Fix splitting eval functions with --output-split-cfuncs (#2368).

Changes

@@ -19,6 +19,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Fix class constructor error on assignments to const.
 
+****  Fix splitting eval functions with --output-split-cfuncs (#2368). [Geza Lore]
+
 
 * Verilator 4.040 2020-08-15
 

src/V3Clock.cpp

@@ -160,6 +160,43 @@ private:
         m_lastSenp = nullptr;
         m_lastIfp = nullptr;
     }
+    void splitCheck(AstCFunc* ofuncp) {
+        if (!v3Global.opt.outputSplitCFuncs() || !ofuncp->stmtsp()) return;
+        if (EmitCBaseCounterVisitor(ofuncp->stmtsp()).count() < v3Global.opt.outputSplitCFuncs())
+            return;
+
+        int funcnum = 0;
+        int func_stmts = 0;
+        AstCFunc* funcp = nullptr;
+
+        // Unlink all statements, then add item by item to new sub-functions
+        AstBegin* tempp = new AstBegin{ofuncp->fileline(), "[EditWrapper]",
+                                       ofuncp->stmtsp()->unlinkFrBackWithNext()};
+        if (ofuncp->finalsp()) tempp->addStmtsp(ofuncp->finalsp()->unlinkFrBackWithNext());
+        while (tempp->stmtsp()) {
+            AstNode* itemp = tempp->stmtsp()->unlinkFrBack();
+            int stmts = EmitCBaseCounterVisitor(itemp).count();
+            if (!funcp || (func_stmts + stmts) > v3Global.opt.outputSplitCFuncs()) {
+                // Make a new function
+                funcp = new AstCFunc{ofuncp->fileline(), ofuncp->name() + cvtToStr(++funcnum),
+                                     m_topScopep->scopep()};
+                funcp->argTypes(EmitCBaseVisitor::symClassVar());
+                funcp->dontCombine(true);
+                funcp->symProlog(true);
+                funcp->isStatic(true);
+                funcp->slow(ofuncp->slow());
+                m_topScopep->scopep()->addActivep(funcp);
+                //
+                AstCCall* callp = new AstCCall{funcp->fileline(), funcp};
+                callp->argTypes("vlSymsp");
+                ofuncp->addStmtsp(callp);
+                func_stmts = 0;
+            }
+            funcp->addStmtsp(itemp);
+            func_stmts += stmts;
+        }
+        VL_DO_DANGLING(tempp->deleteTree(), tempp);
+    }
 
     // VISITORS
     virtual void visit(AstTopScope* nodep) override {
@@ -172,28 +209,29 @@ private:
         AstNode::user1ClearTree();
         // Make top functions
         {
-            AstCFunc* funcp = new AstCFunc(nodep->fileline(), "_eval", m_scopep);
+            AstCFunc* funcp = new AstCFunc{nodep->fileline(), "_eval", m_topScopep->scopep()};
             funcp->argTypes(EmitCBaseVisitor::symClassVar());
             funcp->dontCombine(true);
             funcp->symProlog(true);
             funcp->isStatic(true);
             funcp->entryPoint(true);
-            m_scopep->addActivep(funcp);
+            m_topScopep->scopep()->addActivep(funcp);
             m_evalFuncp = funcp;
         }
         {
-            AstCFunc* funcp = new AstCFunc(nodep->fileline(), "_eval_initial", m_scopep);
+            AstCFunc* funcp
+                = new AstCFunc{nodep->fileline(), "_eval_initial", m_topScopep->scopep()};
             funcp->argTypes(EmitCBaseVisitor::symClassVar());
             funcp->dontCombine(true);
             funcp->slow(true);
             funcp->symProlog(true);
             funcp->isStatic(true);
             funcp->entryPoint(true);
-            m_scopep->addActivep(funcp);
+            m_topScopep->scopep()->addActivep(funcp);
             m_initFuncp = funcp;
         }
         {
-            AstCFunc* funcp = new AstCFunc(nodep->fileline(), "final", m_scopep);
+            AstCFunc* funcp = new AstCFunc{nodep->fileline(), "final", m_topScopep->scopep()};
             funcp->skipDecl(true);
             funcp->dontCombine(true);
             funcp->slow(true);
@@ -204,22 +242,29 @@ private:
                                                                  + " = this->__VlSymsp;\n"));
             funcp->addInitsp(
                 new AstCStmt(nodep->fileline(), EmitCBaseVisitor::symTopAssign() + "\n"));
-            m_scopep->addActivep(funcp);
+            m_topScopep->scopep()->addActivep(funcp);
             m_finalFuncp = funcp;
         }
         {
-            AstCFunc* funcp = new AstCFunc(nodep->fileline(), "_eval_settle", m_scopep);
+            AstCFunc* funcp
+                = new AstCFunc{nodep->fileline(), "_eval_settle", m_topScopep->scopep()};
             funcp->argTypes(EmitCBaseVisitor::symClassVar());
             funcp->dontCombine(true);
             funcp->slow(true);
             funcp->isStatic(true);
             funcp->symProlog(true);
             funcp->entryPoint(true);
-            m_scopep->addActivep(funcp);
+            m_topScopep->scopep()->addActivep(funcp);
             m_settleFuncp = funcp;
         }
         // Process the activates
         iterateChildren(nodep);
+        UINFO(4, " TOPSCOPE iter done " << nodep << endl);
+        // Split large functions
+        splitCheck(m_evalFuncp);
+        splitCheck(m_initFuncp);
+        splitCheck(m_finalFuncp);
+        splitCheck(m_settleFuncp);
         // Done, clear so we can detect errors
         UINFO(4, " TOPSCOPEDONE " << nodep << endl);
         clearLastSen();

test_regress/t/t_flag_csplit_eval.pl

@@ -0,0 +1,40 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 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
+
+sub check_evals {
+    my $got = 0;
+    foreach my $file (glob("$Self->{obj_dir}/*.cpp")) {
+        my $fh = IO::File->new("<$file");
+        local $/; undef $/;
+        my $wholefile = <$fh>;
+
+        if ($wholefile =~ /::_eval[0-9]+/) {
+            ++$got;
+        }
+    }
+    $got >= 3 or error("Too few _eval functions found: $got");
+}
+
+
+scenarios(vlt_all => 1);
+
+compile(
+    v_flags2 => ["--output-split 1 --output-split-cfuncs 1 --exe ../$Self->{main_filename}"],
+#    verilator_make_gmake => 0,
+    );
+
+# Very slow to compile, so generally skip it
+execute(
+    check_finished => 1,
+    );
+
+check_evals();
+ok(1);
+1;

test_regress/t/t_flag_csplit_eval.v

@@ -0,0 +1,31 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2005 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t (/*AUTOARG*/
+   // Outputs
+   cnt0, cnt1,
+   // Inputs
+   clk, clk1
+   );
+   input clk;
+   input clk1;
+
+   output int cnt0;
+   output int cnt1;
+
+   always @ (posedge clk) cnt0 <= cnt0 + 1;
+   always @ (posedge clk1) cnt1 <= cnt1 + 1;
+
+   final if (cnt0 == 0) $stop;
+   final if (cnt1 != 0) $stop;
+
+   always_comb begin
+      if (cnt0==99) begin
+         $write("*-* All Finished *-*\n");
+         $finish;
+      end
+   end
+endmodule