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<p class="MsoNormal"><span style="color:#1F497D">What’s happening here is some slightly non-obvious behaviour in how ASTConsumers are used.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">In brief:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">* Adding a PluginASTAction means we get a MultiplexConsumer whose list of consumers<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> is FuncnameChangeAction then the main action<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">* This means that for each of the HandleXXX functions it calls the HandleXXX function on the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> FuncnameChangeAction then the main action<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">* clang::parseAST is where it ultimately ends up using the MultiplexConsumer and there it<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> calls HandleTopLevelDecl on each DeclGroup
<i>then</i> calls HandleTranslationUnit<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">* You’ve done your transformation in HandleTranslationUnit, but CodeGenAction generates code<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> in HandleTopLevelDecl, so though your HandleTranslationUnit is called before the CodeGenAction’s<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> HandleTranslationUnit it doesn’t matter because the code has already been generated.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">* Doing the transformation in HandleTopLevelDecl works<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">(I myself didn’t realise that this would happen, I only figured it out by running clang in a debugger,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">setting breakpoints at various places and trying to figure out what was going on.)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">John</span><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Ori Zaig [mailto:oriz@mellanox.com]
<br>
<b>Sent:</b> 28 November 2016 12:58<br>
<b>To:</b> John Brawn<br>
<b>Cc:</b> Eran Jakoby; nd; cfe-dev@lists.llvm.org<br>
<b>Subject:</b> RE: AST modifications that apply to the binary<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Unfortunately it doesn’t work - maybe I’m missing something…<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">I added the </span>
<span style="color:#1F497D">getActionType method:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">class FuncnameChangeAction: public PluginASTAction {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI, llvm::StringRef InFile) override {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return llvm::make_unique< FuncnameChangeConsumer >(CI, &CI.getSourceManager());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> bool ParseArgs(const CompilerInstance &CI, const std::vector<std::string> &args) override {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return true;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt"><b><span lang="EN-US">virtual ActionType getActionType() override { return AddBeforeMainAction; }<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">And used the below command line:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">clang++ -Xclang -load -Xclang ModifyFunc.so -Xclang -add-plugin -Xclang modify-func -c some_code.cpp -o some_code.o<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">And yet, changes were not reflected in the binary (some_code.o) or even in IR<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D">Any other ideas please?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> John Brawn [<a href="mailto:John.Brawn@arm.com">mailto:John.Brawn@arm.com</a>]
<br>
<b>Sent:</b> Wednesday, November 23, 2016 7:14 PM<br>
<b>To:</b> Ori Zaig <<a href="mailto:oriz@mellanox.com">oriz@mellanox.com</a>><br>
<b>Cc:</b> Eran Jakoby <<a href="mailto:eranj@mellanox.com">eranj@mellanox.com</a>>; nd <<a href="mailto:nd@arm.com">nd@arm.com</a>>;
<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a><br>
<b>Subject:</b> RE: AST modifications that apply to the binary<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">By default a PluginASTAction will replace the main AST action (if you use -plugin pluginname on the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">cc1 command line) or go after the main AST action (if you use -add-plugin pluginname on the cc1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">command line), where the “main AST action” is “generate an object file” if using -c, “generate<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">assembly” is using -S, etc.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">If you want the PluginASTAction to go before the main AST action, i.e. you want it to change the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">AST in a way that will affect the compiled output, then define a getActionType method in the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">PluginASTAction which returns AddBeforeMainAction.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">John<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> cfe-dev [</span><span lang="EN-US"><a href="mailto:cfe-dev-bounces@lists.llvm.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">mailto:cfe-dev-bounces@lists.llvm.org</span></a></span><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">]
<b>On Behalf Of </b>Ori Zaig via cfe-dev<br>
<b>Sent:</b> 20 November 2016 16:49<br>
<b>To:</b> </span><span lang="EN-US"><a href="mailto:cfe-dev@lists.llvm.org"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">cfe-dev@lists.llvm.org</span></a></span><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""><br>
<b>Cc:</b> Eran Jakoby<br>
<b>Subject:</b> [cfe-dev] AST modifications that apply to the binary<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">Hi all<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Is there any possible making AST modification that finally will be reflected in the binary?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I tried doing that via plugin, for instance changing a method name (let’s say turn foo() to my_foo() ) such:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">class FuncnameChangeVisitor : public RecursiveASTVisitor< FuncnameChangeVisitor > {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">private:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> ASTContext *m_context;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">public:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> /* some code */<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> bool VisitFunctionDecl(FunctionDecl *f) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> DeclarationNameInfo newNameInfo(f->getNameInfo());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> DeclarationName origName(f->getDeclName());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> std::string newName("my_");<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> newName += origName.getAsString();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> IdentifierInfo& newNameIdInfo(m_context->Idents.get(StringRef(newName.c_str())));<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> f->setDeclName(DeclarationName(&newNameIdInfo));<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return true;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">class FuncnameChangeConsumer: public ASTConsumer {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">private:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> FuncnameChangeVisitor m_visitor;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">public:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> /* some code*/<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> virtual void HandleTranslationUnit(ASTContext &Cntx) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> m_visitor.TraverseDecl(Cntx.getTranslationUnitDecl());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">class FuncnameChangeAction: public PluginASTAction {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI, llvm::StringRef InFile) override {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return llvm::make_unique< FuncnameChangeConsumer >(CI, &CI.getSourceManager());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> bool ParseArgs(const CompilerInstance &CI, const std::vector<std::string> &args) override {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return true;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">static FrontendPluginRegistry::Add< FuncnameChangeAction > reg("modify-func", "add my_ prefix to funtions");<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">But in vain… I understood that the IR and hence the binary are generated regardless the plugins<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">And if there isn’t a way to do so, is there another way via Clang to make code-modifications that affect the binary, which are not source-to-source compilation?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Tnx<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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