[cfe-dev] Plugin: Rewriter does not work?

[John Brawn via cfe-dev]

From a quick look at your code MyInstrumentation::getActionType is
returning AddAfterMainAction which means it's getting run after code
generation. To run it before code generation change that to
AddBeforeMainAction, which should hopefully make it do what you want.

John

> -----Original Message-----
> From: cfe-dev [mailto:cfe-dev-bounces at lists.llvm.org] On Behalf Of
> Marcel Schaible via cfe-dev
> Sent: 19 July 2017 20:26
> To: cfe-dev at lists.llvm.org
> Subject: Re: [cfe-dev] Plugin: Rewriter does not work?
> 
> Hi,
> 
> I need some advice. I want to create a plugin for clang which for e.g.
> alters the argument list of specific functions and insert valid c
> statements at certain points in the translation unit.
> 
> The Rewriter class is changing the source code as expected and I can
> write it to a temporary file and start the clang  compiler without my
> plugin again.
> 
> Is there a better solution like calling clang with my plugin and apply
> my changes on the fly?
> 
>  From my current understanding it is not possible to alter the AST in a
> plugin. Is this correct?
> 
> Thanks
> 
> Marcel
> 
> 
> Am 19.07.2017 um 14:28 schrieb Marcel Schaible via cfe-dev:
> > Hi,
> >
> > in my clang plugin I want to rewrite certain parts of the translation
> > unit. In the MyVisitor I'll setup a rewriter and try to replace for
> > e.g. the name of a function decl:
> >
> > TheRewriter.ReplaceText(funcDecl->getLocation(), funcName.length(),
> > "myreturn");
> >
> > This code is excecuted but the change is not visible in the generated
> > assembler file.
> >
> > Any idea what I am doing wrong?
> >
> > Thanks
> >
> > Marcel
> >
> > <---snippet--->
> >
> > Rewriter    TheRewriter;
> >
> > namespace {
> >
> >     class MyVisitor : public RecursiveASTVisitor<MyVisitor> {
> >     private:
> >         ASTContext *astContext;
> >
> >     public:
> >         explicit MyVisitor(CompilerInstance *CI) :
> > m_diag(CI->getDiagnostics()),
> >             astContext(&(CI->getASTContext()))
> >         {
> > TheRewriter.setSourceMgr(astContext->getSourceManager(),
> > astContext->getLangOpts());
> >         }
> >
> >         bool VisitFunctionDecl(const FunctionDecl *funcDecl) {
> >             string funcName =
> > funcDecl->getNameInfo().getName().getAsString();
> >             if (funcName == "return_fourtytwo") {
> > TheRewriter.ReplaceText(funcDecl->getLocation(), funcName.length(),
> > "myreturn");
> >                 errs() << "Rewrote function def: " << funcName <<
> "\n";
> >             }
> >
> >     private:
> >         DiagnosticsEngine &m_diag;
> >     };
> >
> >     class FuncDeclConsumer : public ASTConsumer {
> >     public:
> >         explicit FuncDeclConsumer(CompilerInstance *CI)
> >             : m_visitor(MyVisitor(CI)) {}
> >
> >         // Called by the parser for each top-level declaration group.
> >         // Returns true to continue parsing, or false to abort
> parsing.
> >         virtual bool HandleTopLevelDecl(DeclGroupRef dg) override {
> >             for (Decl *decl : dg) {
> >                 m_visitor.TraverseDecl(decl);
> >             }
> >             return true;
> >         }
> >
> >     private:
> >         MyVisitor m_visitor;
> >     };
> >
> >     class MyInstrumentation : public PluginASTAction {
> >     protected:
> >         std::unique_ptr<ASTConsumer>
> > CreateASTConsumer(CompilerInstance &ci,
> >             llvm::StringRef) override {
> >             return llvm::make_unique<FuncDeclConsumer>(&ci);
> >         }
> >
> >         PluginASTAction::ActionType getActionType() override {
> >             return AddAfterMainAction;
> >         }
> >     };
> > } // end namespace
> >
> > static FrontendPluginRegistry::Add<MyInstrumentation>
> > X("check-parameter-names", "check for parameter names mismatch");
> >
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> 
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev