Changeset 49004 in webkit for trunk/JavaScriptCore/runtime/JSValue.h

Timestamp:

Oct 1, 2009, 4:32:48 PM (16 years ago)

Author:

[email protected]

Message:

Take one branch instead of two to test for JSValue().

Patch by Geoffrey Garen <​[email protected]> on 2009-10-01
Reviewed by Sam Weinig.

1.1% SunSpider speedup.

• jit/JITCall.cpp:

(JSC::JIT::compileOpCall):

• jit/JITOpcodes.cpp:

(JSC::JIT::emit_op_to_jsnumber):
(JSC::JIT::emit_op_create_arguments):

• jit/JITPropertyAccess.cpp:

(JSC::JIT::emitSlow_op_get_by_val):
(JSC::JIT::emit_op_put_by_val): Test for the empty value tag, instead
of testing for the cell tag with a 0 payload.

• runtime/JSValue.cpp:

(JSC::JSValue::description): Added support for dumping the new empty value,
and deleted values, in debug builds.

• runtime/JSValue.h:

(JSC::JSValue::JSValue()): Construct JSValue() with the empty value tag.

(JSC::JSValue::JSValue(JSCell*)): Convert null pointer to the empty value
tag, to avoid having two different c++ versions of null / empty.

(JSC::JSValue::operator bool): Test for the empty value tag, instead
of testing for the cell tag with a 0 payload.

File:

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

trunk/JavaScriptCore/runtime/JSValue.h

@@ -214 +214 @@
         enum { NullTag =         0xfffffffb };
         enum { UndefinedTag =    0xfffffffa };
-        enum { DeletedValueTag = 0xfffffff9 };
+        enum { EmptyValueTag =   0xfffffff9 };
+        enum { DeletedValueTag = 0xfffffff8 };
 
         enum { LowestTag =  DeletedValueTag };
@@ -428 +429 @@
     inline JSValue::JSValue()
     {
-        u.asBits.tag = CellTag;
+        u.asBits.tag = EmptyValueTag;
         u.asBits.payload = 0;
     }
@@ -464 +465 @@
     inline JSValue::JSValue(JSCell* ptr)
     {
-        u.asBits.tag = CellTag;
+        if (ptr)
+            u.asBits.tag = CellTag;
+        else
+            u.asBits.tag = EmptyValueTag;
         u.asBits.payload = reinterpret_cast<int32_t>(ptr);
     }
@@ -470 +474 @@
     inline JSValue::JSValue(const JSCell* ptr)
     {
-        u.asBits.tag = CellTag;
+        if (ptr)
+            u.asBits.tag = CellTag;
+        else
+            u.asBits.tag = EmptyValueTag;
         u.asBits.payload = reinterpret_cast<int32_t>(const_cast<JSCell*>(ptr));
     }
@@ -476 +483 @@
     inline JSValue::operator bool() const
     {
-        return u.asBits.payload || tag() != CellTag;
+        ASSERT(tag() != DeletedValueTag);
+        return tag() != EmptyValueTag;
     }