Support timeunit/timeprecision in $unit.

Changes

@@ -14,6 +14,7 @@ Verilator 4.211 devel
 **Minor:**
 
 * Support unpacked array localparams in tasks/functions (#3078). [Geza Lore]
+* Support timeunit/timeprecision in $unit.
 * Add --instr-count-dpi to tune assumed DPI import cost for multithreaded
   model scheduling. Default value changed to 200 (#3068). [Yinan Xu]
 * Output files are split based on the set of headers required

src/V3LinkLevel.cpp

@@ -100,10 +100,16 @@ void V3LinkLevel::timescaling(const ModVec& mods) {
     if (unit.isNone()) unit = VTimescale(VTimescale::TS_DEFAULT);
     v3Global.rootp()->timeunit(unit);
 
+    bool dunitTimed = false;  // $unit had a timeunit
+    if (const AstPackage* const upkgp = v3Global.rootp()->dollarUnitPkgp()) {
+        if (!upkgp->timeunit().isNone()) dunitTimed = true;
+    }
+
     for (AstNodeModule* nodep : mods) {
         if (!v3Global.opt.timeOverrideUnit().isNone()) nodep->timeunit(unit);
         if (nodep->timeunit().isNone()) {
             if (modTimedp  // Got previous
+                && !dunitTimed
                 && (  // unit doesn't already include an override
                     v3Global.opt.timeOverrideUnit().isNone()
                     && v3Global.opt.timeDefaultUnit().isNone())

src/V3ParseImp.cpp

@@ -108,10 +108,12 @@ void V3ParseImp::timescaleMod(FileLine* fl, AstNodeModule* modp, bool unitSet, d
         }
     }
     if (!unit.isNone()) {
+        unit = v3Global.opt.timeComputeUnit(unit);
         if (modp) {
-            modp->timeunit(v3Global.opt.timeComputeUnit(unit));
+            modp->timeunit(unit);
         } else {
-            fl->v3error("timeunit/timeprecision not under a module");
+            v3Global.rootp()->timeunit(unit);
+            unitPackage(fl)->timeunit(unit);
         }
     }
     v3Global.rootp()->timeprecisionMerge(fl, prec);

src/V3ParseImp.h

@@ -301,6 +301,18 @@ public:
 
     //==== Symbol tables
     V3ParseSym* symp() { return m_symp; }
+    AstPackage* unitPackage(FileLine* fl) {
+        // Find one made earlier?
+        VSymEnt* const rootSymp = symp()->symRootp()->findIdFlat(AstPackage::dollarUnitName());
+        AstPackage* pkgp;
+        if (!rootSymp) {
+            pkgp = parsep()->rootp()->dollarUnitPkgAddp();
+            symp()->reinsert(pkgp, symp()->symRootp());  // Don't push/pop scope as they're global
+        } else {
+            pkgp = VN_CAST(rootSymp->nodep(), Package);
+        }
+        return pkgp;
+    }
 
 public:
     // CONSTRUCTORS

src/verilog.y

@@ -148,18 +148,6 @@ public:
         m_pinNum = m_pinStack.top();
         m_pinStack.pop();
     }
-    AstPackage* unitPackage(FileLine* fl) {
-        // Find one made earlier?
-        VSymEnt* symp = SYMP->symRootp()->findIdFlat(AstPackage::dollarUnitName());
-        AstPackage* pkgp;
-        if (!symp) {
-            pkgp = PARSEP->rootp()->dollarUnitPkgAddp();
-            SYMP->reinsert(pkgp, SYMP->symRootp());  // Don't push/pop scope as they're global
-        } else {
-            pkgp = VN_CAST(symp->nodep(), Package);
-        }
-        return pkgp;
-    }
     AstNodeDType* addRange(AstBasicDType* dtypep, AstNodeRange* rangesp, bool isPacked) {
         // If dtypep isn't basic, don't use this, call createArray() instead
         if (!rangesp) {
@@ -1043,8 +1031,8 @@ description:			// ==IEEE: description
 	|	interface_declaration			{ }
 	|	program_declaration			{ }
 	|	package_declaration			{ }
-	|	package_item				{ if ($1) GRAMMARP->unitPackage($1->fileline())->addStmtp($1); }
+	|	package_item				{ if ($1) PARSEP->unitPackage($1->fileline())->addStmtp($1); }
-       	|	bind_directive				{ if ($1) GRAMMARP->unitPackage($1->fileline())->addStmtp($1); }
+       	|	bind_directive				{ if ($1) PARSEP->unitPackage($1->fileline())->addStmtp($1); }
 	//	unsupported	// IEEE: config_declaration
 	//			// Verilator only
 	|	yaT_RESETALL				{ }  // Else, under design, and illegal based on IEEE 22.3
@@ -6157,7 +6145,7 @@ dollarUnitNextId<nodep>:	// $unit
 	//			//     if not needed must use packageClassScopeNoId
 	//			// Must call nextId without any additional tokens following
 		yD_UNIT
-			{ $$ = new AstClassOrPackageRef($1, "$unit", GRAMMARP->unitPackage($<fl>1), nullptr);
+			{ $$ = new AstClassOrPackageRef{$1, "$unit", PARSEP->unitPackage($<fl>1), nullptr};
                           SYMP->nextId(PARSEP->rootp()); }
 	;
 
@@ -6166,7 +6154,7 @@ localNextId<nodep>:		// local
 	//			//     if not needed must use packageClassScopeNoId
 	//			// Must call nextId without any additional tokens following
 		yLOCAL__COLONCOLON
-			{ $$ = new AstClassOrPackageRef($1, "local::", GRAMMARP->unitPackage($<fl>1), nullptr);
+			{ $$ = new AstClassOrPackageRef{$1, "local::", PARSEP->unitPackage($<fl>1), nullptr};
                           SYMP->nextId(PARSEP->rootp());
 			  BBUNSUP($<fl>1, "Unsupported: Randomize 'local::'"); }
 	;

test_regress/t/t_timescale_unit.out

@@ -0,0 +1,4 @@
+Time scale of __024unit is 10ps / 10ps
+Time scale of from_unit is 10ps / 10ps
+Time scale of t is 100ps / 10ps
+*-* All Finished *-*

test_regress/t/t_timescale_unit.pl

@@ -0,0 +1,23 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 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,
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+
+1;

test_regress/t/t_timescale_unit.v

@@ -0,0 +1,30 @@
+// 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
+
+timeunit 10ps;
+timeprecision 10ps;
+
+task show;
+   $printtimescale;
+endtask
+
+module from_unit;
+   task show;
+      $printtimescale;
+   endtask
+endmodule
+
+module t;
+   from_unit from_unit();
+   timeunit 100ps;
+   initial begin
+      show();
+      from_unit.show();
+      $printtimescale;
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule