, stubRoutine, firstBase);
+        }
+
+        PolymorphicAccessStructureList(int cachedOffset, void* stubRoutine, Structure* firstBase, Structure* firstProto)
+        {
+            list[0].set(cachedOffset, stubRoutine, firstBase, firstProto);
+        }
+
+        PolymorphicAccessStructureList(int cachedOffset, void* stubRoutine, Structure* firstBase, StructureChain* firstChain)
+        {
+            list[0].set(cachedOffset, stubRoutine, firstBase, firstChain);
         }
 
@@ -72 +105 @@
                 info.base->deref();
 
-                if (info.proto)
-                    info.proto->deref();
+                if (info.u.proto) {
+                    if (info.isChain)
+                        info.u.chain->deref();
+                    else
+                        info.u.proto->deref();
+                }
 
                 if (info.stubRoutine)