Remove SOM block restart primitive and use recursion to explain #whil…

…eTrue:

The #whileTrue: code is never actually executed, and the block primitive has not been used ever since TruffleSOM.

Remove it as a cleanup. ‘Explaining’ the behavior of #whileTrue: with recursion is much nicer. The implementation relies on a node substitution/lowering anyway. So, stack overflow isn’t an issue.

Signed-off-by: Stefan Marr <git@stefan-marr.de>

core-lib/Kernel.som

@@ -592,9 +592,9 @@ class Kernel vmMirror: vmMirror = Object <: Value (
     )
 
     public whileTrue: block = (
-      self value ifFalse: [ ^ nil ].
+      value ifFalse: [ ^ nil ].
       block value.
-      self restart
+      ^ whileTrue: block
     )
 
     (* Exception support *)
@@ -605,12 +605,6 @@ class Kernel vmMirror: vmMirror = Object <: Value (
     public ensure: aBlock = (
       ^ vmMirror exceptionDo: self ensure: aBlock
     )
-
-    (* TODO: this feels still like old legacy, it's not how it works...
-             on the other hand, seeing the #whileTrue: semantics is useful.
-             so, replacing it directly with a primitive call isn't nice either *)
-    (* Restarting *)
-    public restart = ( ^ vmMirror blockRestart: self )
   )
 
   protected class Block1 = Block ()()

src/som/primitives/BlockPrims.java

@@ -19,7 +19,6 @@
 import som.interpreter.nodes.nary.TernaryExpressionNode;
 import som.interpreter.nodes.nary.UnaryExpressionNode;
 import som.vm.VmSettings;
-import som.vmobjects.SAbstractObject;
 import som.vmobjects.SBlock;
 import som.vmobjects.SInvokable;
 import tools.dym.Tags.OpClosureApplication;
@@ -48,21 +47,6 @@ public static final IndirectCallNode create() {
     return Truffle.getRuntime().createIndirectCallNode();
   }
 
-  @GenerateNodeFactory
-  @Primitive(primitive = "blockRestart:")
-  public abstract static class RestartPrim extends UnaryExpressionNode {
-    public RestartPrim(final boolean eagWrap, final SourceSection source) { super(eagWrap, source); }
-
-    @Specialization
-    public SAbstractObject doSBlock(final SBlock receiver) {
-      CompilerDirectives.transferToInterpreter();
-      // TruffleSOM intrinsifies #whileTrue: and #whileFalse:
-      throw new RuntimeException("This primitive is not supported anymore! "
-          + "Something went wrong with the intrinsification of "
-          + "#whileTrue:/#whileFalse:?");
-    }
-  }
-
   @GenerateNodeFactory
   @ImportStatic(BlockPrims.class)
   @Primitive(primitive = "blockValue:", selector = "value", inParser = false,