Allow for non-const RHS in ==?

Signed-off-by: Ryszard Rozak <[email protected]>
antmicro · Dec 11, 2024 · 8876de4 · 8876de4
1 parent 9656311
commit 8876de4
Showing 1 changed file with 12 additions and 19 deletions.
diff --git a/src/V3Unknown.cpp b/src/V3Unknown.cpp
@@ -236,27 +236,20 @@ class UnknownVisitor final : public VNVisitor {
             AstNodeExpr* const lhsp = nodep->lhsp()->unlinkFrBack();
             AstNodeExpr* const rhsp = nodep->rhsp()->unlinkFrBack();
             AstNodeExpr* newp;
-            if (!VN_IS(rhsp, Const)) {
-                nodep->v3warn(E_UNSUPPORTED, "Unsupported: RHS of ==? or !=? must be "
-                                             "constant to be synthesizable");  // Says spec.
-                // Replace with anything that won't cause more errors
-                newp = new AstEq{nodep->fileline(), lhsp, rhsp};
+            // X or Z's become mask, ala case statements.
+            V3Number nummask{rhsp, rhsp->width()};
+            nummask.opBitsNonX(VN_AS(rhsp, Const)->num());
+            V3Number numval{rhsp, rhsp->width()};
+            numval.opBitsOne(VN_AS(rhsp, Const)->num());
+            AstNodeExpr* const and1p
+                = new AstAnd{nodep->fileline(), lhsp, new AstConst{nodep->fileline(), nummask}};
+            AstNodeExpr* const and2p = new AstConst{nodep->fileline(), numval};
+            if (VN_IS(nodep, EqWild)) {
+                newp = new AstEq{nodep->fileline(), and1p, and2p};
             } else {
-                // X or Z's become mask, ala case statements.
-                V3Number nummask{rhsp, rhsp->width()};
-                nummask.opBitsNonX(VN_AS(rhsp, Const)->num());
-                V3Number numval{rhsp, rhsp->width()};
-                numval.opBitsOne(VN_AS(rhsp, Const)->num());
-                AstNodeExpr* const and1p = new AstAnd{nodep->fileline(), lhsp,
-                                                      new AstConst{nodep->fileline(), nummask}};
-                AstNodeExpr* const and2p = new AstConst{nodep->fileline(), numval};
-                if (VN_IS(nodep, EqWild)) {
-                    newp = new AstEq{nodep->fileline(), and1p, and2p};
-                } else {
-                    newp = new AstNeq{nodep->fileline(), and1p, and2p};
-                }
-                VL_DO_DANGLING(rhsp->deleteTree(), rhsp);
+                newp = new AstNeq{nodep->fileline(), and1p, and2p};
             }
+            VL_DO_DANGLING(rhsp->deleteTree(), rhsp);
             nodep->replaceWith(newp);
             VL_DO_DANGLING(nodep->deleteTree(), nodep);
             // Iterate tree now that we may have gotten rid of the compare