Fix false TIMESCALEMOD on generate-ignored instances (#2838).

Changes

@@ -20,6 +20,7 @@ Verilator 4.201 devel
 * Fix exceeding command-line ar limit (#2834). [Yinan Xu]
 * Fix false $dumpfile warning on model save (#2834). [Yinan Xu]
 * Fix --timescale-override not suppressing TIMESCALEMOD (#2838). [Kaleb Barrett]
+* Fix false TIMESCALEMOD on generate-ignored instances (#2838). [Kaleb Barrett]
 
 
 Verilator 4.200 2021-03-12

bin/verilator

@@ -1509,8 +1509,8 @@ good value.
 =item --timescale I<timeunit>/I<timeprecision>
 
 Sets default timescale, timeunit and timeprecision for when `timescale does
-not occur in sources.  Default is "1ps/1ps" (to match SystemC).  This is
-overridden by C<--timescale-override>.
+not occur before a given module.  Default is "1ps/1ps" (to match SystemC).
+This is overridden by C<--timescale-override>.
 
 =item --timescale-override I<timeunit>/I<timeprecision>
 

src/V3Ast.h

@@ -2880,6 +2880,7 @@ public:
     virtual void dump(std::ostream& str) const override;
     virtual bool maybePointedTo() const override { return true; }
     virtual string name() const override { return m_name; }
+    virtual bool timescaleMatters() const = 0;
     AstNode* stmtsp() const { return op2p(); }  // op2 = List of statements
     AstActive* activesp() const { return VN_CAST(op3p(), Active); }  // op3 = List of i/sblocks
     // METHODS

src/V3AstNodes.h

@@ -290,6 +290,7 @@ public:
     ASTNODE_NODE_FUNCS(ClassPackage)
     virtual string verilogKwd() const override { return "/*class*/package"; }
     virtual const char* broken() const override;
+    virtual bool timescaleMatters() const override { return false; }
     AstClass* classp() const { return m_classp; }
     void classp(AstClass* classp) { m_classp = classp; }
 };
@@ -317,6 +318,7 @@ public:
         BROKEN_RTN(m_classOrPackagep && !m_classOrPackagep->brokeExists());
         return nullptr;
     }
+    virtual bool timescaleMatters() const override { return false; }
     // op1/op2/op3 in AstNodeModule
     AstClassPackage* classOrPackagep() const { return m_classOrPackagep; }
     void classOrPackagep(AstClassPackage* classpackagep) { m_classOrPackagep = classpackagep; }
@@ -2559,6 +2561,7 @@ public:
         , m_isProgram{program} {}
     ASTNODE_NODE_FUNCS(Module)
     virtual string verilogKwd() const override { return m_isProgram ? "program" : "module"; }
+    virtual bool timescaleMatters() const override { return true; }
 };
 
 class AstNotFoundModule final : public AstNodeModule {
@@ -2568,6 +2571,7 @@ public:
         : ASTGEN_SUPER(fl, name) {}
     ASTNODE_NODE_FUNCS(NotFoundModule)
     virtual string verilogKwd() const override { return "/*not-found-*/ module"; }
+    virtual bool timescaleMatters() const override { return false; }
 };
 
 class AstPackage final : public AstNodeModule {
@@ -2577,6 +2581,7 @@ public:
         : ASTGEN_SUPER(fl, name) {}
     ASTNODE_NODE_FUNCS(Package)
     virtual string verilogKwd() const override { return "package"; }
+    virtual bool timescaleMatters() const override { return !isDollarUnit(); }
     static string dollarUnitName() { return AstNode::encodeName("$unit"); }
     bool isDollarUnit() const { return name() == dollarUnitName(); }
 };
@@ -2588,6 +2593,7 @@ public:
         : ASTGEN_SUPER(fl, name) {}
     ASTNODE_NODE_FUNCS(Primitive)
     virtual string verilogKwd() const override { return "primitive"; }
+    virtual bool timescaleMatters() const override { return false; }
 };
 
 class AstPackageExportStarStar final : public AstNode {
@@ -2653,6 +2659,9 @@ public:
     AstIface(FileLine* fl, const string& name)
         : ASTGEN_SUPER(fl, name) {}
     ASTNODE_NODE_FUNCS(Iface)
+    // Interfaces have `timescale applicability but lots of code seems to
+    // get false warnings if we enable this
+    virtual bool timescaleMatters() const override { return false; }
 };
 
 class AstMemberSel final : public AstNodeMath {

src/V3LinkLevel.cpp

@@ -101,13 +101,13 @@ void V3LinkLevel::timescaling(const ModVec& mods) {
     v3Global.rootp()->timeunit(unit);
 
     for (AstNodeModule* nodep : mods) {
+        if (!v3Global.opt.timeOverrideUnit().isNone()) nodep->timeunit(unit);
         if (nodep->timeunit().isNone()) {
             if (modTimedp  // Got previous
                 && (  // unit doesn't already include an override
                     v3Global.opt.timeOverrideUnit().isNone()
                     && v3Global.opt.timeDefaultUnit().isNone())
-                && (!VN_IS(nodep, Iface) && !VN_IS(nodep, Primitive)
-                    && !(VN_IS(nodep, Package) && VN_CAST(nodep, Package)->isDollarUnit()))) {
+                && nodep->timescaleMatters()) {
                 nodep->v3warn(TIMESCALEMOD,
                               "Timescale missing on this module as other modules have "
                               "it (IEEE 1800-2017 3.14.2.3)\n"

test_regress/t/t_flag_timescale_override.out

@@ -1,2 +1,3 @@
 Time scale of t is 1ms / 1us
+Time scale of sub is 1ms / 1us
 *-* All Finished *-*

test_regress/t/t_flag_timescale_override.v

@@ -7,9 +7,17 @@
 `timescale 1s/1s
 
 module t;
+   sub sub ();
    initial begin
       $printtimescale;
+      sub.pts();
       $write("*-* All Finished *-*\n");
       $finish;
    end
 endmodule
+
+module sub;
+   task pts;
+      $printtimescale;
+   endtask
+endmodule

test_regress/t/t_flag_timescale_override2.out

@@ -1,2 +1,3 @@
 Time scale of t is 1s / 1us
+Time scale of sub is 1s / 1us
 *-* All Finished *-*

test_regress/t/t_hier_block.pl

@@ -20,6 +20,7 @@ compile(
     v_flags2 => ['t/t_hier_block.cpp'],
     verilator_flags2 => ['--stats', ($Self->{vltmt} ? ' --threads 6' : ''),
                          '--hierarchical',
+                         '--Wno-TIMESCALEMOD',
                          '--CFLAGS', '"-pipe -DCPP_MACRO=cplusplus"'
     ],
     );

test_regress/t/t_sv_cpu.pl

@@ -34,7 +34,8 @@ compile(
                  "t/t_sv_cpu_code/cpu.sv",
                  "t/t_sv_cpu_code/chip.sv"],
     vcs_flags2 => ["-R -sverilog +memcbk -y t/t_sv_cpu_code +libext+.sv+ +incdir+t/t_sv_cpu_code"],
-    verilator_flags2 => ["-y t/t_sv_cpu_code +libext+.sv+ +incdir+t/t_sv_cpu_code --top-module t"],
+    verilator_flags2 => ["-y t/t_sv_cpu_code +libext+.sv+ +incdir+t/t_sv_cpu_code --top-module t",
+                         "--timescale-override 1ns/1ps"],
     iv_flags2 => ["-yt/t_sv_cpu_code -It/t_sv_cpu_code -Y.sv"],
     );
 

test_regress/t/t_timescale_udp.v

@@ -7,10 +7,18 @@
 `timescale 1ns/1ns
 module t;
    p p ();
+
+   // Also check not-found modules
+   localparam NOT = 0;
+   if (NOT) begin
+      NotFound not_found(.*);
+   end
+
    initial begin
       $write("*-* All Finished *-*\n");
       $finish;
    end
+
 endmodule
 
 `timescale 1ns/1ns