frontend: Optimize assembly definition expansion

Author: flofriday

vadl/main/vadl/ast/MacroExpander.java

@@ -215,7 +215,7 @@ public List<AssemblyDefinition> expandAssemblies(AssemblyDefinition definition)
       result.add(new AssemblyDefinition(
           new ArrayList<>(List.of(identifier)),
           expandExpr(definition.expr),
-          copyLoc(definition.loc)
+          definition.loc
       ));
     }
     return result;

vadl/main/vadl/ast/Parser.frame

@@ -32,6 +32,7 @@ import vadl.utils.VirtualFileSystem;
 import vadl.error.Diagnostic;
 import static vadl.error.Diagnostic.error;
 
+@SuppressWarnings("NonApiType") // We know what we are doing, the implementation matters sometimes.
 public class Parser {
 
   /**

vadl/main/vadl/ast/ParserUtils.java

@@ -25,12 +25,12 @@
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
-import java.util.stream.Stream;
 import javax.annotation.Nullable;
 import vadl.error.Diagnostic;
 import vadl.error.DiagnosticList;
@@ -681,21 +681,25 @@ static Node expandNode(Parser parser, Node node) {
    * Assembly definitions can be written with multiple identifiers to be bound to multiple
    * (pseudo) instructions. However, for correct further processing they need to be expanded into
    * multiple definitions.
+   * The input requires a linked list because otherwise performance would degredate.
    *
    * @param isaDefs to be expanded.
    * @return returns the original isaDefs with the Assemblies expanded.
    */
-  static List<Definition> expandAssemblyDefinitionsInIsa(List<Definition> isaDefs) {
-    // FIXME: We could modify the list inplace here for performance
-    return isaDefs.stream()
-        .flatMap(def -> {
-          if (def instanceof AssemblyDefinition assembly) {
-            return new MacroExpander(Map.of(), Map.of(), def.location().fullExpandedFromStack())
-                .expandAssemblies(assembly).stream();
-          }
-          return Stream.of(def);
-        })
-        .collect(Collectors.toCollection(ArrayList::new));
+  static LinkedList<Definition> expandAssemblyDefinitionsInIsa(LinkedList<Definition> isaDefs) {
+    for (var iter = isaDefs.listIterator(); iter.hasNext(); ) {
+      var def = iter.next();
+      if (!(def instanceof AssemblyDefinition assembly) || assembly.identifiers.size() == 1) {
+        continue;
+      }
+
+      var expanded = new MacroExpander(Map.of(), Map.of(), def.location().fullExpandedFromStack())
+          .expandAssemblies(assembly);
+      iter.set(expanded.getFirst());
+      expanded.subList(1, expanded.size()).forEach(iter::add);
+    }
+
+    return isaDefs;
   }
 
   /**

vadl/main/vadl/ast/vadl.ATG

@@ -20,6 +20,7 @@ import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.HashMap;
 import java.util.List;
+import java.util.LinkedList;
 import java.util.Map;
 import java.util.Objects;
 import javax.annotation.Nullable;
@@ -440,12 +441,12 @@ The #commonDefinitionList production rule lists (beside macro definitions) all c
                                                                           readMacroSymbols(macroTable, extendingIsa);
                                                                     }); .)
     SYM_EQ SYM_BRACE_OPEN
-    isaDefinitionList<.out List<Definition> definitions.>       (. macroTable = macroTable.pop(); .)
+    isaDefinitionList<.out LinkedList<Definition> definitions.>       (. macroTable = macroTable.pop(); .)
     SYM_BRACE_CLOSE                                             (. isaDef = new InstructionSetDefinition(identifier, extending, ParserUtils.expandAssemblyDefinitionsInIsa(definitions), startLocation.join(lastTokenLoc()));
                                                                    macroTable.defineSymbol(isaDef); .)
   .
 
-  isaDefinitionList<.out List<Definition> definitions.> (. definitions = new ArrayList<>(); .)
+  isaDefinitionList<.out LinkedList<Definition> definitions.> (. definitions = new LinkedList<>(); .)
   = {
     annotations<.out List<AnnotationDefinition> annotations.>
     isaDefinition<out Definition def>                   (. def.withAnnotations(annotations); definitions.add(def); .)