[cfe-dev] Compile to ast and llvm bytecode using Clang API

[João Paulo Labegalini de Carvalho via cfe-dev]

Michael,

Exactly. I do not know if there is another way. I have a tool which runs,
for each source file, 3 AST Actions and generates a .bc using the code I
provided.

Something i did not try was to map a source file into a virtual one via
ClangTool::mapVirtualFile
<https://clang.llvm.org/doxygen/classclang_1_1tooling_1_1ClangTool.html>.
It seems that you can do it only once, then run your AST Actions and
finally generate code. But I am new to clang, so I might be wrong.

On Sun, Nov 11, 2018 at 7:48 PM Michael Collison <collison956 at gmail.com>
wrote:

> João,
>
> Thank you for your reply. I t appears from your response that I need to
> make "two passes" over the input file: one to generate my modified ast
> output file using FrontEndAction and a second pass using the code template
> your provided to generate the .bc file.
> On 11/11/2018 2:33 PM, João Paulo Labegalini de Carvalho wrote:
>
> Michael,
>
> The easiest way to use Clang API to perform "standard" compiler tasks is
> through the Driver class
> <https://clang.llvm.org/doxygen/classclang_1_1driver_1_1Driver.html>.
> Basically what you need to do is setup a command line invocation, using
> the flags from a compilation database or adding your own, build a
> Compilation object and execute it through the driver.
>
> For instance:
>
> std::string CommandLine = "clang++ -Wall -O3 -emit-llvm -o test.bc
> test.cpp";
> clang::DiagnosticOptions* DiagOptions = new DiagnosticOptions();
> clang::DiagnosticConsumer *DiagClient = new
> TextDiagnosticPrinter(llvm::errs(), DiagOptions);
> llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs> DiagID(new
> clang::DiagnosticIDs());
> clang::DiagnosticsEngine Diags(DiagID, DiagOptions, DiagClient);
> clang::driver::Driver TheDriver("clang++",
> llvm::sys::getDefaultTargetTriple(), Diags);
> const std::unique_ptr<driver::Compilation>
> compilation(TheDriver.BuildCompilation(CommandLine));
> if (!compilation) { llvm::errs() << "failed to build compilation
> object!\n"; }
> llvm::SmallVector<std::pair<int, const driver::Command*>,10>
> failingCommands;
> int res = TheDriver.ExecuteCompilation(*compilation, failingCommands);
> if (res < 0) {
>   ProcessingFailed = true;
>   for (const std::pair<int, const driver::Command*>& p : failingCommands) {
>     if (p.first) {
>       TheDriver.generateCompilationDiagnostics(*compilation, *p.second);
>     }
>   }
> }
>
>
> On Sun, Nov 11, 2018 at 6:53 PM Michael Collison via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> I have a requirement to parse a .cpp file to a .ast file and a .bc file.
>> I have the parsing, with filtering of the AST working using the the
>> tooling tempalte on this page:
>> https://clang.llvm.org/docs/RAVFrontendAction.html. I also need to
>> generate LLVM code to write out to a .bc file. I tried using :
>>
>> tool.run (newFrontEndActionFactory<EmitBCAction>().get())
>>
>> where tool is an instance of ClangTool but received an error saying "not
>> enough position command line arguments specified". Any ideas? Are there
>> any examples I can look at?
>>
>> Regards,
>>
>> Michael Collison
>>
>>
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
>
>
> --
> João Paulo L. de Carvalho
> Computer Science |  IC-UNICAMP | Campinas , SP - Brazil
> jaopaulolc at gmail.com
> joao.carvalho at ic.unicamp.br
> j160924 at dac.unicamp.br
>
>

-- 
João Paulo L. de Carvalho
Computer Science |  IC-UNICAMP | Campinas , SP - Brazil
jaopaulolc at gmail.com
joao.carvalho at ic.unicamp.br
j160924 at dac.unicamp.br
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