Merge pull request #1185 from paulp/210-updateConserve

Eliminated a metric ton of allocations.

2 files changed, 36 insertions, 27 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
index 8bbf11650c..486a43614b 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/BasicBlocks.scala
@@ -42,10 +42,14 @@ trait BasicBlocks {
 
     private final class SuccessorList() {
       private var successors: List[BasicBlock] = Nil
+      /** This method is very hot! Handle with care. */
       private def updateConserve() {
-        var lb: ListBuffer[BasicBlock] = null
-        var matches = 0
-        var remaining = successors
+        var lb: ListBuffer[BasicBlock]              = null
+        var matches                                 = 0
+        var remaining                               = successors
+        val direct                                  = directSuccessors
+        var scratchHandlers: List[ExceptionHandler] = method.exh
+        var scratchBlocks: List[BasicBlock]         = direct
 
         def addBlock(bb: BasicBlock) {
           if (matches < 0)
@@ -60,25 +64,27 @@ trait BasicBlocks {
           }
         }
 
-        // exceptionSuccessors
-        method.exh foreach { handler =>
-          if (handler covers outer)
-            addBlock(handler.startBlock)
+        while (scratchBlocks ne Nil) {
+          addBlock(scratchBlocks.head)
+          scratchBlocks = scratchBlocks.tail
         }
-        // directSuccessors
-        val direct = directSuccessors
-        direct foreach addBlock
-
         /** Return a list of successors for 'b' that come from exception handlers
          *  covering b's (non-exceptional) successors. These exception handlers
          *  might not cover 'b' itself. This situation corresponds to an
          *  exception being thrown as the first thing of one of b's successors.
          */
-        method.exh foreach { handler =>
-          direct foreach { block =>
-            if (handler covers block)
+        while (scratchHandlers ne Nil) {
+          val handler = scratchHandlers.head
+          if (handler covers outer)
+            addBlock(handler.startBlock)
+
+          scratchBlocks = direct
+          while (scratchBlocks ne Nil) {
+            if (handler covers scratchBlocks.head)
               addBlock(handler.startBlock)
+            scratchBlocks = scratchBlocks.tail
           }
+          scratchHandlers = scratchHandlers.tail
         }
         // Blocks did not align: create a new list.
         if (matches < 0)
@@ -101,7 +107,7 @@ trait BasicBlocks {
     }
 
     /** Flags of this basic block. */
-    private var flags: Int = 0
+    private[this] var flags: Int = 0
 
     /** Does this block have the given flag? */
     def hasFlag(flag: Int): Boolean = (flags & flag) != 0
diff --git a/test/files/run/inline-ex-handlers.check b/test/files/run/inline-ex-handlers.check
index a4c9f215e8..2bc72893e7 100644
--- a/test/files/run/inline-ex-handlers.check
+++ b/test/files/run/inline-ex-handlers.check
@@ -61,22 +61,22 @@
 >     ?	LOAD_LOCAL(variable monitor4)
 >     305	MONITOR_EXIT
 >     ?	JUMP 12
-550c557,563
+550c557
 <     ?	THROW(Throwable)
 ---
 >     ?	JUMP 12
+556c563,570
+<     ?	THROW(Throwable)
+---
+>     ?	STORE_LOCAL(value t)
+>     ?	JUMP 13
 >     
 >   12: 
 >     ?	LOAD_LOCAL(variable monitor3)
 >     304	MONITOR_EXIT
 >     ?	STORE_LOCAL(value t)
 >     ?	JUMP 13
-556c569,582
-<     ?	THROW(Throwable)
----
->     ?	STORE_LOCAL(value t)
->     ?	JUMP 13
->     
+571a586,597
 >   13: 
 >     310	LOAD_MODULE object Predef
 >     310	CALL_PRIMITIVE(StartConcat)
@@ -88,6 +88,7 @@
 >     310	CALL_PRIMITIVE(EndConcat)
 >     310	CALL_METHOD scala.Predef.println (dynamic)
 >     310	JUMP 2
+>     
 580c606
 <     catch (Throwable) in ArrayBuffer(7, 8, 9, 10) starting at: 6
 ---
@@ -110,12 +111,12 @@
 >     81	LOAD_LOCAL(value e)
 >     ?	STORE_LOCAL(variable exc1)
 >     ?	JUMP 12
-668c700,714
+668c700,701
 <     81	THROW(Exception)
 ---
 >     ?	STORE_LOCAL(variable exc1)
 >     ?	JUMP 12
->     
+684a718,730
 >   12: 
 >     83	LOAD_MODULE object Predef
 >     83	CONSTANT("finally")
@@ -128,6 +129,7 @@
 >     84	STORE_LOCAL(variable result)
 >     84	LOAD_LOCAL(variable exc1)
 >     84	THROW(Throwable)
+>     
 690c736
 <     catch (<none>) in ArrayBuffer(4, 6, 7, 9) starting at: 3
 ---
@@ -171,17 +173,18 @@
 ---
 >     ?	STORE_LOCAL(value ex6)
 >     ?	JUMP 33
-802c854,861
+802c854,855
 <     170	THROW(Throwable)
 ---
 >     ?	STORE_LOCAL(value ex6)
 >     ?	JUMP 33
->     
+811a865,870
 >   33: 
 >     169	LOAD_LOCAL(value ex6)
 >     169	STORE_LOCAL(value x4)
 >     169	SCOPE_ENTER value x4
 >     169	JUMP 5
+>     
 826,829d884
 <     180	LOAD_LOCAL(value x5)
 <     180	CALL_METHOD MyException.message (dynamic)
@@ -207,7 +210,7 @@
 ---
 >     ?	STORE_LOCAL(variable exc2)
 >     ?	JUMP 34
-842a902,914
+857a917,929
 >   34: 
 >     184	LOAD_MODULE object Predef
 >     184	CONSTANT("finally")