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

[João Paulo Labegalini de Carvalho via cfe-dev]

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
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