[cfe-dev] How clang works, whant to learn compiler internals

[Cesar Mello via cfe-dev]

Awesome, thank you too!

Best regards
Cesar

On Tue, Oct 18, 2016 at 6:12 AM, Serge Pavlov via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> You need to pass argument "-cc1" to the compiler in debug session. In your
> case parameters must be:
> -cc1 -std=c++1z -Xclang -ast-dump -fsyntax-only test_deb.cpp
>
> Without "-cc1" clang works as driver executing other tools to make job,
> with "-cc1" it works as compiler.
>
> Thanks,
> --Serge
>
> 2016-10-18 14:54 GMT+07:00 Ivan Kush via cfe-dev <cfe-dev at lists.llvm.org>:
>
>> I want to learn clang internals and how it works. But
>> llvm::sys::ExecuteAndWait executes in the debugger and that's all, finish,
>> console output with my AST (I passes to clang "-ast-dump"). It didn't jump
>> in the Lexer.cpp, Sema.cpp, etc. What should I do in the debugger, in order
>> to see how Lexer, Sema work?
>>
>> My steps in the debugger:
>>
>> 1) compiled debug version of llvm and clang
>>
>> 2) created a source file "test_deb.cpp" with  the following code
>>
>> enum class Enum : int
>> {
>>     kOne,
>>     kTwo
>> };
>>
>> int f(int x) {
>>   int result = (x / 42);
>>   return result;
>> }
>>
>> int main()
>> {
>>     return f(4);
>> }
>>
>> 3) launch clang-4.0 in in the debugger with the following parameters:
>> -std=c++1z -Xclang -ast-dump -fsyntax-only test_deb.cpp
>>
>> 4)  and begin to learn how all work:
>> the "int main" in driver.cpp
>>
>> in driver.cpp is called "ExecuteCompilation" of "Driver"
>>     TheDriver.ExecuteCompilation(*C, FailingCommands);
>>
>> where called "ExecuteJobs" of "Compilation" (the file Compilation.cpp):
>>     C.ExecuteJobs(C.getJobs(), FailingCommands);
>>
>> in the func ExecuteJobs called ExecuteCommand
>>     if (int Res = ExecuteCommand(Job, FailingCommand)) {
>>
>> that calls "Execute" of "Command" (the file Jobs.cpp):
>>
>> where called a func "ExecuteAnddWait" of  "llvm::sys"
>>
>>     return llvm::sys::ExecuteAndWait(Executable, Argv.data(), /*env*/
>> nullptr,
>>                                      Redirects, /*secondsToWait*/ 0,
>>                                      /*memoryLimit*/ 0, ErrMsg,
>>                                      ExecutionFailed);
>>
>> but the "Executable" is "...path/clang-4.0" - the file, that I launched
>> in the debugger o__O
>>
>> 5) so llvm::sys::ExecuteAndWait(Executable,...) is called and that's
>> all, finish, console output with my AST. It didn't jump in the Lexer.cpp,
>> Sema.cpp, etc.
>>
>> What should I do in the debugger, in order to see how Lexer, Sema work?
>>
>> --
>> Best wishes,
>> Ivan Kush
>>
>>
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>> cfe-dev at lists.llvm.org
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>>
>>
>
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