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ece25a45d4
Aggressive wire localization and inlining is necessary for CXXRTL to
achieve high performance. However, that comes with a cost: reduced
debug information coverage. Previously, as a workaround, the `-Og`
option could have been used to guarantee complete coverage, at a cost
of a significant performance penalty.
This commit introduces debug information outlining. The main eval()
function is compiled with the user-specified optimization settings.
In tandem, an auxiliary debug_eval() function, compiled from the same
netlist, can be used to reconstruct the values of localized/inlined
signals on demand. To the extent that it is possible, debug_eval()
reuses the results of computations performed by eval(), only filling
in the missing values.
Benchmarking a representative design (Minerva SoC SRAM) shows that:
* Switching from `-O4`/`-Og` to `-O6` reduces runtime by ~40%.
* Switching from `-g1` to `-g2`, both used with `-O6`, increases
compile time by ~25%.
* Although `-g2` increases the resident size of generated modules,
this has no effect on runtime.
Because the impact of `-g2` is minimal and the benefits of having
unconditional 100% debug information coverage (and the performance
improvement as well) are major, this commit removes `-Og` and changes
the defaults to `-O6 -g2`.
We'll have our cake and eat it too!
93 lines
2.9 KiB
C++
93 lines
2.9 KiB
C++
/*
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* yosys -- Yosys Open SYnthesis Suite
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*
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* Copyright (C) 2020 whitequark <whitequark@whitequark.org>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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// This file is a part of the CXXRTL C API. It should be used together with `cxxrtl_capi.h`.
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#include <backends/cxxrtl/cxxrtl.h>
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#include <backends/cxxrtl/cxxrtl_capi.h>
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struct _cxxrtl_handle {
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std::unique_ptr<cxxrtl::module> module;
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cxxrtl::debug_items objects;
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};
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// Private function for use by other units of the C API.
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const cxxrtl::debug_items &cxxrtl_debug_items_from_handle(cxxrtl_handle handle) {
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return handle->objects;
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}
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cxxrtl_handle cxxrtl_create(cxxrtl_toplevel design) {
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return cxxrtl_create_at(design, "");
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}
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cxxrtl_handle cxxrtl_create_at(cxxrtl_toplevel design, const char *root) {
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std::string path = root;
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if (!path.empty()) {
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// module::debug_info() accepts either an empty path, or a path ending in space to simplify
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// the logic in generated code. While this is sketchy at best to expose in the C++ API, this
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// would be a lot worse in the C API, so don't expose it here.
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assert(path.back() != ' ');
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path += ' ';
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}
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cxxrtl_handle handle = new _cxxrtl_handle;
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handle->module = std::move(design->module);
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handle->module->debug_info(handle->objects, path);
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delete design;
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return handle;
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}
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void cxxrtl_destroy(cxxrtl_handle handle) {
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delete handle;
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}
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void cxxrtl_reset(cxxrtl_handle handle) {
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handle->module->reset();
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}
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int cxxrtl_eval(cxxrtl_handle handle) {
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return handle->module->eval();
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}
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int cxxrtl_commit(cxxrtl_handle handle) {
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return handle->module->commit();
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}
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size_t cxxrtl_step(cxxrtl_handle handle) {
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return handle->module->step();
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}
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struct cxxrtl_object *cxxrtl_get_parts(cxxrtl_handle handle, const char *name, size_t *parts) {
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auto it = handle->objects.table.find(name);
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if (it == handle->objects.table.end())
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return nullptr;
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*parts = it->second.size();
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return static_cast<cxxrtl_object*>(&it->second[0]);
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}
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void cxxrtl_enum(cxxrtl_handle handle, void *data,
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void (*callback)(void *data, const char *name,
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cxxrtl_object *object, size_t parts)) {
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for (auto &it : handle->objects.table)
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callback(data, it.first.c_str(), static_cast<cxxrtl_object*>(&it.second[0]), it.second.size());
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}
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void cxxrtl_outline_eval(cxxrtl_outline outline) {
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outline->eval();
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}
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