Author: [email protected]
Date: Wed Mar 18 03:37:37 2009
New Revision: 1529
Modified:
branches/bleeding_edge/src/virtual-frame-ia32.cc
branches/bleeding_edge/src/virtual-frame.cc
branches/bleeding_edge/src/virtual-frame.h
Log:
Add a bit to a virtual frame element telling if it's been copied. Set
it when a copy is made, clear it when the element is next written.
Review URL: http://codereview.chromium.org/42324
Modified: branches/bleeding_edge/src/virtual-frame-ia32.cc
==============================================================================
--- branches/bleeding_edge/src/virtual-frame-ia32.cc (original)
+++ branches/bleeding_edge/src/virtual-frame-ia32.cc Wed Mar 18 03:37:37
2009
@@ -550,6 +550,7 @@
return copy;
}
+ elements_[index].clear_copied();
return FrameElement::InvalidElement();
}
@@ -569,7 +570,9 @@
// push that register on top of the frame. If it is copied,
// make the first copy the backing store and push a fresh copy
// on top of the frame.
- FrameElement copy = AdjustCopies(index);
+ FrameElement copy = original.is_copied()
+ ? AdjustCopies(index)
+ : FrameElement::InvalidElement();
if (copy.is_valid()) {
// The original element was a copy. Push the copy of the new
// backing store.
@@ -593,7 +596,9 @@
// If the element is not copied, push it on top of the frame.
// If it is copied, make the first copy be the new backing store
// and push a fresh copy on top of the frame.
- FrameElement copy = AdjustCopies(index);
+ FrameElement copy = original.is_copied()
+ ? AdjustCopies(index)
+ : FrameElement::InvalidElement();
if (copy.is_valid()) {
// The original element was a copy. Push the copy of the new
// backing store.
@@ -634,7 +639,8 @@
FrameElement original = elements_[index];
// If the stored-to slot may be copied, adjust to preserve the
// copy-on-write semantics of copied elements.
- if (original.is_register() || original.is_memory()) {
+ if (original.is_copied() &&
+ (original.is_register() || original.is_memory())) {
FrameElement ignored = AdjustCopies(index);
}
Modified: branches/bleeding_edge/src/virtual-frame.cc
==============================================================================
--- branches/bleeding_edge/src/virtual-frame.cc (original)
+++ branches/bleeding_edge/src/virtual-frame.cc Wed Mar 18 03:37:37 2009
@@ -93,9 +93,11 @@
case FrameElement::REGISTER:
// All copies are backed by memory or register locations.
result.type_ =
- FrameElement::TypeField::encode(FrameElement::COPY) |
- FrameElement::SyncField::encode(FrameElement::NOT_SYNCED);
+ FrameElement::TypeField::encode(FrameElement::COPY)
+ | FrameElement::IsCopiedField::encode(false)
+ | FrameElement::SyncField::encode(FrameElement::NOT_SYNCED);
result.data_.index_ = index;
+ elements_[index].set_copied();
break;
case FrameElement::INVALID:
@@ -367,7 +369,8 @@
// If the original may be a copy, adjust to preserve the copy-on-write
// semantics of copied elements.
- if (original.is_register() || original.is_memory()) {
+ if (original.is_copied() &&
+ (original.is_register() || original.is_memory())) {
FrameElement ignored = AdjustCopies(frame_index);
}
Modified: branches/bleeding_edge/src/virtual-frame.h
==============================================================================
--- branches/bleeding_edge/src/virtual-frame.h (original)
+++ branches/bleeding_edge/src/virtual-frame.h Wed Mar 18 03:37:37 2009
@@ -101,6 +101,16 @@
bool is_constant() const { return type() == CONSTANT; }
bool is_copy() const { return type() == COPY; }
+ bool is_copied() const { return IsCopiedField::decode(type_); }
+
+ void set_copied() {
+ type_ = (type_ & ~IsCopiedField::mask()) | IsCopiedField::encode(true);
+ }
+
+ void clear_copied() {
+ type_ = (type_ & ~IsCopiedField::mask()) |
IsCopiedField::encode(false);
+ }
+
Register reg() const {
ASSERT(is_register());
return data_.reg_;
@@ -129,7 +139,8 @@
// BitField is <type, shift, size>.
class SyncField : public BitField<SyncFlag, 0, 1> {};
- class TypeField : public BitField<Type, 1, 32 - 1> {};
+ class IsCopiedField : public BitField<bool, 1, 1> {};
+ class TypeField : public BitField<Type, 2, 32 - 2> {};
Type type() const { return TypeField::decode(type_); }
@@ -144,10 +155,6 @@
int index_;
} data_;
- // The index of the next element in a list of copies, or the frame's
- // illegal index if there is no next element.
- int next_;
-
// Used to construct memory and register elements.
FrameElement(Type type, Register reg, SyncFlag is_synced) {
Initialize(type, reg, is_synced);
@@ -175,16 +182,18 @@
namespace v8 { namespace internal {
FrameElement::FrameElement(Handle<Object> value, SyncFlag is_synced) {
- type_ = TypeField::encode(CONSTANT) | SyncField::encode(is_synced);
+ type_ = TypeField::encode(CONSTANT)
+ | IsCopiedField::encode(false)
+ | SyncField::encode(is_synced);
data_.handle_ = value.location();
- next_ = VirtualFrame::kIllegalIndex;
}
void FrameElement::Initialize(Type type, Register reg, SyncFlag is_synced)
{
- type_ = TypeField::encode(type) | SyncField::encode(is_synced);
+ type_ = TypeField::encode(type)
+ | IsCopiedField::encode(false)
+ | SyncField::encode(is_synced);
data_.reg_ = reg;
- next_ = VirtualFrame::kIllegalIndex;
}
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