Add --autoflush option

Changes

@@ -8,6 +8,8 @@ indicates the contributor was also the author of the fix; Thanks!
 **   Add --x-assign=fast option, and make it the default.
      This chooses performance over reset debugging.  See the manual.
 
+**   Add --autoflush, for flushing streams after $display.  [Steve Tong]
+
 ***  Add $feof, $fgetc, $fgets, $fflush, $fscanf, $sscanf. [Holger Waechtler]
 
 ***  Add $stime. [Holger Waechtler]

bin/verilator

@@ -177,6 +177,7 @@ descriptions in the next sections for more information.
     {file.c/cc/cpp}             Optional C++ files to link in
 
     --assert                    Enable all assertions
+    --autoflush                 Flush streams after all $displays
     --bin <filename>            Override Verilator binary
     --cc                        Create C++ output
     --compiler <compiler-name>  Tune for specified C++ compiler
@@ -254,6 +255,12 @@ desired, but other assertions are, use --assert --nopsl.)
 
 See also --x-assign; setting "--x-assign unique" may be desirable.
 
+=item --autoflush
+
+After every $display or $fdisplay, flush the output stream.  This insures
+that messages will appear immediately but may reduce performance.  Defaults
+off, which will buffer output as provided by the normal C stdio calls.
+
 =item --bin I<filename>
 
 Rarely needed.  Override the default filename for Verilator itself.  When a

src/V3EmitC.cpp

@@ -306,11 +306,15 @@ public:
 	puts("=0; }\n");
     }
     virtual void visit(AstFFlush* nodep, AstNUser*) {
-	puts("if (");
-	nodep->filep()->iterateAndNext(*this);
-	puts(") { fflush (VL_CVT_Q_FP(");
-	nodep->filep()->iterateAndNext(*this);
-	puts(")); ");
+	if (!nodep->filep()) {
+	    puts("fflush (stdout);\n");
+	} else {
+	    puts("if (");
+	    nodep->filep()->iterateAndNext(*this);
+	    puts(") { fflush (VL_CVT_Q_FP(");
+	    nodep->filep()->iterateAndNext(*this);
+	    puts(")); }\n");
+	}
     }
     virtual void visit(AstWhile* nodep, AstNUser*) {
 	nodep->precondsp()->iterateAndNext(*this);

src/V3LinkResolve.cpp

@@ -368,7 +368,9 @@ private:
     }
     virtual void visit(AstFFlush* nodep, AstNUser*) {
 	nodep->iterateChildren(*this);
-	expectDescriptor(nodep, nodep->filep()->castNodeVarRef());
+	if (nodep->filep()) {
+	    expectDescriptor(nodep, nodep->filep()->castNodeVarRef());
+	}
     }
     virtual void visit(AstFGetC* nodep, AstNUser*) {
 	nodep->iterateChildren(*this);

src/V3Options.cpp

@@ -563,6 +563,7 @@ void V3Options::parseOptsList(FileLine* fl, int argc, char** argv) {
 	    else if ( onoff   (sw, "-MMD", flag/*ref*/) )	{ m_makeDepend = flag; }
 	    else if ( onoff   (sw, "-MP", flag/*ref*/) )	{ m_makePhony = flag; }
 	    else if ( onoff   (sw, "-assert", flag/*ref*/) )	{ m_assert = flag; m_psl = flag; }
+	    else if ( onoff   (sw, "-autoflush", flag/*ref*/) )	{ m_autoflush = flag; }
 	    else if ( !strcmp (sw, "-cc") )			{ m_outFormatOk = true; m_systemC = false; m_systemPerl = false; }
 	    else if ( onoff   (sw, "-coverage", flag/*ref*/) )	{ coverage(flag); }
 	    else if ( onoff   (sw, "-coverage-line", flag/*ref*/) ){ m_coverageLine = flag; }
@@ -793,6 +794,7 @@ void V3Options::parseOptsFile(FileLine* fl, const string& filename) {
 V3Options::V3Options() {
     m_impp = new V3OptionsImp;
 
+    m_autoflush = false;
     m_coverageLine = false;
     m_coverageUser = false;
     m_debugCheck = false;

src/V3Options.h

@@ -86,6 +86,7 @@ class V3Options {
     bool	m_makeDepend;	// main switch: -MMD
     bool	m_makePhony;	// main switch: -MP
     bool	m_assert;	// main switch: --assert
+    bool	m_autoflush;	// main switch: --autoflush
     bool	m_coverageLine;	// main switch: --coverage-block
     bool	m_coverageUser;	// main switch: --coverage-func
     bool	m_debugCheck;	// main switch: --debug-check
@@ -182,6 +183,7 @@ class V3Options {
     bool skipIdentical() const { return m_skipIdentical; }
     bool stats() const { return m_stats; }
     bool assertOn() const { return m_assert; }  // assertOn as "assert" may be defined
+    bool autoflush() const { return m_autoflush; }
     bool coverage() const { return m_coverageUser || m_coverageLine; }
     bool coverageLine() const { return m_coverageLine; }
     bool coverageUser() const { return m_coverageUser; }

src/V3Premit.cpp

@@ -23,6 +23,9 @@
 //	For each wide OP, make a a temporary variable with the wide value
 //	For each deep expression, assign expression to temporary.
 //
+// Each display (independant transformation; here as Premit is a good point)
+//	If autoflush, insert a flush
+//
 //*************************************************************************
 
 #include "config_build.h"
@@ -264,6 +267,26 @@ private:
 	checkNode(nodep);
     }
 
+    // Autoflush
+    virtual void visit(AstDisplay* nodep, AstNUser* vup) {
+	startStatement(nodep);
+	nodep->iterateChildren(*this);
+	m_stmtp = NULL;
+	if (v3Global.opt.autoflush()) {
+	    AstNode* searchp = nodep->nextp();
+	    while (searchp && searchp->castComment()) searchp = searchp->nextp();
+	    if (searchp
+		&& searchp->castDisplay()
+		&& nodep->filep()->sameTree(searchp->castDisplay()->filep())) {
+		// There's another display next; we can just wait to flush
+	    } else {
+		UINFO(4,"Autoflush "<<nodep<<endl);
+		nodep->addNextHere(new AstFFlush(nodep->fileline(),
+						 nodep->filep()->cloneTree(true)));
+	    }
+	}
+    }
+
     //--------------------
     // Default: Just iterate
     virtual void visit(AstVar* nodep, AstNUser*) {}	// Don't hit varrefs under vars

src/V3Width.cpp

@@ -586,8 +586,10 @@ private:
 	widthCheck(nodep,"file_descriptor (see docs)",nodep->filep(),64,64);
     }
     virtual void visit(AstFFlush* nodep, AstNUser*) {
-	nodep->filep()->iterateAndNext(*this,WidthVP(64,64,BOTH).p());
-	widthCheck(nodep,"file_descriptor (see docs)",nodep->filep(),64,64);
+	if (nodep->filep()) {
+	    nodep->filep()->iterateAndNext(*this,WidthVP(64,64,BOTH).p());
+	    widthCheck(nodep,"file_descriptor (see docs)",nodep->filep(),64,64);
+	}
     }
     virtual void visit(AstFGetC* nodep, AstNUser* vup) {
 	nodep->filep()->iterateAndNext(*this,WidthVP(64,64,BOTH).p());

test_regress/t/t_sys_file_autoflush.pl

@@ -0,0 +1,22 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("./driver.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
+# General Public License or the Perl Artistic License.
+
+top_filename("t/t_sys_file_basic.v");
+
+compile (
+	 v_flags2 => ['+incdir+../include',
+		      '+define+AUTOFLUSH'],
+	 verilator_flags2 => ['--autoflush'],
+	 );
+
+execute (
+	 check_finished=>1,
+     );
+
+ok(1);
+1;

test_regress/t/t_sys_file_basic.pl

@@ -9,6 +9,7 @@ if (!$::Driver) { use FindBin; exec("./driver.pl", @ARGV, $0); die; }
 unlink("obj_dir/t_sys_file_basic_test.log");
 
 compile (
+	 v_flags2 => ['+incdir+../include'],
 	 );
 
 execute (

test_regress/t/t_sys_file_basic.v

@@ -28,7 +28,13 @@ module t;
       if (!$feof(file)) $stop;
 `endif
 
-      file = $fopen("obj_dir/t_sys_file_basic_test.log","w");	// The "w" is required so we get a FD not a MFD
+`ifdef AUTOFLUSH
+      // The "w" is required so we get a FD not a MFD
+      file = $fopen("obj_dir/t_sys_file_autoflush.log","w");
+`else
+      // The "w" is required so we get a FD not a MFD
+      file = $fopen("obj_dir/t_sys_file_basic_test.log","w");
+`endif
       if ($feof(file)) $stop;
 
       $fdisplay(file, "[%0t] hello v=%x", $time, 32'h12345667);