Support get_randstate/set_randstate class method function.

Changes

@@ -18,6 +18,7 @@ Verilator 5.011 devel
 
 **Minor:**
 
+* Support get_randstate/set_randstate class method function.
 * Optimize VPI callValueCbs (#4155). [Hennadii Chernyshchyk]
 * Fix crash on duplicate imported modules (#3231). [Robert Balas]
 * Fix false WIDTHEXPAND on array declarations (#3959). [JOTEGO]

include/verilated.cpp

@@ -315,15 +315,28 @@ void VlRNG::srandom(uint64_t n) VL_MT_UNSAFE {
     if (VL_COUNTONES_I(m_state[0]) < 10) m_state[0] = ~m_state[0];
     if (VL_COUNTONES_I(m_state[1]) < 10) m_state[1] = ~m_state[1];
 }
-// Unused: void VlRNG::set_randstate(const std::string& state) VL_MT_UNSAFE {
+std::string VlRNG::get_randstate() const VL_MT_UNSAFE {
-// Unused:     if (VL_LIKELY(state.length() == sizeof(m_state))) {
+    // Though not stated in IEEE, assumption is the string must be printable
-// Unused:         memcpy(m_state, state.data(), sizeof(m_state));
+    const char* const stateCharsp = reinterpret_cast<const char*>(&m_state);
-// Unused:     }
+    static_assert(sizeof(m_state) == 16);
-// Unused: }
+    std::string result{"R00112233445566770011223344556677"};
-// Unused: std::string VlRNG::get_randstate() const VL_MT_UNSAFE {
+    for (int i = 0; i < sizeof(m_state); ++i) {
-// Unused:     std::string result{reinterpret_cast<const char *>(&m_state), sizeof(m_state)};
+        result[1 + i * 2] = 'a' + ((stateCharsp[i] >> 4) & 15);
-// Unused:     return result;
+        result[1 + i * 2 + 1] = 'a' + (stateCharsp[i] & 15);
-// Unused: }
+    }
+    return result;
+}
+void VlRNG::set_randstate(const std::string& state) VL_MT_UNSAFE {
+    if (VL_UNLIKELY((state.length() != 1 + 2 * sizeof(m_state)) || (state[0] != 'R'))) {
+        VL_PRINTF_MT("%%Warning: set_randstate ignored as state string not from get_randstate\n");
+        return;
+    }
+    char* const stateCharsp = reinterpret_cast<char*>(&m_state);
+    for (int i = 0; i < sizeof(m_state); ++i) {
+        stateCharsp[i]
+            = (((state[1 + i * 2] - 'a') & 15) << 4) | ((state[1 + i * 2 + 1] - 'a') & 15);
+    }
+}
 
 static uint32_t vl_sys_rand32() VL_MT_SAFE {
     // Return random 32-bits using system library.

include/verilated_types.h

@@ -161,8 +161,8 @@ public:
     VlRNG() VL_MT_SAFE;
     explicit VlRNG(uint64_t seed0) VL_MT_SAFE : m_state{0x12341234UL, seed0} {}
     void srandom(uint64_t n) VL_MT_UNSAFE;
-    // Unused: std::string get_randstate() const VL_MT_UNSAFE;
+    std::string get_randstate() const VL_MT_UNSAFE;
-    // Unused: void set_randstate(const std::string& state) VL_MT_UNSAFE;
+    void set_randstate(const std::string& state) VL_MT_UNSAFE;
     uint64_t rand64() VL_MT_UNSAFE;
     // Threadsafe, but requires use on vl_thread_rng
     static uint64_t vl_thread_rng_rand64() VL_MT_SAFE;

src/V3LinkDot.cpp

@@ -3110,7 +3110,9 @@ private:
                     }
                 } else if (VN_IS(nodep, New) && m_statep->forPrearray()) {
                     // Resolved in V3Width
-                } else if (nodep->name() == "randomize" || nodep->name() == "srandom") {
+                } else if (nodep->name() == "randomize" || nodep->name() == "srandom"
+                           || nodep->name() == "get_randstate"
+                           || nodep->name() == "set_randstate") {
                     // Resolved in V3Width
                 } else if (nodep->dotted() == "") {
                     if (nodep->pli()) {

src/V3Width.cpp

@@ -2812,6 +2812,10 @@ private:
         return false;
     }
 
+    void visit(AstCExpr* nodep) override {
+        // Inserted by V3Width only so we know has been resolved
+        userIterateChildren(nodep, WidthVP{SELF, BOTH}.p());
+    }
     void visit(AstCMethodHard* nodep) override {
         // Never created before V3Width, so no need to redo it
         UASSERT_OBJ(nodep->dtypep(), nodep, "CMETHODCALLs should have already been sized");
@@ -2878,7 +2882,7 @@ private:
         }
         return nullptr;
     }
-    void methodOkArguments(AstMethodCall* nodep, int minArg, int maxArg) {
+    void methodOkArguments(AstNodeFTaskRef* nodep, int minArg, int maxArg) {
         int narg = 0;
         for (AstNode* argp = nodep->pinsp(); argp; argp = argp->nextp()) {
             if (VN_IS(argp, With)) {
@@ -3522,6 +3526,13 @@ private:
                     processFTaskRefArgs(nodep);
                 }
                 return;
+            } else if (nodep->name() == "get_randstate" || nodep->name() == "set_randstate") {
+                // See implementations under AstNodeFTaskRef
+                nodep->v3warn(E_UNSUPPORTED, "Unsupported: 'get_randstate'/'set_randstate' called "
+                                             "on object. Suggest call from inside class.");
+                nodep->replaceWith(new AstConst{nodep->fileline(), AstConst::BitTrue{}});
+                VL_DO_DANGLING(pushDeletep(nodep), nodep);
+                return;
             }
             classp = classp->extendsp() ? classp->extendsp()->classp() : nullptr;
         }
@@ -5537,7 +5548,9 @@ private:
         // For arguments, is assignment-like context; see IEEE rules in AstNodeAssign
         // Function hasn't been widthed, so make it so.
         UINFO(5, "  FTASKREF " << nodep << endl);
-        if (nodep->name() == "randomize" || nodep->name() == "srandom") {
+        if (nodep->name() == "randomize" || nodep->name() == "srandom"
+            || (!nodep->taskp()
+                && (nodep->name() == "get_randstate" || nodep->name() == "set_randstate"))) {
             // TODO perhaps this should move to V3LinkDot
             if (!m_classp) {
                 nodep->v3error("Calling implicit class method " << nodep->prettyNameQ()
@@ -5548,8 +5561,35 @@ private:
             }
             if (nodep->name() == "randomize") {
                 nodep->taskp(V3Randomize::newRandomizeFunc(m_classp));
-            } else {
+            } else if (nodep->name() == "srandom") {
                 nodep->taskp(V3Randomize::newSRandomFunc(m_classp));
+            } else if (nodep->name() == "get_randstate") {
+                methodOkArguments(nodep, 0, 0);
+                m_classp->baseMostClassp()->needRNG(true);
+                v3Global.useRandomizeMethods(true);
+                AstCExpr* const newp
+                    = new AstCExpr{nodep->fileline(), "__Vm_rng.get_randstate()", 1, true};
+                newp->dtypeSetString();
+                nodep->replaceWith(newp);
+                VL_DO_DANGLING(pushDeletep(nodep), nodep);
+                return;
+            } else if (nodep->name() == "set_randstate") {
+                methodOkArguments(nodep, 1, 1);
+                AstNodeExpr* const expr1p = VN_AS(nodep->pinsp(), Arg)->exprp();  // May edit
+                iterateCheckString(nodep, "LHS", expr1p, BOTH);
+                AstNodeExpr* const exprp = VN_AS(nodep->pinsp(), Arg)->exprp();
+                m_classp->baseMostClassp()->needRNG(true);
+                v3Global.useRandomizeMethods(true);
+                AstCExpr* const newp
+                    = new AstCExpr{nodep->fileline(), "__Vm_rng.set_randstate(", 1, true};
+                newp->addExprsp(exprp->unlinkFrBack());
+                newp->addExprsp(new AstText{nodep->fileline(), ")", true});
+                newp->dtypeSetString();
+                nodep->replaceWith(newp);
+                VL_DO_DANGLING(pushDeletep(nodep), nodep);
+                return;
+            } else {
+                UASSERT_OBJ(false, nodep, "Bad case");
             }
         }
         UASSERT_OBJ(nodep->taskp(), nodep, "Unlinked");

test_regress/t/t_randstate_func.pl

@@ -0,0 +1,21 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2020 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
+
+scenarios(simulator => 1);
+
+compile(
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;

test_regress/t/t_randstate_func.v

@@ -0,0 +1,48 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+class Cls;
+   rand int length;
+
+   function void test;
+      automatic int rand_result, v1, v2;
+      automatic string s;
+
+      // UVM 2023 does a print, so check is ascii
+      $display("get_randstate = '%s'", get_randstate());
+
+      s = get_randstate();
+
+      rand_result = randomize();
+      if (rand_result != 1) $stop;
+      v1 = length;
+
+      set_randstate(s);
+
+      rand_result = randomize();
+      if (rand_result != 1) $stop;
+      v2 = length;
+
+`ifdef VERILATOR  // About half of the other simulators fail at this
+      if (v1 != v2) $stop;
+`endif
+   endfunction
+endclass
+
+module t(/*AUTOARG*/);
+
+   automatic int rand_result, v1, v2;
+   automatic string s;
+
+   initial begin
+      Cls c;
+      c = new;
+      c.test;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule

test_regress/t/t_randstate_obj.out

@@ -0,0 +1,10 @@
+%Error-UNSUPPORTED: t/t_randstate_obj.v:20:13: Unsupported: 'get_randstate'/'set_randstate' called on object. Suggest call from inside class.
+                                             : ... In instance t
+   20 |       s = c.get_randstate();
+      |             ^~~~~~~~~~~~~
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error-UNSUPPORTED: t/t_randstate_obj.v:26:9: Unsupported: 'get_randstate'/'set_randstate' called on object. Suggest call from inside class.
+                                            : ... In instance t
+   26 |       c.set_randstate(s);
+      |         ^~~~~~~~~~~~~
+%Error: Exiting due to

test_regress/t/t_randstate_obj.pl

@@ -0,0 +1,19 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2020 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
+
+scenarios(simulator => 1);
+
+compile(
+    expect_filename => $Self->{golden_filename},
+    fails => $Self->{vlt_all},
+    );
+
+ok(1);
+1;

test_regress/t/t_randstate_obj.v

@@ -0,0 +1,39 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+class Cls;
+   rand int length;
+endclass
+
+module t(/*AUTOARG*/);
+
+   automatic int rand_result, v1, v2;
+   automatic string s;
+
+   initial begin
+      Cls c;
+      c = new;
+
+      s = c.get_randstate();
+
+      rand_result = c.randomize();
+      if (rand_result != 1) $stop;
+      v1 = c.length;
+
+      c.set_randstate(s);
+
+      rand_result = c.randomize();
+      if (rand_result != 1) $stop;
+      v2 = c.length;
+
+`ifdef VERILATOR  // About half of the other simulators fail at this
+      if (v1 != v2) $stop;
+`endif
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule

test_regress/t/t_randstate_seed_bad.out

@@ -0,0 +1,2 @@
+%Warning: set_randstate ignored as state string not from get_randstate
+*-* All Finished *-*

test_regress/t/t_randstate_seed_bad.pl

@@ -0,0 +1,21 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2020 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
+
+scenarios(vlt => 1);
+
+compile(
+    );
+
+execute(
+    expect_filename => $Self->{golden_filename},
+    );
+
+ok(1);
+1;

test_regress/t/t_randstate_seed_bad.v

@@ -0,0 +1,28 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+class Cls;
+   function void test;
+      automatic string s;
+
+      s = get_randstate();
+      // Vlt only result check
+      if (s[0] !== "R") $fatal(2, $sformatf("Bad get_randstate = '%s'", s));
+
+      set_randstate("000bad");  // Bad
+   endfunction
+endclass
+
+module t(/*AUTOARG*/);
+
+   initial begin
+      Cls c;
+      c = new;
+      c.test;
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule