Fix bug where shuffled array assignments were incorrectly collapsed i…

…n generated SV (#504)
intel · Aug 7, 2024 · 9910774 · 9910774
1 parent d41029e
commit 9910774
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Showing 2 changed files with 53 additions and 3 deletions.
diff --git a/lib/src/synthesizers/systemverilog.dart b/lib/src/synthesizers/systemverilog.dart
@@ -1218,8 +1218,8 @@ class _SynthModuleDefinition {
           final srcArray = src.parentArray;
           final dstArray = dst.parentArray;
 
-          assert(srcArray.logics.length == 1, 'should be 1');
-          assert(dstArray.logics.length == 1, 'should be 1');
+          assert(srcArray.logics.length == 1, 'should be 1 name for the array');
+          assert(dstArray.logics.length == 1, 'should be 1 name for the array');
 
           if (srcArray.logics.first.elements.length !=
                   dstArray.logics.first.elements.length ||
@@ -1236,7 +1236,31 @@ class _SynthModuleDefinition {
 
       for (final MapEntry(key: (srcArray, dstArray), value: arrAssignments)
           in groupedAssignments.entries) {
-        if (arrAssignments.length == srcArray.logics.first.elements.length) {
+        assert(
+            srcArray.logics.first.elements.length ==
+                dstArray.logics.first.elements.length,
+            'should be equal lengths of elements in both arrays by now');
+
+        // first requirement is that all elements have been assigned
+        var shouldMerge =
+            arrAssignments.length == srcArray.logics.first.elements.length;
+
+        if (shouldMerge) {
+          // only check each element if the lengths match
+          for (final arrAssignment in arrAssignments) {
+            final arrAssignmentSrc =
+                (arrAssignment.src as _SynthLogicArrayElement).logic;
+            final arrAssignmentDst =
+                (arrAssignment.dst as _SynthLogicArrayElement).logic;
+
+            if (arrAssignmentSrc.arrayIndex! != arrAssignmentDst.arrayIndex!) {
+              shouldMerge = false;
+              break;
+            }
+          }
+        }
+
+        if (shouldMerge) {
           reducedAssignments.add(_SynthAssignment(srcArray, dstArray));
         } else {
           reducedAssignments.addAll(arrAssignments);

diff --git a/test/array_collapsing_test.dart b/test/array_collapsing_test.dart
@@ -22,6 +22,17 @@ class ArrayModule extends Module {
   }
 }
 
+class ArrayWithShuffledAssignment extends Module {
+  ArrayWithShuffledAssignment(LogicArray a) {
+    final inpA = addInputArray('a', a, dimensions: a.dimensions);
+    final outB = addOutputArray('b', dimensions: a.dimensions);
+
+    for (var i = 0; i < a.dimensions.first; i++) {
+      outB.elements[i] <= inpA.elements[a.dimensions.first - i - 1];
+    }
+  }
+}
+
 class ArrayModuleWithNetIntermediates extends Module {
   ArrayModuleWithNetIntermediates(LogicArray a, LogicArray b) {
     a = addInOutArray('a', a,
@@ -69,6 +80,21 @@ void main() {
     SimCompare.checkIverilogVector(mod, vectors);
   });
 
+  test('array assignment non-collapsing with shuffled assignment', () async {
+    final mod = ArrayWithShuffledAssignment(LogicArray([4], 1));
+    await mod.build();
+
+    final sv = mod.generateSynth();
+    expect(sv, contains('assign b[0] = a[3];'));
+    expect(sv, contains('assign b[3] = a[0];'));
+
+    final vectors = [
+      Vector({'a': LogicValue.of('01xz')}, {'b': LogicValue.of('zx10')}),
+    ];
+    await SimCompare.checkFunctionalVector(mod, vectors);
+    SimCompare.checkIverilogVector(mod, vectors);
+  });
+
   test('array nets with intermediate collapse with unpacked', () async {
     final mod = ArrayModuleWithNetIntermediates(
         LogicArray([3, 3], 1, numUnpackedDimensions: 2),