<div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif">Yes, it's a good idea to add cfe-dev.</div><div class="gmail_default" style="font-family:verdana,sans-serif">It is totally possible that I overlooked something and clang can help with this kind of superficial parsing. <br></div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif">As far as I can see even clang-format does it's own parsing (UnwrappedLineParser.cpp) and clang-format has very similar need of roughly understanding of code without knowing any context.</div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div>> are you certain that clang's parser would be unacceptably slow?<div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif">I don't have any perf numbers to back it up, but it does look like a lot of clang infrastructure needs to be set up before actual parsing begins. (see lldb_private::<wbr>ClangExpressionParser). It's not important though, as at this stage I don't see how we can reuse clang at all.</div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Mar 15, 2017 at 5:03 PM, Zachary Turner <span dir="ltr"><<a href="mailto:zturner@google.com" target="_blank">zturner@google.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">If there is any way to re-use clang parser for this, it would be wonderful. Even if it means adding support to clang for whatever you need in order to make it possible. You mention performance, are you certain that clang's parser would be unacceptably slow?<div><br></div><div>+cfe-dev as they may have some more input on what it would take to extend clang to make this possible.<br><br><div class="gmail_quote"><div><div class="h5"><div dir="ltr">On Wed, Mar 15, 2017 at 4:48 PM Eugene Zemtsov via lldb-dev <<a href="mailto:lldb-dev@lists.llvm.org" target="_blank">lldb-dev@lists.llvm.org</a>> wrote:<br></div></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr" class="m_1554989480439670304gmail_msg"><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Hi, Everyone.</font><br class="m_1554989480439670304gmail_msg"></div><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></font></div><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Current implementation of CPlusPlusLanguage::MethodName:<wbr>:Parse() doesn't cover full extent of possible function declarations, </font></div><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">or even declarations returned by abi::__cxa_demangle. </font></div><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></font></div><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Consider this code:</font></div><div class="gmail_default m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">------------------------------<wbr>--------------------<br class="m_1554989480439670304gmail_msg"></font></div><div class="gmail_default m_1554989480439670304gmail_msg"><pre style="font-size:11.726px;white-space:pre-wrap;max-width:80em;padding-left:0.7em;color:rgb(0,0,0)" class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">#include <stdio.h>
#include <functional>
#include <vector>
void func() {
printf("func() was called\n");
}
struct Class
{
Class() {
printf("ctor was called\n");
}
Class(const Class& c) {
printf("copy ctor was called\n");
}
~Class() {
printf("dtor was called\n");
}
};
int main() {
std::function<void()> f = func;
f();
Class c;
std::vector<Class> v;
v.push_back(c);
return 0;
}
</font></pre><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">------------------------------<wbr>--------------------<br class="m_1554989480439670304gmail_msg"></font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">When compiled It has at least two symbols that currently cannot be correctly parsed by MethodName::Parse() .</font></div><div class="m_1554989480439670304gmail_msg"><pre style="font-size:11.726px;white-space:pre-wrap;max-width:80em;padding-left:0.7em;color:rgb(0,0,0)" class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">void std::vector<Class, std::allocator<Class> >::_M_emplace_back_aux<Class const&>(Class const&)
void (* const&std::_Any_data::_M_<wbr>access<void (*)()>() const)() - a template function that returns a reference to a function pointer.
</font></pre></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">It causes incorrect behavior in avoid-stepping and sometimes messes printing of thread backtrace.</font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">I would like to solve this issue, but current implementation of method name parsing doesn't seem sustainable. </font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Clever substrings and regexs are fine for trivial cases, but they become a nightmare once we consider more complex cases.</font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">That's why I'd like to have code that follows some kind of grammar describing function declarations.</font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">As I see it, choices for new implementation of </font><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">MethodName::Parse() </span><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">are</span></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">1. Reuse clang parsing code.</font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">2. Parser generated by bison.</font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">3. Handwritten recursive descent parser.</font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">I looked at the option #1, at it appears to be impossible to reuse clang parser for this kind of zero-context parsing. </font></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Especially given that we care about performance of this code. </font><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">Clang C++ lexer on the other hand can be reused.</span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">Option #2. Using bison is tempting, but it would require introduction of new compile time dependency. </span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">That might be especially inconvenient on Windows.</span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">That's why I think option #3 is the way to go. Recursive descent parser that reuses a C++ lexer from clang. </span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></span></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">LLDB doesn't need to parse everything (</span><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg">e.g. we don't care about details of function arguments), but it needs to be able to handle tricky return types and base names.</span></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Eventually new implementation should be able to parse signature of every method generated by STL. </font></div><div class="m_1554989480439670304gmail_msg"><span style="font-family:verdana,sans-serif" class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></span></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Before starting implementation, I'd love to get some feedback. It might be that my overlooking something important.</font></div><div class="m_1554989480439670304gmail_msg"><br class="m_1554989480439670304gmail_msg"></div></div><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">-- <br class="m_1554989480439670304gmail_msg"></font></div><div class="m_1554989480439670304m_4700145260659919425gmail-m_-1339871576848199557gmail_signature m_1554989480439670304gmail_msg"><div dir="ltr" class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Thanks,</font><div class="m_1554989480439670304gmail_msg"><font face="verdana, sans-serif" class="m_1554989480439670304gmail_msg">Eugene Zemtsov.</font></div></div></div>
</div></div></div>
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</blockquote></div></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><font face="verdana, sans-serif">Thanks,</font><div><font face="verdana, sans-serif">Eugene Zemtsov.</font></div></div></div>
</div>