[cfe-dev] speed up debugging a static analysis checker?

Wed Oct 3 11:49:47 PDT 2018

That’s weird.
It takes about 1-2 seconds for me.

> On Oct 3, 2018, at 11:44 AM, Lou Wynn <lewisurn at gmail.com> wrote:
> 
> I copied my previous follow-up email below my signature, which you missed. Here's the full description.
> 
> The debugging commands are as follows.
> 
> llvm/debug-git$ lldb-6.0 -- bin/clang-8 -cc1 -analyze -analyzer-checker=alpha.unix.SimpleStream ../src-git/tools/clang/test/Analysis/simple-stream-checks.c
> (lldb) target create "bin/clang-8"
> Current executable set to 'bin/clang-8' (x86_64).
> (lldb) settings set -- target.run-args  "-cc1" "-analyze" "-analyzer-checker=alpha.unix.SimpleStream" "../src-git/tools/clang/test/Analysis/simple-stream-checks.c"
> 
> 
> (lldb) b SimpleStreamChecker.cpp:132
> Breakpoint 1: no locations (pending).
> WARNING:  Unable to resolve breakpoint to any actual locations.
> 

This is also weird. If lldb replies with “Unable to resolve breakpoint”, it means that, well, it could not resolve the breakpoint.
And yet it does stop at a breakpoint (much) later on.

Maybe try a simpler cmake invocation? You customize quite a few things, try just having no customizations at all.
You write that you have used gdb-add-index, but you should not have to use it.
> 
> 
> (lldb) run  <<<<<-------- takes about 21 seconds to hit the breakpoint
> Process 26355 launched: '/home/lu/work/git-repos/llvm/debug-git/bin/clang-8' (x86_64)
> 1 location added to breakpoint 1
> Process 26355 stopped
> * thread #1, name = 'clang-8', stop reason = breakpoint 1.1
>     frame #0: 0x00007fffec1f0188 libclangStaticAnalyzerCheckers.so.8svn`(anonymous namespace)::SimpleStreamChecker::checkPostCall(this=0x00000000002c0210, Call=0x0000000000335c80, C=0x00007fffffff83a8) const at SimpleStreamChecker.cpp:132
>    129      return;
>    130 
>    131    // Generate the next transition (an edge in the exploded graph).
> -> 132    ProgramStateRef State = C.getState();
>    133    State = State->set<StreamMap>(FileDesc, StreamState::getOpened());
>    134    C.addTransition(State);
>    135  }
> 
> 
> where clang-8 is built by using the following CMake configuration (and make clang):
> 
> cmake -G "Unix Makefiles" -DLLVM_OPTIMIZED_TABLEGEN=true -DCMAKE_BUILD_TYPE=Debug -DBUILD_SHARED_LIBS=ON ../src-git/ -DLLVM_USE_LINKER=lld-6.0 -DCMAKE_C_COMPILER=clang-6.0 -DCMAKE_CXX_COMPILER=clang++-6.0 -DLLVM_TARGETS_TO_BUILD=""
> 
> 
> 
> Love,
> Lou
> 
> On 09/28/2018 06:35 PM, Lou Wynn wrote:
>> My simplified test case file only contains one function, with others commented out.
>> 
>> I tried the RelWithDebInfo CMake build type, it slightly reduced the time to reach the first breakpoint from 21 to 16 seconds when I ran it with lldb command line. But when I debug clang in vscode, this configuration doesn't stop at the breakpoint (with the CodeLLDB extension). The Debug build stops at the breakpoint. Saving 4 seconds on command line is not useful because setting or canceling a breakpoint on the command line takes more time for me in the unfamiliar code base.
>> 
>> I already used gdb-add-index to the clang executable file.
>> 
>> Any other method might help?
>> 
>> How much time does it take you to stop at a breakpoint in a checker?
>> 
>> Love,
>> Lou
>> 
> 
> On 10/03/2018 11:12 AM, George Karpenkov wrote:
>> Hi Lou,
>> 
>> Somehow I haven’t seen your follow up email.
>> Can you describe a full reproducible example?
>> With an exact command line invocation, exact input file, and exact breakpoint line.
>> 
>> George
>> 
>>> On Sep 28, 2018, at 2:27 PM, George Karpenkov via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>>> 
>>> Hi Lou,
>>> 
>>> You probably want to only debug the analysis running on a function you are interested in.
>>> -Xclang -analyzer-display-progress
>>> shows what functions the analyzer is going through, and
>>> -Xclang -analyze-function “function-name”
>>> let’s you select the function (use the exact name copied from the previous list).
>>> 
>>> You can also try release+debuginfo configuration if the former is too slow.
>>> 20 seconds does sound excessive for a simple test file in any case though, so that is strange.
>>> 
>>>> On Sep 28, 2018, at 1:49 PM, Lou Wynn via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> I'm now having a question of how to speed up startup runs of a static analysis checker in the lldb debugger. It takes about 21 seconds for the debugger to stop at the first breakpoint at the SimpleStreamChecker::checkPreCall function when I run the following command:
>>>> 
>>>> lldb-6.0 -- clang-8 -cc1 -analyze -analyzer-checker=alpha.unix.SimpleStream \
>>>>  test/Analysis/simple-stream-checks.c
>>>> Are there ways to make it faster? I run many debugging sessions not only to figure out how the static analyzer works but also to debug my first checker. Any time saving method is appreciated.
>>>> 
>>>> -- 
>>>> Love,
>>>> Lou
>>>> 
>>>> _______________________________________________
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>>> 
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>> 
> 

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