Support elaboration-time printing of unpacked array with `%p` (#4732).

Changes

@@ -100,6 +100,7 @@ Verilator 5.038 2025-07-08
 
 * Support redeclaring type as non-type; major parsing change (#2412) (#6020) (#6042) (#6044).
 * Support scoped `new` (#4199).
+* Support elaboration-time printing of unpacked array with `%p` (#4732).
 * Support constrained random for associative arrays (#5985) (#5986). [Yilou Wang]
 * Support assignments to concatenations with impure RHS (#6002). [Ryszard Rozak, Antmicro Ltd.]
 * Support SARIF JSON diagnostic output with `--diagnostics-sarif`. (#6017)

src/V3Const.cpp

@@ -2521,6 +2521,22 @@ class ConstVisitor final : public VNVisitor {
         VL_DO_DANGLING(pushDeletep(nodep), nodep);
         return true;
     }
+    bool matchToStringNConst(AstToStringN* nodep) {
+        iterateChildren(nodep);
+        if (AstInitArray* const initp = VN_CAST(nodep->lhsp(), InitArray)) {
+            if (!(m_doExpensive || m_params)) return false;
+            // At present only support 1D unpacked arrays
+            const auto initOfConst = [](const AstNode* const nodep) -> bool {  //
+                return VN_IS(nodep, Const) || VN_IS(nodep, InitItem);
+            };
+            if (initp->initsp() && !initp->initsp()->forall(initOfConst)) return false;
+            if (initp->defaultp() && !initp->defaultp()->forall(initOfConst)) return false;
+        } else if (!VN_IS(nodep->lhsp(), Const)) {
+            return false;
+        }
+        replaceWithSimulation(nodep);
+        return true;
+    }
     int operandConcatMove(const AstConcat* nodep) {
         //    CONCAT under concat  (See moveConcat)
         // Return value: true indicates to do it; 2 means move to LHS
@@ -3892,6 +3908,7 @@ class ConstVisitor final : public VNVisitor {
     TREEOPA("AstPutcN{$lhsp.castConst, $rhsp.castConst, $thsp.castConst}",  "replaceConst(nodep)");
     TREEOPA("AstSubstrN{$lhsp.castConst, $rhsp.castConst, $thsp.castConst}",  "replaceConst(nodep)");
     TREEOPA("AstCvtPackString{$lhsp.castConst}", "replaceConstString(nodep, VN_AS(nodep->lhsp(), Const)->num().toString())");
+    TREEOP ("AstToStringN{matchToStringNConst(nodep)}", "DONE");
     // Custom
     // Implied by AstIsUnbounded::numberOperate: V("AstIsUnbounded{$lhsp.castConst}", "replaceNum(nodep, 0)");
     TREEOPV("AstIsUnbounded{$lhsp.castUnbounded}", "replaceNum(nodep, 1)");

src/V3Simulate.h

@@ -410,6 +410,40 @@ private:
         }
     }
 
+    string toStringRecurse(AstNodeExpr* nodep) {
+        // Return string representation, or clearOptimizable
+        const AstNodeExpr* const valuep = fetchValue(nodep);
+        if (const AstConst* const avaluep = VN_CAST(valuep, Const)) {
+            return "'h"s + avaluep->num().displayed(nodep, "%0x");
+        }
+        if (const AstInitArray* const avaluep = VN_CAST(valuep, InitArray)) {
+            string result = "'{";
+            string comma;
+            if (VN_IS(nodep->dtypep(), AssocArrayDType)) {
+                if (avaluep->defaultp()) {
+                    result += comma + "default:" + toStringRecurse(avaluep->defaultp());
+                    comma = ", ";
+                }
+                const auto& mapr = avaluep->map();
+                for (const auto& itr : mapr) {
+                    result += comma + cvtToStr(itr.first) + ":"
+                              + toStringRecurse(itr.second->valuep());
+                    comma = ", ";
+                }
+            } else if (const AstUnpackArrayDType* const dtypep
+                       = VN_CAST(nodep->dtypep(), UnpackArrayDType)) {
+                for (int n = 0; n < dtypep->elementsConst(); ++n) {
+                    result += comma + toStringRecurse(avaluep->getIndexDefaultedValuep(n));
+                    comma = ", ";
+                }
+            }
+            result += "}";
+            return result;
+        }
+        clearOptimizable(nodep, "Cannot convert to string");  // LCOV_EXCL_LINE
+        return "";
+    }
+
     // VISITORS
     void visit(AstAlways* nodep) override {
         if (jumpingOver()) return;
@@ -1265,7 +1299,12 @@ private:
         if (!optimizable()) return;  // Accelerate
         checkNodeInfo(nodep);
         iterateChildrenConst(nodep);
-        clearOptimizable(nodep, "Cannot convert to string");  // LCOV_EXCL_LINE
+        if (!optimizable()) return;
+        std::string result = toStringRecurse(nodep->lhsp());
+        if (!optimizable()) return;
+        AstConst* const resultConstp = new AstConst{nodep->fileline(), AstConst::String{}, result};
+        setValue(nodep, resultConstp);
+        m_reclaimValuesp.push_back(resultConstp);
     }
 
     void visit(AstCoverInc* nodep) override { m_isCoverage = true; }

test_regress/t/t_display_p_elab.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2024 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
+
+import vltest_bootstrap
+
+test.scenarios('simulator_st')
+
+test.compile(verilator_flags2=['--binary'])
+
+test.execute()
+
+test.passes()

test_regress/t/t_display_p_elab.v

@@ -0,0 +1,77 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+// verilog_format: off
+`define stop $stop
+`define checks(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got='%s' exp='%s'\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
+`ifdef verilator
+ `define no_optimize(v) $c(v)
+`else
+ `define no_optimize(v) (v)
+`endif
+// verilog_format: on
+
+
+module t;
+
+  // $sformatf is not supported as parameter by some simulators
+
+  parameter int I = 234;
+  parameter string IS = $sformatf(">%p<", I);
+  initial `checks(IS, ">       234<");
+
+  parameter real R = 1.234;
+  parameter string RS = $sformatf(">%p<", R);
+  initial `checks(RS, ">1.234<");
+
+  int u[2];
+  parameter int U[2] = '{5, 6};
+  parameter string US = $sformatf(">%p<", U);
+  initial `checks(US, ">'{'h5, 'h6}<");
+
+`ifndef VERILATOR
+  // Generally not supported by others
+  parameter int Q[$] = '{1, 2};
+  parameter string QS = $sformatf(">%p<", Q);
+  initial `checks(QS, "x");
+
+  // Generally not supported by others
+  parameter int D[] = '{1, 2};
+  parameter string DS = $sformatf(">%p<", D);
+  initial `checks(DS, ">'{1, 2}<");
+
+  parameter int A[int] = '{1: 10, 2: 20};
+  parameter string AS = $sformatf(">%p<", A);
+  initial `checks(AS, "x");
+
+  typedef struct {int f, s;} s_t;
+  parameter s_t S = '{f: 10, s: 20};
+  parameter string SS = $sformatf(">%p<", S);
+  initial `checks(SS, ">'{f:10, s:20}<");
+`endif
+
+  // Original issue
+  function integer infofunc();
+    $info("%p", U);
+    return 0;
+  endfunction
+  localparam integer return_val = infofunc();
+
+  string s;
+
+  initial begin
+    #1;
+    u[0] = `no_optimize(5);
+    u[1] = `no_optimize(6);
+    s = $sformatf(">%p<", u);
+    `checks(s, ">'{'h5, 'h6}<");
+
+    `checks(US, ">'{'h5, 'h6}<");
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+
+endmodule