Changeset 278424 in webkit

Timestamp:

Jun 3, 2021 3:27:32 PM (3 years ago)

Author:

fpizlo@apple.com

Message:

DFG should eliminate obvious store barriers
​https://bugs.webkit.org/show_bug.cgi?id=226604

Reviewed by Mark Lam.

This has a couple changes:

• PutByOffset doesn't GC! So let's not say that it does.

• The store barrier clustering phase is no longer called the store barrier fencing phase in dumps.

Small Speedometer2 speed-up. Definite speed-up for Elm.

• dfg/DFGDoesGC.cpp:

(JSC::DFG::doesGC):

• dfg/DFGStoreBarrierClusteringPhase.cpp:

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• dfg/DFGDoesGC.cpp (modified) (3 diffs)
• dfg/DFGStoreBarrierClusteringPhase.cpp (modified) (3 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2021-06-03  Filip Pizlo  <fpizlo@apple.com>
+
+        DFG should eliminate obvious store barriers
+        https://bugs.webkit.org/show_bug.cgi?id=226604
+
+        Reviewed by Mark Lam.
+
+        This has a couple changes:
+        
+        - PutByOffset doesn't GC! So let's not say that it does.
+
+        - The store barrier clustering phase is no longer called the store barrier fencing phase in
+          dumps.
+
+        Small Speedometer2 speed-up. Definite speed-up for Elm.
+
+        * dfg/DFGDoesGC.cpp:
+        (JSC::DFG::doesGC):
+        * dfg/DFGStoreBarrierClusteringPhase.cpp:
+
 2021-06-03  Patrick Angle  <pangle@apple.com>
 

trunk/Source/JavaScriptCore/dfg/DFGDoesGC.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2014-2020 Apple Inc. All rights reserved.
+ * Copyright (C) 2014-2021 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -259 +259 @@
     case DataViewGetFloat:
     case DataViewSet:
+    case PutByOffset:
         return false;
 
@@ -321 +322 @@
     case PutByIdFlush:
     case PutByIdWithThis:
-    case PutByOffset:
     case PutByValWithThis:
     case PutDynamicVar:

trunk/Source/JavaScriptCore/dfg/DFGStoreBarrierClusteringPhase.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2016 Apple Inc. All rights reserved.
+ * Copyright (C) 2016-2021 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -41 +41 @@
 namespace {
 
+constexpr bool verbose = false;
+
 class StoreBarrierClusteringPhase : public Phase {
 public:
     StoreBarrierClusteringPhase(Graph& graph)
-        : Phase(graph, "store barrier fencing")
+        : Phase(graph, "store barrier clustering")
         , m_insertionSet(graph)
     {
@@ -99 +101 @@
             // don't have evidence that it would be worth it.
             if (doesGC(m_graph, node) || mayExit(m_graph, node) != DoesNotExit) {
+                if (verbose) {
+                    dataLog("Possible GC point at ", node, "\n");
+                    dataLog("    doesGC = ", doesGC(m_graph, node), "\n");
+                    dataLog("    mayExit = ", mayExit(m_graph, node), "\n");
+                }
                 futureGC = true;
                 continue;