Fix constants bound to redeclared function args

The changes in #2476 ensured that function inputs like `input x;`
retained their single-bit size when instantiated with a constant
argument and turned into a localparam. That change did not handle the
possibility for an input to be redeclared later on with an explicit
width, such as `integer x;`.

2 files changed, 26 insertions, 5 deletions

diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 5fa4ac83b..c6d63f247 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -3344,11 +3344,22 @@ skip_dynamic_range_lvalue_expansion:;
 						wire->children.insert(wire->children.begin(), arg->clone());
 						// args without a range implicitly have width 1
 						if (wire->children.back()->type != AST_RANGE) {
-							AstNode* range = new AstNode();
-							range->type = AST_RANGE;
-							wire->children.push_back(range);
-							range->children.push_back(mkconst_int(0, true));
-							range->children.push_back(mkconst_int(0, true));
+							// check if this wire is redeclared with an explicit size
+							bool uses_explicit_size = false;
+							for (const AstNode *other_child : decl->children)
+								if (other_child->type == AST_WIRE && child->str == other_child->str
+										&& !other_child->children.empty()
+										&& other_child->children.back()->type == AST_RANGE) {
+									uses_explicit_size = true;
+									break;
+								}
+							if (!uses_explicit_size) {
+								AstNode* range = new AstNode();
+								range->type = AST_RANGE;
+								wire->children.push_back(range);
+								range->children.push_back(mkconst_int(0, true));
+								range->children.push_back(mkconst_int(0, true));
+							}
 						}
 						continue;
 					}
diff --git a/tests/various/const_arg_loop.v b/tests/various/const_arg_loop.v
index ed15aa135..358fb439a 100644
--- a/tests/various/const_arg_loop.v
+++ b/tests/various/const_arg_loop.v
@@ -50,6 +50,12 @@ module top;
 		operation4 = {a, b};
 	endfunction
 
+	function automatic integer operation5;
+		input x;
+		integer x;
+		operation5 = x;
+	endfunction
+
 	wire [31:0] a;
 	assign a = 2;
 
@@ -70,6 +76,9 @@ module top;
 	wire [16:0] x4;
 	assign x4 = operation4(a[15:0], 0);
 
+	wire [31:0] x5;
+	assign x5 = operation5(64);
+
 // `define VERIFY
 `ifdef VERIFY
     assert property (a == 2);
@@ -79,5 +88,6 @@ module top;
     assert property (x2 == 4);
     assert property (x3 == 16);
     assert property (x4 == a << 1);
+    assert property (x5 == 64);
 `endif
 endmodule