Fix cast width propagation (#2597).

Changes

@@ -16,6 +16,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix iteration over mutating list bug in VPI (#2588). [Kaleb Barrett]
 
+****  Fix cast width propagation (#2597). [flex-liu]
+
 ****  Fix return from callValueCbs (#2589) (#2605). [Marlon James]
 
 ****  Fix WIDTH warnings on comparisons with nullptr (#2602). [Rupert Swarbrick]

src/V3AstNodes.h

@@ -5953,6 +5953,7 @@ public:
     virtual bool cleanLhs() const { return true; }
     virtual bool sizeMattersLhs() const { return false; }
     AstNode* lhsp() const { return op1p(); }
+    void lhsp(AstNode* nodep) { setOp1p(nodep); }
     virtual AstNodeDType* getChildDTypep() const override { return childDTypep(); }
     AstNodeDType* childDTypep() const { return VN_CAST(op2p(), NodeDType); }
     virtual AstNodeDType* subDTypep() const { return dtypep() ? dtypep() : childDTypep(); }

src/V3Width.cpp

@@ -1661,14 +1661,14 @@ private:
         // Note we don't sign lhsp() that would make the algorithm O(n^2) if lots of casting.
         AstBasicDType* basicp = nodep->dtypep()->basicp();
         UASSERT_OBJ(basicp, nodep, "Unimplemented: Casting non-simple data type");
+        if (m_vup->prelim()) {
+            userIterateAndNext(nodep->lhsp(), WidthVP(SELF, PRELIM).p());
             // When implement more complicated types need to convert childDTypep to
             // dtypep() not as a child
             if (!basicp->isDouble() && !nodep->lhsp()->isDouble()) {
-            // Note widthCheckSized might modify nodep->lhsp()
+                // Note castSized might modify nodep->lhsp()
-            AstNodeDType* subDTypep = nodep->findLogicDType(nodep->width(), nodep->width(),
+                int width = nodep->dtypep()->width();
-                                                            nodep->lhsp()->dtypep()->numeric());
+                castSized(nodep, nodep->lhsp(), width);
-            iterateCheck(nodep, "value", nodep->lhsp(), CONTEXT, FINAL, subDTypep, EXTEND_EXP,
-                         false);
             } else {
                 iterateCheck(nodep, "value", nodep->lhsp(), SELF, FINAL, nodep->lhsp()->dtypep(),
                              EXTEND_EXP, false);
@@ -1684,7 +1684,8 @@ private:
                 if (basicp->isSigned()) {
                     newp = new AstRToIRoundS(nodep->fileline(), newp);
                 } else {
-                newp = new AstUnsigned(nodep->fileline(), new AstRToIS(nodep->fileline(), newp));
+                    newp = new AstUnsigned(nodep->fileline(),
+                                           new AstRToIS(nodep->fileline(), newp));
                 }
             } else if (basicp->isSigned() && !newp->isSigned()) {
                 newp = new AstSigned(nodep->fileline(), newp);
@@ -1693,9 +1694,14 @@ private:
             } else {
                 // newp = newp;  // Can just remove cast
             }
-        nodep->replaceWith(newp);
+            nodep->lhsp(newp);
+            // if (debug()) nodep->dumpTree(cout, "  CastOut: ");
+        }
+        if (m_vup->final()) {
+            AstNode* underp = nodep->lhsp()->unlinkFrBack();
+            nodep->replaceWith(underp);
             VL_DO_DANGLING(pushDeletep(nodep), nodep);
-        // if (debug()) newp->dumpTree(cout, "  CastOut: ");
+        }
     }
     virtual void visit(AstCastSize* nodep) override {
         // IEEE: Signedness of result is same as self-determined signedness

test_regress/t/t_math_shift_extend.v

@@ -9,9 +9,14 @@ module t (/*AUTOARG*/);
    logic in1 = 1;
    logic [1:0] in2 = 2'b11;
    logic [31:0] out;
+   logic [7:0]  ones = 8'b11111111;
+   logic [9:0]  ones10 = 10'b1111111111;
 
    typedef logic [7:0] data_t;
 
+   typedef logic [9:0] ten_t;
+   ten_t out10;
+
    // verilator lint_off WIDTH
    initial begin
       in1 = 1;
@@ -31,6 +36,28 @@ module t (/*AUTOARG*/);
       out = data_t'(in1 << in2);
       if (out != 8'b1000) $stop;
 
+      // Check upper bits get cleared when cast
+      in2 = 3;
+      out = data_t'(ones << in2);
+      if (out != 8'b11111000) $stop;
+
+      in2 = 3;
+      out = data_t'(ones10 << in2);
+      if (out != 8'b11111000) $stop;
+
+      // bug2597
+      out = data_t'(10'h208 >> 2);
+      if (out != 8'h82) $stop;
+
+      out = data_t'(10'h208 >> 2);
+      if (out != 8'h82) $stop;
+
+      out = data_t'('h208 >> 2);
+      if (out != 8'h82) $stop;
+
+      out10 = ten_t'('h404 >> 2);
+      if (out10 != 10'h101) $stop;
+
       $write("*-* All Finished *-*\n");
       $finish();
    end