Changeset 213876 in webkit

Timestamp:

Mar 13, 2017 3:52:41 PM (7 years ago)

Author:

fpizlo@apple.com

Message:

FTL should not flush strict arguments unless it really needs to
​https://bugs.webkit.org/show_bug.cgi?id=169519

Reviewed by Mark Lam.

This is a refinement that we should have done ages ago. This kills some pointless PutStacks
in DFG SSA IR. It can sometimes unlock other optimizations.

Relanding after I fixed the special cases for CreateArguments-style nodes.

• dfg/DFGPreciseLocalClobberize.h:

(JSC::DFG::PreciseLocalClobberizeAdaptor::readTop):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• dfg/DFGPreciseLocalClobberize.h (modified) (5 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2017-03-13  Filip Pizlo  <fpizlo@apple.com>
+
+        FTL should not flush strict arguments unless it really needs to
+        https://bugs.webkit.org/show_bug.cgi?id=169519
+
+        Reviewed by Mark Lam.
+        
+        This is a refinement that we should have done ages ago. This kills some pointless PutStacks
+        in DFG SSA IR. It can sometimes unlock other optimizations.
+        
+        Relanding after I fixed the special cases for CreateArguments-style nodes. 
+
+        * dfg/DFGPreciseLocalClobberize.h:
+        (JSC::DFG::PreciseLocalClobberizeAdaptor::readTop):
+
 2017-03-13  Devin Rousso  <webkit@devinrousso.com>
 

trunk/Source/JavaScriptCore/dfg/DFGPreciseLocalClobberize.h

@@ -1 +1 @@
 /*
- * Copyright (C) 2014-2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2014-2017 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -138 +138 @@
         };
 
-        bool isForwardingNode = false;
         switch (m_node->op()) {
         case ForwardVarargs:
@@ -145 +144 @@
         case TailCallForwardVarargs:
         case TailCallForwardVarargsInlinedCaller:
-            isForwardingNode = true;
-            FALLTHROUGH;
         case GetMyArgumentByVal:
-        case GetMyArgumentByValOutOfBounds: {
-
+        case GetMyArgumentByValOutOfBounds:
+        case CreateDirectArguments:
+        case CreateScopedArguments:
+        case CreateClonedArguments:
+        case PhantomDirectArguments:
+        case PhantomClonedArguments:
+        case GetRestLength:
+        case CreateRest: {
+            bool isForwardingNode = false;
+            bool isPhantomNode = false;
+            switch (m_node->op()) {
+            case ForwardVarargs:
+            case CallForwardVarargs:
+            case ConstructForwardVarargs:
+            case TailCallForwardVarargs:
+            case TailCallForwardVarargsInlinedCaller:
+                isForwardingNode = true;
+                break;
+            case PhantomDirectArguments:
+            case PhantomClonedArguments:
+                isPhantomNode = true;
+                break;
+            default:
+                break;
+            }
+            
+            if (isPhantomNode && isFTL(m_graph.m_plan.mode))
+                break;
+            
             if (isForwardingNode && m_node->hasArgumentsChild() && m_node->argumentsChild() && m_node->argumentsChild()->op() == PhantomNewArrayWithSpread) {
                 Node* arrayWithSpread = m_node->argumentsChild().node();
@@ -195 +219 @@
             break;
         }
-
             
         default: {
-            // All of the outermost arguments, except this, are definitely read.
-            for (unsigned i = m_graph.m_codeBlock->numParameters(); i-- > 1;)
-                m_read(virtualRegisterForArgument(i));
+            // All of the outermost arguments, except this, are read in sloppy mode.
+            if (!m_graph.m_codeBlock->isStrictMode()) {
+                for (unsigned i = m_graph.m_codeBlock->numParameters(); i-- > 1;)
+                    m_read(virtualRegisterForArgument(i));
+            }
         
             // The stack header is read.
@@ -208 +233 @@
             // Read all of the inline arguments and call frame headers that we didn't already capture.
             for (InlineCallFrame* inlineCallFrame = m_node->origin.semantic.inlineCallFrame; inlineCallFrame; inlineCallFrame = inlineCallFrame->getCallerInlineFrameSkippingTailCalls()) {
-                for (unsigned i = inlineCallFrame->arguments.size(); i-- > 1;)
-                    m_read(VirtualRegister(inlineCallFrame->stackOffset + virtualRegisterForArgument(i).offset()));
+                if (!inlineCallFrame->isStrictMode()) {
+                    for (unsigned i = inlineCallFrame->arguments.size(); i-- > 1;)
+                        m_read(VirtualRegister(inlineCallFrame->stackOffset + virtualRegisterForArgument(i).offset()));
+                }
                 if (inlineCallFrame->isClosureCall)
                     m_read(VirtualRegister(inlineCallFrame->stackOffset + CallFrameSlot::callee));