verilator/include/verilated_fst_c.cpp
Geza Lore dc5c259069
Improve tracing performance. (#2257)
* Improve tracing performance.

Various tactics used to improve performance of both VCD and FST tracing:
- Both: Change tracing functions to templates to take variable widths as
  template parameters. For VCD, subsequently specialize these to the
  values used by Verilator. This avoids redundant instructions and hard
  to predict branches.
- Both: Check for value changes via direct pointer access into the
  previous signal value buffer. This eliminates a lot of simple pointer
  arithmetic instructions form the tracing code.
- Both: Verilator provides clean input, no need to mask out used bits.
- VCD: pre-compute identifier codes and use memory copy instead of
  re-computing them every time a code is emitted. This saves a lot of
  instructions and hard to predict branches. The added D-cache misses
  are cheaper than the removed branches/instructions.
- VCD: re-write the routines emitting the changes to be more efficient.
- FST: Use previous signal value buffer the same way as the VCD tracing
  code, and only call the FST API when a change is detected.

Performance as measured on SweRV EH1, with the pre-canned CoreMark
benchmark running from DCCM/ICCM, clang 6.0.0, Intel i7-3770 @ 3.40GHz,
and IO to ramdisk:

            +--------------+---------------+----------------------+
            | VCD          | FST           | FST separate thread  |
            | (--trace)    | (--trace-fst) | (--trace-fst-thread) |
------------+-----------------------------------------------------+
Before      |  30.2 s      | 121.1 s       |  69.8 s              |
============+==============+===============+======================+
After       |  24.7 s      |  45.7 s       |  32.4 s              |
------------+--------------+---------------+----------------------+
Speedup     |    22 %      |   256 %       |   215 %              |
------------+--------------+---------------+----------------------+
Rel. to VCD |     1 x      |  1.85 x       |  1.31 x              |
------------+--------------+---------------+----------------------+

In addition, FST trace size for the above reduced by 48%.
2020-04-14 00:13:10 +01:00

249 lines
8.5 KiB
C++

// -*- mode: C++; c-file-style: "cc-mode" -*-
//=============================================================================
//
// THIS MODULE IS PUBLICLY LICENSED
//
// Copyright 2001-2020 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
//
//=============================================================================
///
/// \file
/// \brief C++ Tracing in FST Format
///
//=============================================================================
// SPDIFF_OFF
// clang-format off
#define __STDC_LIMIT_MACROS // UINT64_MAX
#include "verilatedos.h"
#include "verilated.h"
#include "verilated_fst_c.h"
// GTKWave configuration
#ifdef VL_TRACE_THREADED
# define HAVE_LIBPTHREAD
# define FST_WRITER_PARALLEL
#endif
// Include the GTKWave implementation directly
#define FST_CONFIG_INCLUDE "fst_config.h"
#include "gtkwave/fastlz.c"
#include "gtkwave/fstapi.c"
#include "gtkwave/lz4.c"
#include <algorithm>
#include <cerrno>
#include <ctime>
#include <fcntl.h>
#include <iterator>
#include <sstream>
#include <sys/stat.h>
#if defined(_WIN32) && !defined(__MINGW32__) && !defined(__CYGWIN__)
# include <io.h>
#else
# include <stdint.h>
# include <unistd.h>
#endif
// clang-format on
//=============================================================================
class VerilatedFstCallInfo {
protected:
friend class VerilatedFst;
VerilatedFstCallback_t m_initcb; ///< Initialization Callback function
VerilatedFstCallback_t m_fullcb; ///< Full Dumping Callback function
VerilatedFstCallback_t m_changecb; ///< Incremental Dumping Callback function
void* m_userthis; ///< Fake "this" for caller
vluint32_t m_code; ///< Starting code number
// CONSTRUCTORS
VerilatedFstCallInfo(VerilatedFstCallback_t icb, VerilatedFstCallback_t fcb,
VerilatedFstCallback_t changecb, void* ut)
: m_initcb(icb)
, m_fullcb(fcb)
, m_changecb(changecb)
, m_userthis(ut)
, m_code(1) {}
~VerilatedFstCallInfo() {}
};
//=============================================================================
// VerilatedFst
VerilatedFst::VerilatedFst(void* fst)
: m_fst(fst)
, m_fullDump(true)
, m_minNextDumpTime(0)
, m_nextCode(1)
, m_scopeEscape('.')
, m_symbolp(NULL)
, m_sigs_oldvalp(NULL) {
m_valueStrBuffer.reserve(64 + 1); // Need enough room for quad
}
VerilatedFst::~VerilatedFst() {
if (m_fst) fstWriterClose(m_fst);
if (m_symbolp) VL_DO_CLEAR(delete[] m_symbolp, m_symbolp = NULL);
if (m_sigs_oldvalp) VL_DO_CLEAR(delete[] m_sigs_oldvalp, m_sigs_oldvalp = NULL);
}
void VerilatedFst::open(const char* filename) VL_MT_UNSAFE {
m_assertOne.check();
m_fst = fstWriterCreate(filename, 1);
fstWriterSetPackType(m_fst, FST_WR_PT_LZ4);
#ifdef VL_TRACE_THREADED
fstWriterSetParallelMode(m_fst, 1);
#endif
m_curScope.clear();
m_nextCode = 1;
for (vluint32_t ent = 0; ent < m_callbacks.size(); ++ent) {
VerilatedFstCallInfo* cip = m_callbacks[ent];
cip->m_code = m_nextCode;
// Initialize; callbacks will call decl* which update m_nextCode
(cip->m_initcb)(this, cip->m_userthis, cip->m_code);
}
// Clear the scope stack
std::list<std::string>::iterator it = m_curScope.begin();
while (it != m_curScope.end()) {
fstWriterSetUpscope(m_fst);
it = m_curScope.erase(it);
}
// convert m_code2symbol into an array for fast lookup
if (!m_symbolp) {
m_symbolp = new fstHandle[m_nextCode + 10];
for (Code2SymbolType::iterator it = m_code2symbol.begin(); it != m_code2symbol.end();
++it) {
m_symbolp[it->first] = it->second;
}
}
m_code2symbol.clear();
// Allocate space now we know the number of codes
if (!m_sigs_oldvalp) m_sigs_oldvalp = new vluint32_t[m_nextCode + 10];
}
void VerilatedFst::module(const std::string& name) { m_module = name; }
//=============================================================================
// Decl
void VerilatedFst::declDTypeEnum(int dtypenum, const char* name, vluint32_t elements,
unsigned int minValbits, const char** itemNamesp,
const char** itemValuesp) {
fstEnumHandle enumNum
= fstWriterCreateEnumTable(m_fst, name, elements, minValbits, itemNamesp, itemValuesp);
m_local2fstdtype[dtypenum] = enumNum;
}
void VerilatedFst::declSymbol(vluint32_t code, const char* name, int dtypenum, fstVarDir vardir,
fstVarType vartype, bool array, int arraynum, vluint32_t len,
vluint32_t bits) {
// Make sure deduplicate tracking increments for future declarations
int codesNeeded = 1 + int(bits / 32);
// Not supported: if (tri) codesNeeded *= 2; // Space in change array for __en signals
m_nextCode = std::max(m_nextCode, code + codesNeeded);
std::pair<Code2SymbolType::iterator, bool> p
= m_code2symbol.insert(std::make_pair(code, static_cast<fstHandle>(NULL)));
std::istringstream nameiss(name);
std::istream_iterator<std::string> beg(nameiss), end;
std::list<std::string> tokens(beg, end); // Split name
std::string symbol_name(tokens.back());
tokens.pop_back(); // Remove symbol name from hierarchy
tokens.insert(tokens.begin(), m_module); // Add current module to the hierarchy
// Find point where current and new scope diverge
std::list<std::string>::iterator cur_it = m_curScope.begin();
std::list<std::string>::iterator new_it = tokens.begin();
while (cur_it != m_curScope.end() && new_it != tokens.end()) {
if (*cur_it != *new_it) break;
++cur_it;
++new_it;
}
// Go back to the common point
while (cur_it != m_curScope.end()) {
fstWriterSetUpscope(m_fst);
cur_it = m_curScope.erase(cur_it);
}
// Follow the hierarchy of the new variable from the common scope point
while (new_it != tokens.end()) {
fstWriterSetScope(m_fst, FST_ST_VCD_SCOPE, new_it->c_str(), NULL);
m_curScope.push_back(*new_it);
new_it = tokens.erase(new_it);
}
std::stringstream name_ss;
name_ss << symbol_name;
if (array) name_ss << "(" << arraynum << ")";
std::string name_str = name_ss.str();
if (dtypenum > 0) {
fstEnumHandle enumNum = m_local2fstdtype[dtypenum];
fstWriterEmitEnumTableRef(m_fst, enumNum);
}
if (p.second) { // New
p.first->second = fstWriterCreateVar(m_fst, vartype, vardir, len, name_str.c_str(), 0);
assert(p.first->second);
} else { // Alias
fstWriterCreateVar(m_fst, vartype, vardir, len, name_str.c_str(), p.first->second);
}
}
//=============================================================================
// Callbacks
void VerilatedFst::addCallback(VerilatedFstCallback_t initcb, VerilatedFstCallback_t fullcb,
VerilatedFstCallback_t changecb, void* userthis) VL_MT_UNSAFE_ONE {
m_assertOne.check();
if (VL_UNLIKELY(isOpen())) {
std::string msg = (std::string("Internal: ") + __FILE__ + "::" + __FUNCTION__
+ " called with already open file");
VL_FATAL_MT(__FILE__, __LINE__, "", msg.c_str());
}
VerilatedFstCallInfo* cip = new VerilatedFstCallInfo(initcb, fullcb, changecb, userthis);
m_callbacks.push_back(cip);
}
//=============================================================================
// Dumping
void VerilatedFst::dump(vluint64_t timeui) {
if (!isOpen()) return;
if (timeui < m_minNextDumpTime) {
VL_PRINTF_MT("%%Warning: previous dump at t=%" VL_PRI64 "u, requesting t=%" VL_PRI64 "u\n",
m_minNextDumpTime - 1, timeui);
return;
}
m_minNextDumpTime = timeui + 1;
if (VL_UNLIKELY(m_fullDump)) {
m_fullDump = false; // No more need for next dump to be full
for (vluint32_t ent = 0; ent < m_callbacks.size(); ++ent) {
VerilatedFstCallInfo* cip = m_callbacks[ent];
(cip->m_fullcb)(this, cip->m_userthis, cip->m_code);
}
return;
}
fstWriterEmitTimeChange(m_fst, timeui);
for (vluint32_t ent = 0; ent < m_callbacks.size(); ++ent) {
VerilatedFstCallInfo* cip = m_callbacks[ent];
(cip->m_changecb)(this, cip->m_userthis, cip->m_code);
}
}
//********************************************************************
// Local Variables:
// End: