Fix member select of variable without randmode (#6800) (#6833)

src/V3Randomize.cpp

@@ -892,18 +892,25 @@ class ConstraintExprVisitor final : public VNVisitor {
             AstNodeExpr* constFormatp
                 = membersel ? getConstFormat(membersel->cloneTree(false)) : getConstFormat(nodep);
 
-            // Build randmode access: for membersel, access parent object's __Vrandmode
+            // Build randmode access: for membersel, use member's class randmode if available
             AstNodeExpr* randModeAccess;
             if (membersel) {
-                AstNodeExpr* parentAccess = membersel->fromp()->cloneTree(false);
                 AstNodeModule* const varClassp = VN_AS(varp->user2p(), NodeModule);
                 AstVar* const effectiveRandModeVarp = VN_AS(varClassp->user2p(), Var);
-                UASSERT_OBJ(effectiveRandModeVarp, nodep,
-                            "Member-selected variable must have randmode in its class");
+                if (effectiveRandModeVarp) {
+                    // Member's class has randmode, use it
+                    AstNodeExpr* parentAccess = membersel->fromp()->cloneTree(false);
                     AstMemberSel* randModeSel
                         = new AstMemberSel{varp->fileline(), parentAccess, effectiveRandModeVarp};
                     randModeSel->dtypep(effectiveRandModeVarp->dtypep());
                     randModeAccess = randModeSel;
+                } else {
+                    // Member's class has no randmode, use current scope's randmode
+                    UASSERT_OBJ(m_randModeVarp, nodep, "No m_randModeVarp");
+                    randModeAccess = new AstVarRef{varp->fileline(),
+                                                   VN_AS(m_randModeVarp->user2p(), NodeModule),
+                                                   m_randModeVarp, VAccess::READ};
+                }
             } else {
                 UASSERT_OBJ(m_randModeVarp, nodep, "No m_randModeVarp");
                 randModeAccess

test_regress/t/t_constraint_global_randMode.v

@@ -21,14 +21,65 @@ endclass
 class Foo extends Base;
 endclass
 
-module t;
+package uvm_pkg;
+  virtual class uvm_object;
+  endclass
+
+  class uvm_sequence_item;
+  endclass
+
+  virtual class uvm_sequencer_param_base;
+    function void send_request(uvm_sequence_item t);
+      uvm_sequence_item par;
+      if (0 == par.randomize()) begin
+      end
+    endfunction
+  endclass
+
+  class uvm_reg_item extends uvm_sequence_item;
+    rand uvm_object extension;
+  endclass
+
+  class uvm_reg_field extends uvm_object;
+    rand int value;
+    virtual function bit get_rand_mode();
+      return bit'(value.rand_mode());
+    endfunction
+  endclass
+
+endpackage
+
+module t_constraint_global_randMode;
+  import uvm_pkg::*;
+
+  class reg_r extends uvm_object;
+    rand int value;
+    local rand uvm_reg_field _dummy;
+    constraint _dummy_is_reg {_dummy.value == value;}
+    function new();
+      _dummy = new;
+    endfunction
+  endclass
+
   initial begin
-    Foo d = new;
-    Base b = d;
+    Foo d;
+    Base b;
+    reg_r r;
+
+    // Test 1: Member class with randmode
+    d = new;
+    b = d;
     b.v.disable_val();
     b.v.value = 11;
+    /* verilator lint_off WIDTHTRUNC */
     if (bit'(b.randomize())) $stop;
     if (b.v.value != 11) $stop;
+
+    // Test 2: Member class without randmode
+    r = new;
+    if (!r.randomize()) $stop;
+    /* verilator lint_on WIDTHTRUNC */
+
     $write("*-* All Finished *-*\n");
     $finish;
   end