Changeset 231154 in webkit

Timestamp:

Apr 29, 2018 4:41:55 PM (6 years ago)

Author:

fpizlo@apple.com

Message:

B3 should run tail duplication at the bitter end
​https://bugs.webkit.org/show_bug.cgi?id=185123

Reviewed by Geoffrey Garen.

Also added an option to disable taildup. This appears to be a 1% AsmBench speed-up. It's neutral
everywhere else.

The goal of this change is to allow us to run path specialization after switch lowering but
before tail duplication.

• b3/B3Generate.cpp:

(JSC::B3::generateToAir):

• runtime/Options.h:

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• b3/B3Generate.cpp (modified) (3 diffs)
• runtime/Options.h (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2018-04-29  Filip Pizlo  <fpizlo@apple.com>
+
+        B3 should run tail duplication at the bitter end
+        https://bugs.webkit.org/show_bug.cgi?id=185123
+
+        Reviewed by Geoffrey Garen.
+        
+        Also added an option to disable taildup. This appears to be a 1% AsmBench speed-up. It's neutral
+        everywhere else.
+        
+        The goal of this change is to allow us to run path specialization after switch lowering but
+        before tail duplication.
+
+        * b3/B3Generate.cpp:
+        (JSC::B3::generateToAir):
+        * runtime/Options.h:
+
 2018-04-29  Commit Queue  <commit-queue@webkit.org>
 

trunk/Source/JavaScriptCore/b3/B3Generate.cpp

@@ -81 +81 @@
     if (shouldValidateIR())
         validate(procedure);
-
+    
     if (procedure.optLevel() >= 2) {
         reduceDoubleToFloat(procedure);
@@ -88 +88 @@
         if (eliminateCommonSubexpressions(procedure))
             eliminateCommonSubexpressions(procedure);
-        foldPathConstants(procedure);
-        reduceStrength(procedure);
         inferSwitches(procedure);
-        duplicateTails(procedure);
-        fixSSA(procedure);
-        foldPathConstants(procedure);
         
         // FIXME: Add more optimizations here.
@@ -106 +101 @@
 
     if (procedure.optLevel() >= 2) {
+        reduceStrength(procedure);
+        if (Options::useB3TailDup())
+            duplicateTails(procedure);
+        fixSSA(procedure);
+        foldPathConstants(procedure);
         reduceStrength(procedure);
 

trunk/Source/JavaScriptCore/runtime/Options.h

@@ -438 +438 @@
     v(bool, coalesceSpillSlots, true, Normal, nullptr) \
     v(bool, logAirRegisterPressure, false, Normal, nullptr) \
+    v(bool, useB3TailDup, true, Normal, nullptr) \
     v(unsigned, maxB3TailDupBlockSize, 3, Normal, nullptr) \
     v(unsigned, maxB3TailDupBlockSuccessors, 3, Normal, nullptr) \