From 2770ddf071e5a9e8611462947fed7b02d6cbcf7a Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Thu, 15 Dec 2022 07:38:53 -0500
Subject: [PATCH] Optimize expansion of extend operators.

---
 src/V3Expand.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/V3Expand.cpp b/src/V3Expand.cpp
index 5efbb7592..86091a572 100644
--- a/src/V3Expand.cpp
+++ b/src/V3Expand.cpp
@@ -341,6 +341,18 @@ private:
             VL_DO_DANGLING(replaceWithDelete(nodep, newp), nodep);
         }
     }
+    bool expandWide(AstNodeAssign* nodep, AstExtend* rhsp) {
+        UINFO(8, "    Wordize ASSIGN(EXTEND) " << nodep << endl);
+        if (!doExpand(nodep)) return false;
+        AstNodeExpr* const lhsp = nodep->lhsp();
+        for (int w = 0; w < lhsp->widthWords(); ++w) {
+            addWordAssign(nodep, w, newAstWordSelClone(lhsp, w));
+        }
+        for (int w = rhsp->widthWords(); w < nodep->widthWords(); ++w) {
+            addWordAssign(nodep, w, new AstConst{nodep->fileline(), AstConst::SizedEData{}, 0});
+        }
+        return true;
+    }
 
     void visit(AstSel* nodep) override {
         if (nodep->user1SetOnce()) return;  // Process once
@@ -854,6 +866,8 @@ private:
                 did = expandWide(nodep, rhsp);
             } else if (AstConcat* const rhsp = VN_CAST(nodep->rhsp(), Concat)) {
                 did = expandWide(nodep, rhsp);
+            } else if (AstExtend* const rhsp = VN_CAST(nodep->rhsp(), Extend)) {
+                did = expandWide(nodep, rhsp);
             } else if (AstReplicate* const rhsp = VN_CAST(nodep->rhsp(), Replicate)) {
                 did = expandWide(nodep, rhsp);
             } else if (AstAnd* const rhsp = VN_CAST(nodep->rhsp(), And)) {