Changeset 42976 in webkit

Timestamp:

Apr 28, 2009, 5:38:23 PM (16 years ago)

Author:

[email protected]

Message:

Improve performance of string indexing

Reviewed by Geoff Garen

Add a cti_get_by_val_string function to specialise indexing into a string object.
This gives us a slight performance win on a number of string tests.

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• jit/JITStubs.cpp (modified) (2 diffs)
• jit/JITStubs.h (modified) (1 diff)

trunk/JavaScriptCore/ChangeLog

@@ -4 +4 @@
 
         * GNUmakefile.am:
+
+2009-04-28  Oliver Hunt  <[email protected]>
+
+        Reviewed by Geoff Garen.
+
+        Improve performance of string indexing
+
+        Add a cti_get_by_val_string function to specialise indexing into a string object.
+        This gives us a slight performance win on a number of string tests.
+
+        * jit/JITStubs.cpp:
+        (JSC::JITStubs::cti_op_get_by_val):
+        (JSC::JITStubs::cti_op_get_by_val_string):
+        * jit/JITStubs.h:
 
 2009-04-28  Oliver Hunt  <[email protected]>

trunk/JavaScriptCore/jit/JITStubs.cpp

@@ -1127 +1127 @@
             else
                 result = jsArray->JSArray::get(callFrame, i);
-        } else if (isJSString(globalData, baseValue) && asString(baseValue)->canGetIndex(i))
+        } else if (isJSString(globalData, baseValue) && asString(baseValue)->canGetIndex(i)) {
+            // All fast byte array accesses are safe from exceptions so return immediately to avoid exception checks.
+            ctiPatchCallByReturnAddress(STUB_RETURN_ADDRESS, reinterpret_cast<void*>(cti_op_get_by_val_string));
             result = asString(baseValue)->getIndex(ARG_globalData, i);
-        else if (isJSByteArray(globalData, baseValue) && asByteArray(baseValue)->canAccessIndex(i)) {
+        } else if (isJSByteArray(globalData, baseValue) && asByteArray(baseValue)->canAccessIndex(i)) {
             // All fast byte array accesses are safe from exceptions so return immediately to avoid exception checks.
             ctiPatchCallByReturnAddress(STUB_RETURN_ADDRESS, reinterpret_cast<void*>(cti_op_get_by_val_byte_array));
@@ -1143 +1145 @@
     return JSValuePtr::encode(result);
 }
+    
+    JSValueEncodedAsPointer* JITStubs::cti_op_get_by_val_string(STUB_ARGS)
+    {
+        BEGIN_STUB_FUNCTION();
+        
+        CallFrame* callFrame = ARG_callFrame;
+        JSGlobalData* globalData = ARG_globalData;
+        
+        JSValuePtr baseValue = ARG_src1;
+        JSValuePtr subscript = ARG_src2;
+        
+        JSValuePtr result;
+        
+        if (LIKELY(subscript.isUInt32Fast())) {
+            uint32_t i = subscript.getUInt32Fast();
+            if (isJSString(globalData, baseValue) && asString(baseValue)->canGetIndex(i))
+                result = asString(baseValue)->getIndex(ARG_globalData, i);
+            else {
+                result = baseValue.get(callFrame, i);
+                if (!isJSString(globalData, baseValue))
+                    ctiPatchCallByReturnAddress(STUB_RETURN_ADDRESS, reinterpret_cast<void*>(cti_op_get_by_val));
+            }
+        } else {
+            Identifier property(callFrame, subscript.toString(callFrame));
+            result = baseValue.get(callFrame, property);
+        }
+        
+        CHECK_FOR_EXCEPTION_AT_END();
+        return JSValuePtr::encode(result);
+    }
+    
 
 JSValueEncodedAsPointer* JITStubs::cti_op_get_by_val_byte_array(STUB_ARGS)

trunk/JavaScriptCore/jit/JITStubs.h

@@ -129 +129 @@
         static JSValueEncodedAsPointer* JIT_STUB cti_op_get_by_val(STUB_ARGS);
         static JSValueEncodedAsPointer* JIT_STUB cti_op_get_by_val_byte_array(STUB_ARGS);
+        static JSValueEncodedAsPointer* JIT_STUB cti_op_get_by_val_string(STUB_ARGS);
         static JSValueEncodedAsPointer* JIT_STUB cti_op_in(STUB_ARGS);
         static JSValueEncodedAsPointer* JIT_STUB cti_op_instanceof(STUB_ARGS);