From c1665818b955c4730896315a580d0bbaffb3d95a Mon Sep 17 00:00:00 2001
From: Geza Lore <gezalore@gmail.com>
Date: Fri, 24 Apr 2020 03:09:26 +0100
Subject: [PATCH] Fix missing flush with threaded VCD tracing. (#2282)

VerilatedVcdC::openNext() failed to flush the tracing thread before
opening the next output file, which caused t_trace_cat.pl to fail
with --vltmt on occasion.
---
 include/verilated_vcd_c.cpp | 12 ++++++------
 include/verilated_vcd_c.h   |  2 +-
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/verilated_vcd_c.cpp b/include/verilated_vcd_c.cpp
index c5ad6f7bb..9f5befff3 100644
--- a/include/verilated_vcd_c.cpp
+++ b/include/verilated_vcd_c.cpp
@@ -294,18 +294,17 @@ void VerilatedVcd::close() {
     // This function is on the flush() call path
     m_assertOne.check();
     if (!isOpen()) return;
-    VerilatedTrace<VerilatedVcd>::close();
     if (m_evcd) {
         printStr("$vcdclose ");
         printQuad(timeLastDump());
         printStr(" $end\n");
     }
     closePrev();
-}
-
-void VerilatedVcd::flush() {
-    VerilatedTrace<VerilatedVcd>::flush();
-    bufferFlush();
+    // closePrev() already called VerilatedTrace<VerilatedVcd>::flush() via
+    // bufferFlush(), and there were no opportunities to enqueue further
+    // buffers as this close() is running on the main thread the same as dump()
+    // so just shutting down the trace thread will suffice.
+    VerilatedTrace<VerilatedVcd>::close();
 }
 
 void VerilatedVcd::printStr(const char* str) {
@@ -343,6 +342,7 @@ void VerilatedVcd::bufferFlush() VL_MT_UNSAFE_ONE {
     // This is much faster than using buffered I/O
     m_assertOne.check();
     if (VL_UNLIKELY(!isOpen())) return;
+    VerilatedTrace<VerilatedVcd>::flush();
     char* wp = m_wrBufp;
     while (true) {
         ssize_t remaining = (m_writep - wp);
diff --git a/include/verilated_vcd_c.h b/include/verilated_vcd_c.h
index e9838c15b..0ee8084c8 100644
--- a/include/verilated_vcd_c.h
+++ b/include/verilated_vcd_c.h
@@ -149,7 +149,7 @@ public:
     /// Close the file
     void close() VL_MT_UNSAFE_ONE;
     /// Flush any remaining data to this file
-    void flush() VL_MT_UNSAFE_ONE;
+    void flush() VL_MT_UNSAFE_ONE { bufferFlush(); }
     /// Is file open?
     bool isOpen() const { return m_isOpen; }