Revision: 9409
Author: [email protected]
Date: Fri Sep 23 01:00:06 2011
Log: Improve Hydrogen code for accessing undefined/null/Infinity.
In some special (but probably very common) cases we can do better than
loading
from a global cell for these global properties by emitting the corresponding
constant directly. This opens up opportunities for further improvements,
coming
in a separate CL...
Review URL: http://codereview.chromium.org/7992002
http://code.google.com/p/v8/source/detail?r=9409
Modified:
/branches/bleeding_edge/src/factory.cc
/branches/bleeding_edge/src/factory.h
/branches/bleeding_edge/src/heap.cc
/branches/bleeding_edge/src/heap.h
/branches/bleeding_edge/src/hydrogen.cc
/branches/bleeding_edge/src/runtime.cc
=======================================
--- /branches/bleeding_edge/src/factory.cc Thu Sep 22 04:30:04 2011
+++ /branches/bleeding_edge/src/factory.cc Fri Sep 23 01:00:06 2011
@@ -1313,6 +1313,15 @@
*pending_exception = false;
}
}
+
+
+Handle<Object> Factory::GlobalConstantFor(Handle<String> name) {
+ Heap* h = isolate()->heap();
+ if (name->Equals(h->undefined_symbol())) return undefined_value();
+ if (name->Equals(h->nan_symbol())) return nan_value();
+ if (name->Equals(h->infinity_symbol())) return infinity_value();
+ return Handle<Object>::null();
+}
} } // namespace v8::internal
=======================================
--- /branches/bleeding_edge/src/factory.h Thu Sep 22 04:30:04 2011
+++ /branches/bleeding_edge/src/factory.h Fri Sep 23 01:00:06 2011
@@ -444,6 +444,11 @@
JSRegExp::Flags flags,
int capture_count);
+ // Returns the value for a known global constant (a property of the
global
+ // object which is neither configurable nor writable) like 'undefined'.
+ // Returns a null handle when the given name is unknown.
+ Handle<Object> GlobalConstantFor(Handle<String> name);
+
private:
Isolate* isolate() { return reinterpret_cast<Isolate*>(this); }
=======================================
--- /branches/bleeding_edge/src/heap.cc Thu Sep 22 10:10:40 2011
+++ /branches/bleeding_edge/src/heap.cc Fri Sep 23 01:00:06 2011
@@ -2192,6 +2192,11 @@
}
set_nan_value(obj);
+ { MaybeObject* maybe_obj = AllocateHeapNumber(V8_INFINITY, TENURED);
+ if (!maybe_obj->ToObject(&obj)) return false;
+ }
+ set_infinity_value(obj);
+
{ MaybeObject* maybe_obj = Allocate(oddball_map(), OLD_POINTER_SPACE);
if (!maybe_obj->ToObject(&obj)) return false;
}
=======================================
--- /branches/bleeding_edge/src/heap.h Thu Sep 22 06:54:53 2011
+++ /branches/bleeding_edge/src/heap.h Fri Sep 23 01:00:06 2011
@@ -126,6 +126,7 @@
V(Map, message_object_map,
JSMessageObjectMap) \
V(Map, foreign_map,
ForeignMap) \
V(Object, nan_value,
NanValue) \
+ V(Object, infinity_value,
InfinityValue) \
V(Object, minus_zero_value,
MinusZeroValue) \
V(Map, neander_map,
NeanderMap) \
V(JSObject, message_listeners,
MessageListeners) \
@@ -229,7 +230,9 @@
V(closure_symbol, "(closure)") \
V(use_strict, "use strict") \
V(dot_symbol, ".") \
- V(anonymous_function_symbol, "(anonymous function)")
+ V(anonymous_function_symbol, "(anonymous function)") \
+ V(infinity_symbol, "Infinity") \
+ V(minus_infinity_symbol, "-Infinity")
// Forward declarations.
class GCTracer;
=======================================
--- /branches/bleeding_edge/src/hydrogen.cc Thu Sep 22 04:30:04 2011
+++ /branches/bleeding_edge/src/hydrogen.cc Fri Sep 23 01:00:06 2011
@@ -3146,6 +3146,16 @@
}
switch (variable->location()) {
case Variable::UNALLOCATED: {
+ // Handle known global constants like 'undefined' specially to avoid
a
+ // load from a global cell for them.
+ Handle<Object> constant_value =
+ isolate()->factory()->GlobalConstantFor(variable->name());
+ if (!constant_value.is_null()) {
+ HConstant* instr =
+ new(zone()) HConstant(constant_value,
Representation::Tagged());
+ return ast_context()->ReturnInstruction(instr, expr->id());
+ }
+
LookupResult lookup;
GlobalPropertyAccess type =
LookupGlobalProperty(variable, &lookup, false);
=======================================
--- /branches/bleeding_edge/src/runtime.cc Thu Sep 22 10:12:41 2011
+++ /branches/bleeding_edge/src/runtime.cc Fri Sep 23 01:00:06 2011
@@ -3938,13 +3938,13 @@
// Slow case.
CONVERT_DOUBLE_ARG_CHECKED(value, 0);
if (isnan(value)) {
- return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+ return *isolate->factory()->nan_symbol();
}
if (isinf(value)) {
if (value < 0) {
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
- }
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+ return *isolate->factory()->minus_infinity_symbol();
+ }
+ return *isolate->factory()->infinity_symbol();
}
char* str = DoubleToRadixCString(value, radix);
MaybeObject* result =
@@ -3960,13 +3960,13 @@
CONVERT_DOUBLE_ARG_CHECKED(value, 0);
if (isnan(value)) {
- return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+ return *isolate->factory()->nan_symbol();
}
if (isinf(value)) {
if (value < 0) {
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
- }
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+ return *isolate->factory()->minus_infinity_symbol();
+ }
+ return *isolate->factory()->infinity_symbol();
}
CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
int f = FastD2I(f_number);
@@ -3985,13 +3985,13 @@
CONVERT_DOUBLE_ARG_CHECKED(value, 0);
if (isnan(value)) {
- return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+ return *isolate->factory()->nan_symbol();
}
if (isinf(value)) {
if (value < 0) {
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
- }
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+ return *isolate->factory()->minus_infinity_symbol();
+ }
+ return *isolate->factory()->infinity_symbol();
}
CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
int f = FastD2I(f_number);
@@ -4010,13 +4010,13 @@
CONVERT_DOUBLE_ARG_CHECKED(value, 0);
if (isnan(value)) {
- return isolate->heap()->AllocateStringFromAscii(CStrVector("NaN"));
+ return *isolate->factory()->nan_symbol();
}
if (isinf(value)) {
if (value < 0) {
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("-Infinity"));
- }
- return
isolate->heap()->AllocateStringFromAscii(CStrVector("Infinity"));
+ return *isolate->factory()->minus_infinity_symbol();
+ }
+ return *isolate->factory()->infinity_symbol();
}
CONVERT_DOUBLE_ARG_CHECKED(f_number, 1);
int f = FastD2I(f_number);
--
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