Changeset 179756 in webkit for trunk/Source/JavaScriptCore/dfg/DFGCPSRethreadingPhase.cpp

Timestamp:

Feb 6, 2015, 1:39:04 PM (10 years ago)

Author:

[email protected]

Message:

It should be possible to use the DFG SetArgument node to indicate that someone set the value of a local out-of-band
​https://bugs.webkit.org/show_bug.cgi?id=141337

Reviewed by Mark Lam.

This mainly involved ensuring that SetArgument behaves just like SetLocal from a CPS standpoint, but with a special case for those SetArguments that
are associated with the prologue.

• dfg/DFGCPSRethreadingPhase.cpp:

(JSC::DFG::CPSRethreadingPhase::run):
(JSC::DFG::CPSRethreadingPhase::canonicalizeSet):
(JSC::DFG::CPSRethreadingPhase::canonicalizeLocalsInBlock):
(JSC::DFG::CPSRethreadingPhase::specialCaseArguments):
(JSC::DFG::CPSRethreadingPhase::canonicalizeSetLocal): Deleted.
(JSC::DFG::CPSRethreadingPhase::canonicalizeSetArgument): Deleted.

File:

• trunk/Source/JavaScriptCore/dfg/DFGCPSRethreadingPhase.cpp (modified) (6 diffs)

trunk/Source/JavaScriptCore/dfg/DFGCPSRethreadingPhase.cpp

@@ -55 +55 @@
         m_graph.clearReplacements();
         canonicalizeLocalsInBlocks();
+        specialCaseArguments();
         propagatePhis<LocalOperand>();
         propagatePhis<ArgumentOperand>();
@@ -234 +235 @@
     }
     
-    void canonicalizeSetLocal(Node* node)
-    {
-        m_block->variablesAtTail.setOperand(node->local(), node);
-    }
-    
     template<NodeType nodeType, OperandKind operandKind>
     void canonicalizeFlushOrPhantomLocalFor(Node* node, VariableAccessData* variable, size_t idx)
@@ -299 +295 @@
     }
     
-    void canonicalizeSetArgument(Node* node)
-    {
-        VirtualRegister local = node->local();
-        ASSERT(local.isArgument());
-        int argument = local.toArgument();
-        m_block->variablesAtHead.setArgumentFirstTime(argument, node);
-        m_block->variablesAtTail.setArgumentFirstTime(argument, node);
+    void canonicalizeSet(Node* node)
+    {
+        m_block->variablesAtTail.setOperand(node->local(), node);
     }
     
@@ -370 +362 @@
                 
             case SetLocal:
-                canonicalizeSetLocal(node);
+                canonicalizeSet(node);
                 break;
                 
@@ -382 +374 @@
                 
             case SetArgument:
-                canonicalizeSetArgument(node);
+                canonicalizeSet(node);
                 break;
                 
@@ -403 +395 @@
             canonicalizeLocalsInBlock();
         }
+    }
+    
+    void specialCaseArguments()
+    {
+        // Normally, a SetArgument denotes the start of a live range for a local's value on the stack.
+        // But those SetArguments used for the actual arguments to the machine CodeBlock get
+        // special-cased. We could have instead used two different node types - one for the arguments
+        // at the prologue case, and another for the other uses. But this seemed like IR overkill.
+        for (unsigned i = m_graph.m_arguments.size(); i--;)
+            m_graph.block(0)->variablesAtHead.setArgumentFirstTime(i, m_graph.m_arguments[i]);
     }