Fix little endian interface pin swizzling (#2475).

Changes

@@ -7,6 +7,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Support concat selection (#2721).
 
+****  Fix little endian interface pin swizzling (#2475). [Don Owen]
+
 ****  Fix TIMESCALE warnings on primitives (#2763). [Xuanqi]
 
 ****  Fix $fread extra semicolon inside statements. [Leendert van Doorn]

src/V3Inst.cpp

@@ -396,7 +396,8 @@ private:
             AstNode* prevPinp = nullptr;
             // Clone the var referenced by the pin, and clone each var referenced by the varref
             // Clone pin varp:
-            for (int i = pinArrp->lo(); i <= pinArrp->hi(); ++i) {
+            for (int in = 0; in < pinArrp->elementsConst(); ++in) {
+                int i = pinArrp->left() + in * pinArrp->declRange().leftToRightInc();
                 string varNewName = pinVarp->name() + "__BRA__" + cvtToStr(i) + "__KET__";
                 AstVar* varNewp = nullptr;
 
@@ -429,16 +430,20 @@ private:
                 newp->modVarp(varNewp);
                 newp->name(newp->name() + "__BRA__" + cvtToStr(i) + "__KET__");
                 // And replace exprp with a new varxref
-                int offset = 0;
                 const AstVarRef* varrefp = VN_CAST(newp->exprp(), VarRef);
+                int offset = 0;
                 if (varrefp) {
                 } else if (AstSliceSel* slicep = VN_CAST(newp->exprp(), SliceSel)) {
                     varrefp = VN_CAST(slicep->fromp(), VarRef);
                     UASSERT(VN_IS(slicep->rhsp(), Const), "Slices should be constant");
                     offset = VN_CAST(slicep->rhsp(), Const)->toSInt();
                 }
-                if (!varrefp) { newp->exprp()->v3error("Unexpected connection to arrayed port"); }
+                int expr_i = i;
-                string newname = varrefp->name() + "__BRA__" + cvtToStr(i + offset) + "__KET__";
+                if (auto* exprArrp = VN_CAST(newp->exprp()->dtypep(), UnpackArrayDType))
+                    expr_i = exprArrp->left()
+                             + (in + offset) * exprArrp->declRange().leftToRightInc();
+                if (!varrefp) newp->exprp()->v3error("Unexpected connection to arrayed port");
+                string newname = varrefp->name() + "__BRA__" + cvtToStr(expr_i) + "__KET__";
                 AstVarXRef* newVarXRefp
                     = new AstVarXRef(nodep->fileline(), newname, "", VAccess::WRITE);
                 newVarXRefp->varp(newp->modVarp());

test_regress/t/t_mod_interface_array4.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_mod_interface_array4.v

@@ -0,0 +1,78 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2021 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+`define stop $stop
+`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got='h%x exp='h%x\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0)
+
+interface intf ();
+   integer index;
+endinterface
+
+module sub
+  (
+   input logic clk,
+   input int cyc,
+   intf alh[1:2],
+   intf ahl[2:1],
+   intf blh[1:2],
+   intf bhl[2:1]
+   );
+
+   always @(posedge clk) begin
+      if (cyc == 5) begin
+         `checkh(alh[1].index, 2);
+         `checkh(alh[2].index, 1);
+         `checkh(ahl[1].index, 1);
+         `checkh(ahl[2].index, 2);
+         `checkh(blh[1].index, 1);
+         `checkh(blh[2].index, 2);
+         `checkh(bhl[1].index, 2);
+         `checkh(bhl[2].index, 1);
+         $write("*-* All Finished *-*\n");
+         $finish;
+      end
+   end
+
+endmodule
+
+module t
+  (
+   clk
+   );
+   input clk;
+
+   intf ifa1_intf[2:1]();
+   intf ifa2_intf[2:1]();
+   intf ifb1_intf[1:2]();
+   intf ifb2_intf[1:2]();
+
+   int   cyc;
+
+   sub sub
+      (
+       .clk,
+       .cyc,
+       .alh(ifa1_intf),
+       .ahl(ifa2_intf),
+       .blh(ifb1_intf),
+       .bhl(ifb2_intf)
+       );
+
+   always @(posedge clk) begin
+      cyc <= cyc + 1;
+      if (cyc == 1) begin
+         ifa1_intf[1].index = 1;
+         ifa1_intf[2].index = 2;
+         ifa2_intf[1].index = 1;
+         ifa2_intf[2].index = 2;
+         ifb1_intf[1].index = 1;
+         ifb1_intf[2].index = 2;
+         ifb2_intf[1].index = 1;
+         ifb2_intf[2].index = 2;
+      end
+   end
+
+endmodule