Changeset 117706 in webkit for trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp

Timestamp:

May 20, 2012, 3:00:08 AM (13 years ago)

Author:

[email protected]

Message:

Bytecompiler should emit trivially fewer jumps in loops
​https://bugs.webkit.org/show_bug.cgi?id=85144

Reviewed by Oliver Hunt.

Merged r115587 from dfgopt.

1-2% across the board win.

• bytecompiler/NodesCodegen.cpp:

(JSC::WhileNode::emitBytecode):
(JSC::ForNode::emitBytecode):

File:

• trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp (modified) (3 diffs)

trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp

@@ -1545 +1545 @@
 {
     RefPtr<LabelScope> scope = generator.newLabelScope(LabelScope::Loop);
-
-    generator.emitJump(scope->continueTarget());
-
     RefPtr<Label> topOfLoop = generator.newLabel();
+
+    generator.emitDebugHook(WillExecuteStatement, m_expr->lineNo(), m_expr->lineNo());
+    if (m_expr->hasConditionContextCodegen())
+        generator.emitNodeInConditionContext(m_expr, topOfLoop.get(), scope->breakTarget(), true);
+    else {
+        RegisterID* cond = generator.emitNode(m_expr);
+        generator.emitJumpIfFalse(cond, scope->breakTarget());
+    }
+
     generator.emitLabel(topOfLoop.get());
     generator.emitLoopHint();
@@ -1580 +1586 @@
     if (m_expr1)
         generator.emitNode(generator.ignoredResult(), m_expr1);
-
-    RefPtr<Label> condition = generator.newLabel();
-    generator.emitJump(condition.get());
-
+    
     RefPtr<Label> topOfLoop = generator.newLabel();
+    if (m_expr2) {
+        if (m_expr2->hasConditionContextCodegen())
+            generator.emitNodeInConditionContext(m_expr2, topOfLoop.get(), scope->breakTarget(), true);
+        else {
+            RegisterID* cond = generator.emitNode(m_expr2);
+            generator.emitJumpIfFalse(cond, scope->breakTarget());
+        }
+    }
+
     generator.emitLabel(topOfLoop.get());
     generator.emitLoopHint();
@@ -1595 +1607 @@
         generator.emitNode(generator.ignoredResult(), m_expr3);
 
-    generator.emitLabel(condition.get());
     if (m_expr2) {
         if (m_expr2->hasConditionContextCodegen())