Auto-extend and WIDTH warn on unsized X/Zs, bug1423.

Changes

@@ -14,6 +14,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Add error when use parameters without value, bug1424. [Peter Gerst]
 
+****  Auto-extend and WIDTH warn on unsized X/Zs, bug1423. [Udi Finkelstein]
+
 ****  Fix missing VL_SHIFTL_ errors, bug1412, bug1415. [Larry Lee]
 
 ****  Fix MinGW GCC 6 printf formats, bug1413. [Sergey Kvachonok]

src/V3Number.cpp

@@ -1656,8 +1656,20 @@ V3Number& V3Number::opAssign(const V3Number& lhs) {
 V3Number& V3Number::opExtendS(const V3Number& lhs, uint32_t lbits) {
     // Note may be a width change during the sign extension
     setZero();
-    for(int bit=0; bit<this->width(); bit++) {
+    for (int bit=0; bit < width(); bit++) {
-	setBit(bit,lhs.bitIsExtend(bit, lbits));
+        char extendWith = lhs.bitIsExtend(bit, lbits);
+        setBit(bit, extendWith);
+    }
+    return *this;
+}
+
+V3Number& V3Number::opExtendXZ(const V3Number& lhs, uint32_t lbits) {
+    // Note may be a width change during the X/Z extension
+    setZero();
+    for (int bit=0; bit < width(); bit++) {
+        char extendWith = lhs.bitIsExtend(bit, lbits);
+        if (extendWith == '1' || extendWith == 1) extendWith = 0;
+        setBit(bit, lhs.bitIsExtend(bit, lbits));
     }
     return *this;
 }

src/V3Number.h

@@ -199,6 +199,7 @@ public:
     bool isLtXZ(const V3Number& rhs) const;  // operator< with XZ compared
     void isSigned(bool ssigned) { m_signed=ssigned; }
     bool isUnknown() const;
+    bool isMsbXZ() const { return bitIsXZ(m_width); }
     uint32_t toUInt() const;
     vlsint32_t toSInt() const;
     vluint64_t toUQuad() const;
@@ -233,6 +234,7 @@ public:
     //
     V3Number& opAssign  (const V3Number& lhs);
     V3Number& opExtendS (const V3Number& lhs, uint32_t lbits);  // Sign extension
+    V3Number& opExtendXZ(const V3Number& lhs, uint32_t lbits);  // X/Z extension
     V3Number& opRedOr 	(const V3Number& lhs);
     V3Number& opRedAnd	(const V3Number& lhs);
     V3Number& opRedXor	(const V3Number& lhs);

src/V3Width.cpp

@@ -3170,6 +3170,24 @@ private:
 		nodepr = newp;
 		return true;
 	    }
+            // X/Z also upper bit extend.  In pre-SV only to 32-bits, SV forever.
+            else if (!constp->num().sized()
+                     // Make it the proper size.  Careful of proper extension of 0's/1's
+                     && expWidth > 32 && constp->num().isMsbXZ()) {
+                constp->v3warn(WIDTH, "Unsized constant being X/Z extended to "
+                               <<expWidth<<" bits: "<<constp->prettyName());
+                V3Number num (constp->fileline(), expWidth);
+                num.opExtendXZ(constp->num(), constp->width());
+                AstNode* newp = new AstConst(constp->fileline(), num);
+                // Spec says always unsigned with proper width
+                if (debug()>4) constp->dumpTree(cout,"  fixUnszExtend_old: ");
+                if (debug()>4)   newp->dumpTree(cout,"               _new: ");
+                constp->replaceWith(newp);
+                constp->deleteTree(); VL_DANGLING(constp);
+                // Tell caller the new constp, and that we changed it.
+                nodepr = newp;
+                return true;
+            }
         }
         return false;  // No change
     }

test_regress/t/t_const.v

@@ -3,16 +3,16 @@
 // This file ONLY is placed into the Public Domain, for any use,
 // without warranty, 2019 by Wilson Snyder.
 
-module t (/*AUTOARG*/);
+module t(/*AUTOARG*/);
 
    initial begin
       // verilator lint_off WIDTH
       if (32'hxxxxxxxx !== 'hx) $stop;
       if (32'hzzzzzzzz !== 'hz) $stop;
       if (32'h???????? !== 'h?) $stop;
-      if (32'hxxxxxxxx !== 'dx) $stop;
+      if (68'hx_xxxxxxxx_xxxxxxxx !== 'dX) $stop;
-      if (32'hzzzzzzzz !== 'dz) $stop;
+      if (68'hz_zzzzzzzz_zzzzzzzz !== 'dZ) $stop;
-      if (32'h???????? !== 'd?) $stop;
+      if (68'h?_????????_???????? !== 'd?) $stop;
       // verilator lint_on WIDTH
       $write("*-* All Finished *-*\n");
       $finish;

test_regress/t/t_const_bad.out

@@ -0,0 +1,5 @@
+%Warning-WIDTH: t/t_const_bad.v:12: Unsized constant being X/Z extended to 68 bits: ?32?bxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+%Warning-WIDTH: Use "/* verilator lint_off WIDTH */" and lint_on around source to disable this message.
+%Warning-WIDTH: t/t_const_bad.v:13: Unsized constant being X/Z extended to 68 bits: ?32?bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
+%Warning-WIDTH: t/t_const_bad.v:14: Unsized constant being X/Z extended to 68 bits: ?32?bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
+%Error: Exiting due to

test_regress/t/t_const_bad.pl

@@ -0,0 +1,22 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2004 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.
+
+scenarios(vlt => 1);
+
+compile(
+    v_flags2 => ["--lint-only"],
+    verilator_make_gcc => 0,
+    make_top_shell => 0,
+    make_main => 0,
+    fails => 1,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_const_bad.v

@@ -0,0 +1,19 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2019 by Wilson Snyder.
+
+module t(/*AUTOARG*/);
+
+   initial begin
+      if (32'hxxxxxxxx !== 'hx) $stop;
+      if (32'hzzzzzzzz !== 'hz) $stop;
+      if (32'h???????? !== 'h?) $stop;
+      if (68'hx_xxxxxxxx_xxxxxxxx !== 'dX) $stop;
+      if (68'hz_zzzzzzzz_zzzzzzzz !== 'dZ) $stop;
+      if (68'h?_????????_???????? !== 'd?) $stop;
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+endmodule