Fix nested generate if genblk naming (#3189).

Changes

@@ -16,6 +16,7 @@ Verilator 4.215 devel
 * Internal code cleanups and improvements. [Geza Lore]
 * Fix array method names with parens (#3181) (#3183). [Teng Huang]
 * Fix split_var assign merging (#3177) (#3179). [Yutetsu TAKATSUKASA]
+* Fix nested generate if genblk naming (#3189). [yanx21]
 
 
 Verilator 4.214 2021-10-17

src/V3LinkParse.cpp

@@ -105,6 +105,21 @@ private:
         }
     }
 
+    bool nestedIfBegin(AstBegin* nodep) {  // Point at begin inside the GenIf
+        // IEEE says directly nested item is not a new block
+        // The genblk name will get attached to the if true/false LOWER begin block(s)
+        //    1: GENIF
+        // -> 1:3: BEGIN [GEN] [IMPLIED]  // nodep passed to this function
+        //    1:3:1: GENIF
+        //    1:3:1:2: BEGIN genblk1 [GEN] [IMPLIED]
+        AstNode* const backp = nodep->backp();
+        return (nodep->implied()  // User didn't provide begin/end
+                && VN_IS(backp, GenIf) && VN_CAST(backp, GenIf)->elsesp() == nodep
+                && !nodep->nextp()  // No other statements under upper genif else
+                && (VN_IS(nodep->stmtsp(), GenIf))  // Begin has if underneath
+                && !nodep->stmtsp()->nextp());  // Has only one item
+    }
+
     // VISITs
     virtual void visit(AstNodeFTask* nodep) override {
         if (!nodep->user1SetOnce()) {  // Process only once.
@@ -539,12 +554,10 @@ private:
     virtual void visit(AstBegin* nodep) override {
         V3Config::applyCoverageBlock(m_modp, nodep);
         cleanFileline(nodep);
-        AstNode* backp = nodep->backp();
+        AstNode* const backp = nodep->backp();
         // IEEE says directly nested item is not a new block
-        const bool nestedIf = (nodep->implied()  // User didn't provide begin/end
-                               && (VN_IS(nodep->stmtsp(), GenIf)
-                                   || VN_IS(nodep->stmtsp(), GenCase))  // Has an if/case
-                               && !nodep->stmtsp()->nextp());  // Has only one item
+        // The genblk name will get attached to the if true/false LOWER begin block(s)
+        const bool nestedIf = nestedIfBegin(nodep);
         // It's not FOR(BEGIN(...)) but we earlier changed it to BEGIN(FOR(...))
         if (nodep->genforp()) {
             ++m_genblkNum;
@@ -576,9 +589,13 @@ private:
         }
     }
     virtual void visit(AstGenIf* nodep) override {
-        ++m_genblkNum;
         cleanFileline(nodep);
-        {
+        bool nestedIf
+            = (VN_IS(nodep->backp(), Begin) && nestedIfBegin(VN_CAST(nodep->backp(), Begin)));
+        if (nestedIf) {
+            iterateChildren(nodep);
+        } else {
+            ++m_genblkNum;
             VL_RESTORER(m_genblkAbove);
             VL_RESTORER(m_genblkNum);
             m_genblkAbove = m_genblkNum;

test_regress/t/t_gen_ifelse.pl

@@ -0,0 +1,21 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2021 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+scenarios(simulator => 1);
+
+compile(
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;

test_regress/t/t_gen_ifelse.v

@@ -0,0 +1,35 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2021 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module s;
+   parameter A = 0;
+   generate
+      if (A == 1)
+            int i;
+      else if (A == 2)
+                 int i;
+      else
+           int i;
+   endgenerate
+   generate
+      if (A == 1)
+            int i;
+      else if (A == 2)
+                 int i;
+      else
+           int i;
+   endgenerate
+endmodule
+
+module t;
+   s #(0) s0();
+   s #(1) s1();
+   s #(2) s2();
+   initial begin
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule