Changeset 145491 in webkit

Timestamp:

Mar 12, 2013 12:02:51 AM (11 years ago)

Author:

fpizlo@apple.com

Message:

DFG prediction propagation phase should not rerun forward propagation if double voting has already converged
​https://bugs.webkit.org/show_bug.cgi?id=111920

Reviewed by Oliver Hunt.

I don't know why we weren't exiting early after double voting if !m_changed.

This change also removes backwards propagation from the voting fixpoint, since at that
point short-circuiting loops is probably not particularly profitable. Profiling shows
that this reduces the time spent in prediction propagation even further.

This change appears to be a 1% SunSpider speed-up.

• dfg/DFGPredictionPropagationPhase.cpp:

(JSC::DFG::PredictionPropagationPhase::run):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• dfg/DFGPredictionPropagationPhase.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2013-03-12  Filip Pizlo  <fpizlo@apple.com>
+
+        DFG prediction propagation phase should not rerun forward propagation if double voting has already converged
+        https://bugs.webkit.org/show_bug.cgi?id=111920
+
+        Reviewed by Oliver Hunt.
+        
+        I don't know why we weren't exiting early after double voting if !m_changed.
+        
+        This change also removes backwards propagation from the voting fixpoint, since at that
+        point short-circuiting loops is probably not particularly profitable. Profiling shows
+        that this reduces the time spent in prediction propagation even further.
+        
+        This change appears to be a 1% SunSpider speed-up.
+
+        * dfg/DFGPredictionPropagationPhase.cpp:
+        (JSC::DFG::PredictionPropagationPhase::run):
+
 2013-03-11  Filip Pizlo  <fpizlo@apple.com>
 

trunk/Source/JavaScriptCore/dfg/DFGPredictionPropagationPhase.cpp

@@ -74 +74 @@
             m_changed = false;
             doRoundOfDoubleVoting();
-            propagateForward();
             if (!m_changed)
                 break;
-            
             m_changed = false;
-            doRoundOfDoubleVoting();
-            propagateBackward();
+            propagateForward();
         } while (m_changed);