Changeset 49065 in webkit for trunk/JavaScriptCore/runtime/JSArray.h

Timestamp:

Oct 3, 2009, 10:01:14 AM (16 years ago)

Author:

[email protected]

Message:

Removed the concept of a "fast access cutoff" in arrays, because it
punished some patterns of array access too much, and made things too
complex for inlining in some cases.

Patch by Geoffrey Garen <​[email protected]> on 2009-10-02
Reviewed by Sam Weinig.

1.3% speedup on SunSpider.

• jit/JITOpcodes.cpp:

(JSC::JIT::emitSlow_op_get_by_val):
(JSC::JIT::emitSlow_op_put_by_val):

• jit/JITPropertyAccess.cpp:

(JSC::JIT::emit_op_get_by_val):
(JSC::JIT::emitSlow_op_get_by_val):
(JSC::JIT::emit_op_put_by_val):
(JSC::JIT::emitSlow_op_put_by_val):

• jit/JITStubs.cpp:
• jit/JITStubs.h:

(JSC::): Check m_vectorLength instead of m_fastAccessCutoff when
getting / putting from / to an array. Inline putting past the end of
the array.

• runtime/JSArray.cpp:

(JSC::JSArray::JSArray):
(JSC::JSArray::getOwnPropertySlot):
(JSC::JSArray::getOwnPropertyDescriptor):
(JSC::JSArray::put):
(JSC::JSArray::putSlowCase):
(JSC::JSArray::deleteProperty):
(JSC::JSArray::getOwnPropertyNames):
(JSC::JSArray::increaseVectorLength):
(JSC::JSArray::setLength):
(JSC::JSArray::pop):
(JSC::JSArray::push):
(JSC::JSArray::sort):
(JSC::JSArray::fillArgList):
(JSC::JSArray::copyToRegisters):
(JSC::JSArray::compactForSorting):
(JSC::JSArray::checkConsistency):

• runtime/JSArray.h:

(JSC::JSArray::canGetIndex):
(JSC::JSArray::canSetIndex):
(JSC::JSArray::setIndex):
(JSC::JSArray::markChildrenDirect): Removed m_fastAccessCutoff, and
replaced with checks for JSValue() to detect reads and writes from / to
uninitialized parts of the array.

File:

• trunk/JavaScriptCore/runtime/JSArray.h (modified) (5 diffs)

trunk/JavaScriptCore/runtime/JSArray.h

@@ -30 +30 @@
     struct ArrayStorage {
         unsigned m_length;
-        unsigned m_vectorLength;
         unsigned m_numValuesInVector;
         SparseArrayValueMap* m_sparseValueMap;
@@ -64 +63 @@
         JSValue pop();
 
-        bool canGetIndex(unsigned i) { return i < m_fastAccessCutoff; }
+        bool canGetIndex(unsigned i) { return i < m_vectorLength && m_storage->m_vector[i]; }
         JSValue getIndex(unsigned i)
         {
@@ -71 +70 @@
         }
 
-        bool canSetIndex(unsigned i) { return i < m_fastAccessCutoff; }
-        JSValue setIndex(unsigned i, JSValue v)
+        bool canSetIndex(unsigned i) { return i < m_vectorLength; }
+        void setIndex(unsigned i, JSValue v)
         {
             ASSERT(canSetIndex(i));
-            return m_storage->m_vector[i] = v;
+            JSValue& x = m_storage->m_vector[i];
+            if (!x) {
+                ++m_storage->m_numValuesInVector;
+                if (i >= m_storage->m_length)
+                    m_storage->m_length = i + 1;
+            }
+            x = v;
         }
 
@@ -111 +116 @@
         void checkConsistency(ConsistencyCheckType = NormalConsistencyCheck);
 
-        unsigned m_fastAccessCutoff;
+        unsigned m_vectorLength;
         ArrayStorage* m_storage;
     };
@@ -140 +145 @@
         ArrayStorage* storage = m_storage;
 
-        unsigned usedVectorLength = std::min(storage->m_length, storage->m_vectorLength);
+        unsigned usedVectorLength = std::min(storage->m_length, m_vectorLength);
         markStack.appendValues(storage->m_vector, usedVectorLength, MayContainNullValues);