Fix trace overflow on huge arrays, bug834.

Changes

@@ -15,6 +15,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ****  Fix not tracing modules following primitives, bug837. [Jie Xu]
 
+****  Fix trace overflow on huge arrays, bug834. [Geoff Barrett]
+
 
 * Verilator 3.864 2014-09-21
 

include/verilated_vcd_c.cpp

@@ -261,6 +261,20 @@ void VerilatedVcd::printTime (vluint64_t timeui) {
     printQuad(timeui);
 }
 
+void VerilatedVcd::bufferResize(vluint64_t minsize) {
+    // minsize is size of largest write.  We buffer at least 8 times as much data,
+    // writing when we are 3/4 full (with thus 2*minsize remaining free)
+    if (VL_UNLIKELY(minsize > m_wrChunkSize)) {
+	char* oldbufp = m_wrBufp;
+	m_wrChunkSize = minsize*2;
+	m_wrBufp = new char [m_wrChunkSize * 8];
+	memcpy(m_wrBufp, oldbufp, m_writep - oldbufp);
+        m_writep = m_wrBufp + (m_writep - oldbufp);
+	m_wrFlushp = m_wrBufp + m_wrChunkSize * 6;
+	delete oldbufp; oldbufp=NULL;
+    }
+}
+
 void VerilatedVcd::bufferFlush () {
     // We add output data to m_writep.
     // When it gets nearly full we dump it using this routine which calls write()
@@ -444,6 +458,9 @@ void VerilatedVcd::declare (vluint32_t code, const char* name, const char* wirep
 	m_sigs.reserve(m_nextCode*2);	// Power-of-2 allocation speeds things up
     }
 
+    // Make sure write buffer is large enough (one character per bit), plus header
+    bufferResize(bits+1024);
+
     // Save declaration info
     VerilatedVcdSig sig = VerilatedVcdSig(code, bits);
     m_sigs.push_back(sig);
@@ -522,7 +539,7 @@ void VerilatedVcd::declDouble   (vluint32_t code, const char* name, int arraynum
 
 void VerilatedVcd::fullDouble (vluint32_t code, const double newval) {
     (*((double*)&m_sigs_oldvalp[code])) = newval;
-    // Buffer can't overflow; we have at least bufferInsertSize() bytes (>>>16 bytes)
+    // Buffer can't overflow before sprintf; we sized during declaration
     sprintf(m_writep, "r%.16g", newval);
     m_writep += strlen(m_writep);
     *m_writep++=' '; printCode(code); *m_writep++='\n';
@@ -530,7 +547,7 @@ void VerilatedVcd::fullDouble (vluint32_t code, const double newval) {
 }
 void VerilatedVcd::fullFloat (vluint32_t code, const float newval) {
     (*((float*)&m_sigs_oldvalp[code])) = newval;
-    // Buffer can't overflow; we have at least bufferInsertSize() bytes (>>>16 bytes)
+    // Buffer can't overflow before sprintf; we sized during declaration
     sprintf(m_writep, "r%.16g", (double)newval);
     m_writep += strlen(m_writep);
     *m_writep++=' '; printCode(code); *m_writep++='\n';

include/verilated_vcd_c.h

@@ -77,7 +77,9 @@ private:
     vluint64_t		m_timeLastDump;	///< Last time we did a dump
 
     char*		m_wrBufp;	///< Output buffer
+    char*		m_wrFlushp;	///< Output buffer flush trigger location
     char*		m_writep;	///< Write pointer into output buffer
+    vluint64_t		m_wrChunkSize;	///< Output buffer size
     vluint64_t		m_wroteBytes;	///< Number of bytes written to this file
 
     vluint32_t*			m_sigs_oldvalp;	///< Pointer to old signal values
@@ -87,13 +89,12 @@ private:
     NameMap*			m_namemapp;	///< List of names for the header
     static vector<VerilatedVcd*>	s_vcdVecp;	///< List of all created traces
 
-    inline static size_t bufferSize() { return 256*1024; }  // See below for slack calculation
-    inline static size_t bufferInsertSize() { return 16*1024; }
+    void bufferResize(vluint64_t minsize);
     void bufferFlush();
-    void bufferCheck() {
+    inline void bufferCheck() {
 	// Flush the write buffer if there's not enough space left for new information
 	// We only call this once per vector, so we need enough slop for a very wide "b###" line
-	if (VL_UNLIKELY(m_writep > (m_wrBufp+(bufferSize()-bufferInsertSize())))) {
+	if (VL_UNLIKELY(m_writep > m_wrFlushp)) {
 	    bufferFlush();
 	}
     }
@@ -135,17 +136,19 @@ protected:
 public:
     // CREATORS
     VerilatedVcd () : m_isOpen(false), m_rolloverMB(0), m_modDepth(0), m_nextCode(1) {
-	m_wrBufp = new char [bufferSize()];
-	m_writep = m_wrBufp;
 	m_namemapp = NULL;
 	m_timeRes = m_timeUnit = 1e-9;
 	m_timeLastDump = 0;
 	m_sigs_oldvalp = NULL;
 	m_evcd = false;
 	m_scopeEscape = '.';  // Backward compatibility
-	m_wroteBytes = 0;
 	m_fd = 0;
 	m_fullDump = true;
+	m_wrChunkSize = 8*1024;
+	m_wrBufp = new char [m_wrChunkSize*8];
+	m_wrFlushp = m_wrBufp + m_wrChunkSize * 6;
+	m_writep = m_wrBufp;
+	m_wroteBytes = 0;
     }
     ~VerilatedVcd();
 

test_regress/t/t_trace_array.pl

@@ -0,0 +1,21 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003-2009 by Wilson Snyder. This program is free software; you can
+# redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+
+compile (
+    verilator_flags2 => ['--cc --trace --trace-structs'],
+    );
+
+execute (
+    check_finished=>1,
+    );
+
+file_grep     ("$Self->{obj_dir}/simx.vcd", qr/\$enddefinitions/x);
+
+ok(1);
+1;

test_regress/t/t_trace_array.v

@@ -0,0 +1,26 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2014 by Wilson Snyder.
+
+module t (clk);
+   input clk;
+   integer 	cyc=0;
+
+   // Trace would overflow at 256KB which is 256 kb dump, 16 kb in a chunk
+
+   typedef struct packed {
+      logic [1024*1024:0] d;
+   } s1_t; // 128 b
+
+   s1_t biggie;
+
+   always @ (posedge clk) begin
+      cyc <= cyc + 1;
+      biggie [ cyc +: 32 ] <= 32'hfeedface;
+      if (cyc == 5) begin
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
+   end
+endmodule