Add --no-debug-leak to reduce memory use under debug.

Changes

@@ -8,6 +8,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ***   Support calling system functions as tasks, bug1285. [Joel Holdsworth]
 
+***   Add --no-debug-leak to reduce memory use under debug. [John Coiner]
+
 ****  Fix GCC 8.0 issues, bug1273.
 
 ****  Fix pullup/pulldowns on bit selects, bug1274. [Rob Stoddard]

bin/verilator

@@ -278,6 +278,7 @@ descriptions in the next sections for more information.
      -D<var>[=<value>]          Set preprocessor define
     --debug                     Enable debugging
     --debug-check               Enable debugging assertions
+    --no-debug-leak             Disable leaking memory in --debug mode
     --debugi <level>            Enable debugging at a specified level
     --debugi-<srcfile> <level>  Enable debugging a source file at a level
     --default-language <lang>   Default language to parse
@@ -635,6 +636,18 @@ to C<--dump-treei 3>).
 Rarely needed.  Enable internal debugging assertion checks, without
 changing debug verbosity.  Enabled automatically when --debug specified.
 
+=item --no-debug-leak
+
+In --debug mode, by default Verilator intentionally leaks AstNode's
+instead of freeing them, so that each node pointer is unique in the
+resulting tree files and dot files.
+
+This option disables the leak. This may avoid out-of-memory errors
+when Verilating large models in --debug mode.
+
+Outside of --debug mode, AstNode's should never be leaked and this option
+has no effect.
+
 =item --debugi <level>
 
 =item --debugi-<srcfile> <level>

src/V3Ast.cpp

@@ -677,9 +677,17 @@ void AstNode::deleteNode() {
     this->m_op2p = (AstNode*)1;
     this->m_op3p = (AstNode*)1;
     this->m_op4p = (AstNode*)1;
+    if (
 #if !defined(VL_DEBUG) || defined(VL_LEAK_CHECKS)
-    delete this;	// Leak massively, so each pointer is unique and we can debug easier
+        1
+#else
+        !v3Global.opt.debugLeak()
 #endif
+        ) {
+        delete this;
+    }
+    // Else leak massively, so each pointer is unique
+    // and we can debug easier.
 }
 
 AstNode::~AstNode() {

src/V3Options.cpp

@@ -659,6 +659,7 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
 	    else if ( onoff   (sw, "-covsp", flag/*ref*/) )	{ }  // TBD
 	    else if ( !strcmp (sw, "-debug-abort") )		{ abort(); } // Undocumented, see also --debug-sigsegv
 	    else if ( onoff   (sw, "-debug-check", flag/*ref*/) ){ m_debugCheck = flag; }
+            else if ( onoff   (sw, "-debug-leak", flag/*ref*/) ){ m_debugLeak = flag; }
 	    else if ( !strcmp (sw, "-debug-sigsegv") )		{ throwSigsegv(); }  // Undocumented, see also --debug-abort
 	    else if ( !strcmp (sw, "-debug-fatalsrc") )		{ v3fatalSrc("--debug-fatal-src"); }  // Undocumented, see also --debug-abort
 	    else if ( onoff   (sw, "-decoration", flag/*ref*/) ) { m_decoration = flag; }
@@ -1218,6 +1219,7 @@ V3Options::V3Options() {
     m_coverageUnderscore = false;
     m_coverageUser = false;
     m_debugCheck = false;
+    m_debugLeak = true;
     m_decoration = true;
     m_exe = false;
     m_ignc = false;

src/V3Options.h

@@ -75,6 +75,7 @@ class V3Options {
     bool	m_coverageUnderscore;// main switch: --coverage-underscore
     bool	m_coverageUser;	// main switch: --coverage-func
     bool	m_debugCheck;	// main switch: --debug-check
+    bool        m_debugLeak;   // main switch: --debug-leak
     bool	m_decoration;	// main switch: --decoration
     bool	m_exe;		// main switch: --exe
     bool	m_ignc;		// main switch: --ignc
@@ -229,6 +230,7 @@ class V3Options {
     bool coverageUnderscore() const { return m_coverageUnderscore; }
     bool coverageUser() const { return m_coverageUser; }
     bool debugCheck() const { return m_debugCheck; }
+    bool debugLeak() const { return m_debugLeak; }
     bool decoration() const { return m_decoration; }
     bool exe() const { return m_exe; }
     bool trace() const { return m_trace; }

test_regress/t/t_flag_debug_noleak.pl

@@ -0,0 +1,20 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2008 by Wilson Snyder. This program is free software; you can
+# redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+
+$Self->{vlt} or $Self->skip("Verilator only test");
+
+compile (
+    v_flags2 => ["--debug --no-debug-leak"],
+    verilator_make_gcc => 0,
+    make_top_shell => 0,
+    make_main => 0,
+    );
+
+ok(1);
+1;

test_regress/t/t_flag_debug_noleak.v

@@ -0,0 +1,12 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2008 by Wilson Snyder.
+
+module t;
+   initial begin
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule
+