fixed a merging issue

src/main/java/de/neemann/digital/hdl/model2/HDLCircuit.java

@@ -524,7 +524,7 @@ public class HDLCircuit implements Iterable<HDLNode>, HDLModel.BitProvider, Prin
      */
     public HDLCircuit applyDefaultOptimizations() throws HDLException {
         apply(new ReplaceOneToMany());
-        apply(new MergeAssignements());
+        apply(new MergeAssignments());
         apply(new InlineManyToOne());
         apply(new RemoveConstantSignals());
         apply(new MergeConstants());  // under certain circumstances there are still constants

src/main/java/de/neemann/digital/hdl/model2/expression/Expression.java

@@ -14,7 +14,7 @@ import de.neemann.digital.hdl.model2.Printable;
 public interface Expression extends Printable {
 
     /**
-     * Replaces a net with and expression
+     * Replaces a net with an expression
      *
      * @param net        the net to replace
      * @param expression the expression to use instead ot the net
@@ -31,7 +31,7 @@ public interface Expression extends Printable {
     }
 
     /**
-     * Help er to check if a expression is a net reference
+     * Helper to check if an expression is a net reference
      *
      * @param expr the expression to check
      * @param net  the net

src/main/java/de/neemann/digital/hdl/model2/optimizations/MergeAssignments.java

@@ -6,14 +6,16 @@
 package de.neemann.digital.hdl.model2.optimizations;
 
 import de.neemann.digital.hdl.model2.*;
+import de.neemann.digital.hdl.model2.expression.ExprVarRange;
 import de.neemann.digital.hdl.model2.expression.Expression;
+import de.neemann.digital.hdl.model2.expression.Visitor;
 
 import java.util.ArrayList;
 
 /**
  * Merges the bool expression by inlining nodes which also represent a bool expression.
  */
-public class MergeAssignements implements Optimization {
+public class MergeAssignments implements Optimization {
     private HDLCircuit circuit;
     private ArrayList<HDLNode> nodes;
 
@@ -29,14 +31,18 @@ public class MergeAssignements implements Optimization {
             for (int i = 0; i < nodes.size(); i++) {
                 HDLNode n1 = nodes.get(i);
                 if (n1 instanceof HDLNodeAssignment) {
-                    for (HDLPort p : n1.getInputs()) {
+                    HDLNodeAssignment host = (HDLNodeAssignment) n1;
+                    for (HDLPort p : host.getInputs()) {
                         HDLNode n2 = searchCreator(p.getNet());
                         if (n2 != null && n2 instanceof HDLNodeAssignment) {
-                            if (n2.getOutputs().size() == 1 && n2.getOutput().getNet().getInputs().size() == 1) {
-                                nodes.set(i, merge((HDLNodeAssignment) n1, (HDLNodeAssignment) n2));
-                                nodes.remove(n2);
-                                wasOptimization = true;
-                                break outer;
+                            HDLNodeAssignment include = (HDLNodeAssignment) n2;
+                            if (include.getOutputs().size() == 1 && include.getOutput().getNet().getInputs().size() == 1) {
+                                if (allowedToReplaceNet(host.getExpression(), include.getOutput().getNet())) {
+                                    nodes.set(i, merge(host, include));
+                                    nodes.remove(n2);
+                                    wasOptimization = true;
+                                    break outer;
+                                }
                             }
                         }
                     }
@@ -45,6 +51,12 @@ public class MergeAssignements implements Optimization {
         } while (wasOptimization);
     }
 
+    private boolean allowedToReplaceNet(Expression expression, HDLNet net) {
+        final CheckVarRangeVisitor visitor = new CheckVarRangeVisitor(net);
+        expression.traverse(visitor);
+        return visitor.ok;
+    }
+
     private HDLNodeAssignment merge(HDLNodeAssignment host, HDLNodeAssignment include) {
         final Expression expression = host.getExpression();
         final HDLNet obsoleteNet = include.getOutput().getNet();
@@ -77,4 +89,23 @@ public class MergeAssignements implements Optimization {
                     return n;
         return null;
     }
+
+    private static final class CheckVarRangeVisitor implements Visitor {
+        private final HDLNet net;
+        private boolean ok;
+
+        private CheckVarRangeVisitor(HDLNet net) {
+            this.net = net;
+            ok = true;
+        }
+
+        @Override
+        public void visit(Expression expression) {
+            if (expression instanceof ExprVarRange) {
+                ExprVarRange evr = (ExprVarRange) expression;
+                if (evr.getNet() == net)
+                    ok = false;
+            }
+        }
+    }
 }

src/test/java/de/neemann/digital/hdl/model2/HDLModelTest.java

@@ -26,7 +26,7 @@ public class HDLModelTest extends TestCase {
 
     public void testSimple() throws IOException, PinException, HDLException, NodeException, ElementNotFoundException {
         HDLCircuit hdl = getCircuit("dig/hdl/model2/comb.dig", null)
-                .apply(new MergeAssignements())
+                .apply(new MergeAssignments())
                 .apply(new NodeSorterExpressionBased())
                 .nameUnnamedSignals();
 
@@ -215,7 +215,7 @@ public class HDLModelTest extends TestCase {
 
     public void testConstantMerge() throws IOException, PinException, HDLException, NodeException, ElementNotFoundException {
         HDLCircuit hdl = getCircuit("dig/hdl/model2/constMerge.dig", null)
-                .apply(new MergeAssignements())
+                .apply(new MergeAssignments())
                 .apply(new MergeConstants())
                 .apply(new NameConstantSignals())
                 .apply(new NodeSorterExpressionBased())
@@ -292,7 +292,7 @@ public class HDLModelTest extends TestCase {
     public void testSplitter3() throws IOException, PinException, HDLException, NodeException, ElementNotFoundException {
         HDLCircuit hdl = getCircuit("dig/hdl/model2/splitter3.dig", null)
                 .apply(new ReplaceOneToMany())
-                .apply(new MergeAssignements())
+                .apply(new MergeAssignments())
                 .apply(new NodeSorterExpressionBased())
                 .nameUnnamedSignals();
 
@@ -323,7 +323,7 @@ public class HDLModelTest extends TestCase {
     public void testSplitter4() throws IOException, PinException, HDLException, NodeException, ElementNotFoundException {
         HDLCircuit hdl = getCircuit("dig/hdl/model2/splitter4.dig", null)
                 .apply(new ReplaceOneToMany())
-                .apply(new MergeAssignements())
+                .apply(new MergeAssignments())
                 .apply(new NodeSorterExpressionBased())
                 .nameUnnamedSignals();
 

src/test/java/de/neemann/digital/hdl/vhdl2/ClockTest.java

@@ -14,7 +14,6 @@ import de.neemann.digital.hdl.model2.HDLException;
 import de.neemann.digital.hdl.model2.HDLModel;
 import de.neemann.digital.hdl.model2.clock.ClockIntegratorGeneric;
 import de.neemann.digital.hdl.model2.clock.HDLClockIntegrator;
-import de.neemann.digital.hdl.model2.optimizations.MergeAssignements;
 import de.neemann.digital.hdl.printer.CodePrinter;
 import de.neemann.digital.hdl.printer.CodePrinterStr;
 import de.neemann.digital.hdl.vhdl2.boards.ClockIntegratorARTIX7;

src/test/java/de/neemann/digital/hdl/vhdl2/DescriptionTest.java

@@ -12,8 +12,6 @@ import de.neemann.digital.hdl.hgs.HGSEvalException;
 import de.neemann.digital.hdl.model2.HDLCircuit;
 import de.neemann.digital.hdl.model2.HDLException;
 import de.neemann.digital.hdl.model2.HDLModel;
-import de.neemann.digital.hdl.model2.optimizations.MergeConstants;
-import de.neemann.digital.hdl.model2.optimizations.MergeAssignements;
 import de.neemann.digital.hdl.printer.CodePrinterStr;
 import de.neemann.digital.integration.ToBreakRunner;
 import junit.framework.TestCase;

src/test/java/de/neemann/digital/hdl/vhdl2/VHDLSimulatorTest.java

@@ -59,7 +59,7 @@ public class VHDLSimulatorTest extends TestCase {
         File examples = new File(Resources.getRoot(), "/dig/hdl");
         try {
             int tested = new FileScanner(this::checkVHDLExport).noOutput().scan(examples);
-            assertEquals(45, tested);
+            assertEquals(46, tested);
         } catch (FileScanner.SkipAllException e) {
             // if ghdl is not installed its also ok
         }

src/test/resources/dig/hdl/model2/avoidVarRangeMerge.dig

@@ -0,0 +1,114 @@
+<?xml version="1.0" encoding="utf-8"?>
+<circuit>
+  <version>1</version>
+  <attributes/>
+  <visualElements>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>A</string>
+        </entry>
+        <entry>
+          <string>Bits</string>
+          <int>8</int>
+        </entry>
+      </elementAttributes>
+      <pos x="40" y="100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>In</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>B</string>
+        </entry>
+        <entry>
+          <string>Bits</string>
+          <int>8</int>
+        </entry>
+      </elementAttributes>
+      <pos x="40" y="140"/>
+    </visualElement>
+    <visualElement>
+      <elementName>And</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Bits</string>
+          <int>8</int>
+        </entry>
+      </elementAttributes>
+      <pos x="60" y="100"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Splitter</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Input Splitting</string>
+          <string>8</string>
+        </entry>
+        <entry>
+          <string>Output Splitting</string>
+          <string>4</string>
+        </entry>
+      </elementAttributes>
+      <pos x="160" y="120"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Out</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Label</string>
+          <string>Y</string>
+        </entry>
+        <entry>
+          <string>Bits</string>
+          <int>4</int>
+        </entry>
+      </elementAttributes>
+      <pos x="220" y="120"/>
+    </visualElement>
+    <visualElement>
+      <elementName>Testcase</elementName>
+      <elementAttributes>
+        <entry>
+          <string>Testdata</string>
+          <testData>
+            <dataString>A B Y
+0 0 0
+0 1 0
+1 0 0
+1 1 1
+
+0 0 0
+0 255 0
+255 0 0
+255 255 15
+</dataString>
+          </testData>
+        </entry>
+      </elementAttributes>
+      <pos x="80" y="180"/>
+    </visualElement>
+  </visualElements>
+  <wires>
+    <wire>
+      <p1 x="40" y="100"/>
+      <p2 x="60" y="100"/>
+    </wire>
+    <wire>
+      <p1 x="120" y="120"/>
+      <p2 x="160" y="120"/>
+    </wire>
+    <wire>
+      <p1 x="180" y="120"/>
+      <p2 x="220" y="120"/>
+    </wire>
+    <wire>
+      <p1 x="40" y="140"/>
+      <p2 x="60" y="140"/>
+    </wire>
+  </wires>
+  <measurementOrdering/>
+</circuit>