From 28187823eda1c49470ed50177f1cc97aa944b3f7 Mon Sep 17 00:00:00 2001
From: Paul Rigge <rigge@google.com>
Date: Thu, 11 Apr 2024 15:56:20 -0700
Subject: [PATCH] Update handling of single-element arrays.

Also, add a test. This fixes #1113.
---
 ivtest/ivltests/single_element_array.v     | 31 ++++++++++++++++++++++
 ivtest/regress-vvp.list                    |  1 +
 ivtest/vvp_tests/single_element_array.json |  4 +++
 tgt-vvp/vvp_scope.c                        |  8 +++---
 4 files changed, 40 insertions(+), 4 deletions(-)
 create mode 100644 ivtest/ivltests/single_element_array.v
 create mode 100644 ivtest/vvp_tests/single_element_array.json

diff --git a/ivtest/ivltests/single_element_array.v b/ivtest/ivltests/single_element_array.v
new file mode 100644
index 0000000000..18f91175d6
--- /dev/null
+++ b/ivtest/ivltests/single_element_array.v
@@ -0,0 +1,31 @@
+module SingleElementArray(
+  input wire [48:0] x1,
+  output wire [48:0] out
+);
+  wire [48:0] x17[0:0];
+  assign x17[0] = x1;
+  assign out = {x17[0]};
+endmodule
+
+module testbench;
+  reg [48:0] in;
+  wire [48:0] out;
+
+  SingleElementArray dut(.x1(in), .out(out));
+
+  initial begin
+    in = 49'h0000000000000;
+    #1;
+    if (out != 49'h0000000000000) begin
+      $display("FAILED");
+      $finish;
+    end
+    in = 49'h1555555555555;
+    #1;
+    if (out != 49'h1555555555555) begin
+      $display("FAILED");
+      $finish;
+    end
+    $display("PASSED");
+  end
+endmodule
diff --git a/ivtest/regress-vvp.list b/ivtest/regress-vvp.list
index 1e67e16b98..cb56e7b661 100644
--- a/ivtest/regress-vvp.list
+++ b/ivtest/regress-vvp.list
@@ -173,6 +173,7 @@ sf_countones_fail		vvp_tests/sf_countones_fail.json
 sf_isunknown_fail		vvp_tests/sf_isunknown_fail.json
 sf_onehot_fail			vvp_tests/sf_onehot_fail.json
 sf_onehot0_fail			vvp_tests/sf_onehot0_fail.json
+single_element_array 		vvp_tests/single_element_array.json
 struct_enum_partsel		vvp_tests/struct_enum_partsel.json
 struct_field_left_right		vvp_tests/struct_field_left_right.json
 struct_nested1			vvp_tests/struct_nested1.json
diff --git a/ivtest/vvp_tests/single_element_array.json b/ivtest/vvp_tests/single_element_array.json
new file mode 100644
index 0000000000..cfc255c36a
--- /dev/null
+++ b/ivtest/vvp_tests/single_element_array.json
@@ -0,0 +1,4 @@
+{
+    "type"   : "normal",
+    "source" : "single_element_array.v"
+}
diff --git a/tgt-vvp/vvp_scope.c b/tgt-vvp/vvp_scope.c
index c4a6599581..978b27d59f 100644
--- a/tgt-vvp/vvp_scope.c
+++ b/tgt-vvp/vvp_scope.c
@@ -689,7 +689,6 @@ static void draw_net_in_scope(ivl_signal_t sig)
 		  nex_data->net_word = iword;
 
 	    } else if (dimensions > 0) {
-
 		    /* In this case, we have an alias to an existing
 		       signal array. this typically is an instance of
 		       port collapsing that the elaborator combined to
@@ -697,13 +696,14 @@ static void draw_net_in_scope(ivl_signal_t sig)
 		       so the word count for the signal and the alias
 		       *must* match. */
 
-		  if (word_count == ivl_signal_array_count(nex_data->net)) {
-		    if (iword == 0) {
+		  if (ivl_signal_dimensions(nex_data->net) > 0 &&
+                      word_count == ivl_signal_array_count(nex_data->net)) {
+                    if (iword == 0) {
 		      fprintf(vvp_out, "v%p .array \"%s\", v%p; Alias to %s \n",
 			      sig, vvp_mangle_name(ivl_signal_basename(sig)),
 			      nex_data->net,
 			      ivl_signal_basename(nex_data->net));
-		    }
+                    }
 		    /* An alias for an individual word. */
 		  } else {
 			if (iword == 0) {