Revision: 10817
Author: [email protected]
Date: Fri Feb 24 00:46:10 2012
Log: Speed up removing phi nodes.
BUG=
TEST=
Review URL: https://chromiumcodereview.appspot.com/9452022
http://code.google.com/p/v8/source/detail?r=10817
Modified:
/branches/bleeding_edge/src/hydrogen-instructions.cc
/branches/bleeding_edge/src/hydrogen-instructions.h
/branches/bleeding_edge/src/hydrogen.cc
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.cc Thu Feb 23
07:37:27 2012
+++ /branches/bleeding_edge/src/hydrogen-instructions.cc Fri Feb 24
00:46:10 2012
@@ -383,19 +383,7 @@
// We replace all uses first, so Delete can assert that there are none.
if (other != NULL) ReplaceAllUsesWith(other);
ASSERT(HasNoUses());
- // Clearing the operands includes going through the use list of each
operand
- // to remove this HValue, which can be expensive. Instead, we mark this
as
- // dead and only check the first item in the use list of each operand.
- // For the following items in the use lists we rely on the tail() method
to
- // skip dead dead items and remove them lazily.
- SetFlag(kIsDead);
- for (int i = 0; i < OperandCount(); ++i) {
- HValue* operand = OperandAt(i);
- HUseListNode* first = operand->use_list_;
- if (first != NULL && first->index() == i && first->value() == this) {
- operand->use_list_ = first->tail();
- }
- }
+ Kill();
DeleteFromGraph();
}
@@ -413,9 +401,17 @@
}
-void HValue::ClearOperands() {
+void HValue::Kill() {
+ // Instead of going through the entire use list of each operand, we only
+ // check the first item in each use list and rely on the tail() method to
+ // skip dead items, removing them lazily next time we traverse the list.
+ SetFlag(kIsDead);
for (int i = 0; i < OperandCount(); ++i) {
- SetOperandAt(i, NULL);
+ HValue* operand = OperandAt(i);
+ HUseListNode* first = operand->use_list_;
+ if (first != NULL && first->value() == this && first->index() == i) {
+ operand->use_list_ = first->tail();
+ }
}
}
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.h Thu Feb 23 05:59:35
2012
+++ /branches/bleeding_edge/src/hydrogen-instructions.h Fri Feb 24 00:46:10
2012
@@ -631,7 +631,9 @@
return use_list_ != NULL && use_list_->tail() != NULL;
}
int UseCount() const;
- void ClearOperands();
+
+ // Mark this HValue as dead and to be removed from other HValues' use
lists.
+ void Kill();
int flags() const { return flags_; }
void SetFlag(Flag f) { flags_ |= (1 << f); }
=======================================
--- /branches/bleeding_edge/src/hydrogen.cc Wed Feb 22 08:45:35 2012
+++ /branches/bleeding_edge/src/hydrogen.cc Fri Feb 24 00:46:10 2012
@@ -97,7 +97,7 @@
ASSERT(phi->block() == this);
ASSERT(phis_.Contains(phi));
ASSERT(phi->HasNoUses() || !phi->is_live());
- phi->ClearOperands();
+ phi->Kill();
phis_.RemoveElement(phi);
phi->SetBlock(NULL);
}
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