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Allow loading constant function from proto chain.

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This enables Crankshaft to use HConstant for loading constant functions
on the prototype chain when building a monomorphic load. This pattern
appears in several JavaScript frameworks.

R=svenpanne@chromium.org
TEST=mjsunit/compiler/proto-chain-constant

Review URL: https://codereview.chromium.org/12052008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13463 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
mstarzinger@chromium.org 2013-01-22 12:03:35 +00:00
parent 90d0f18007
commit f8d5260af7
2 changed files with 67 additions and 1 deletions
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13
src/hydrogen.cc
View File

@ -6290,7 +6290,7 @@ HInstruction* HOptimizedGraphBuilder::BuildLoadNamedMonomorphic(
return new(zone()) HConstant(function, Representation::Tagged());
}
// Handle a load from a known field somewhere in the protoype chain.
// Handle a load from a known field somewhere in the prototype chain.
LookupInPrototypes(map, name, &lookup);
if (lookup.IsField()) {
Handle<JSObject> prototype(JSObject::cast(map->prototype()));
@ -6302,6 +6302,17 @@ HInstruction* HOptimizedGraphBuilder::BuildLoadNamedMonomorphic(
return BuildLoadNamedField(holder_value, holder_map, &lookup);
}
// Handle a load of a constant function somewhere in the prototype chain.
if (lookup.IsConstantFunction()) {
Handle<JSObject> prototype(JSObject::cast(map->prototype()));
Handle<JSObject> holder(lookup.holder());
Handle<Map> holder_map(holder->map());
AddCheckMapsWithTransitions(object, map);
AddInstruction(new(zone()) HCheckPrototypeMaps(prototype, holder, zone()));
Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*holder_map));
return new(zone()) HConstant(function, Representation::Tagged());
}
// No luck, do a generic load.
return BuildLoadNamedGeneric(object, name, expr);
}

55
test/mjsunit/compiler/proto-chain-constant.js Normal file
View File

@ -0,0 +1,55 @@
// Copyright 2013 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Flags: --allow-natives-syntax
// Test loading a constant function on the prototype chain.
var c = Object.create;
var obj4 = c(null, { f4: { value: function() { return 4; }, writable: true }});
var obj3 = c(obj4, { f3: { value: function() { return 3; }, writable: true }});
var obj2 = c(obj3, { f2: { value: function() { return 2; }, writable: true }});
var obj1 = c(obj2, { f1: { value: function() { return 1; }, writable: true }});
var obj0 = c(obj1, { f0: { value: function() { return 0; }, writable: true }});
function get4(obj) { return obj.f4; }
assertEquals(4, get4(obj0)());
assertEquals(4, get4(obj0)());
%OptimizeFunctionOnNextCall(get4);
assertEquals(4, get4(obj0)());
obj4.f4 = function() { return 5; };
assertEquals(5, get4(obj0)());
function get3(obj) { return obj.f3; }
assertEquals(3, get3(obj0)());
assertEquals(3, get3(obj0)());
%OptimizeFunctionOnNextCall(get3);
assertEquals(3, get3(obj0)());
obj2.f3 = function() { return 6; };
assertEquals(6, get3(obj0)());