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

Lou Wynn via cfe-dev cfe-dev at lists.llvm.org
Wed Oct 3 11:44:19 PDT 2018


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.

(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
>>>
>>> _______________________________________________
>>> cfe-dev mailing list
>>> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>> _______________________________________________
>> cfe-dev mailing list
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