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<p class=MsoNormal>Dear Clang aficionados,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’d like to adapt Clang to accept a C extension,
perform a bit of analysis and then output LLVM IR. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>First, I learnt how to use Sema/ParseAST and
CodeGen/ModuleBuilder in the 2.6 release. However, since ParseAST in not re-enterable
I can’t do analysis and code generation at the same time. So I’d
really appreciate if you could point me to the right way of doing this!<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Second, I’m looking to the development branch. I
see some great looking API changes, such as introducing CompilerInstance and
CompilerInvocation, and a bunch of FrontendActions. I was hoping to use
FrontendActions for implementing my analysis and code gen, but no luck so far.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The minimal program <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>/// \file CompilerInstance.c<o:p></o:p></p>
<p class=MsoNormal>#include <clang/Frontend/FrontendActions.h><o:p></o:p></p>
<p class=MsoNormal>int main()<o:p></o:p></p>
<p class=MsoNormal>{<o:p></o:p></p>
<p class=MsoNormal> clang::EmitLLVMOnlyAction emitLLVM;<o:p></o:p></p>
<p class=MsoNormal>}<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>results in:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>lib/VMCore/Pass.cpp:228: void
<unnamed>::PassRegistrar::RegisterPass(const llvm::PassInfo&):
Assertion `Inserted && "Pass registered multiple times!"'
failed.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>In addition, by trial and error I figured out that I needed
to link against many Clang and LLVM libraries, e.g. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>g++ ./CompilerInstance.o -lclangFrontend
-lclangSema -lclangDriver -lclangAnalysis -lclangChecker -lclangRewrite
-lclangAST -lclangCodeGen -lclangLex -lclangBasic -lclangParse -lLLVMScalarOpts
-lLLVMInstCombine -lLLVMSelectionDAG -lLLVMipo -lLLVMipa -lLTO
-lLLVMTransformUtils -lLLVMBitWriter -lLLVMAnalysis -lLLVMCodeGen -lLLVMCore
-lLLVMMC -lLLVMSupport -lLLVMSystem -lLLVMTarget -lm -ldl –lpthread<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I find it weird that in order to use a FrontendAction that
only emits LLVM code I also need to link against so many optimisation libraries.
Can I conclude from this experience that FrontendActions are not supposed to be
used like this? (The same happens when I first initialise a CompilerInstance
properly and then declare an EmitLLVMOnlyAction object.) Again, what
would be the right way to do this?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’d really appreciate your help and hope to become
part of the developer community soon!<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Many thanks,<o:p></o:p></p>
<p class=MsoNormal>Anton.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>P.S. I’m almost as desperate as Devin Townsend’s
Ziltoid:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>[Narrator:] Having been rejected by the Planet smasher,
Ziltoid seeks the council of the Omnidimensional Creator.<br>
[Ziltoid:] Assuage my confusion about creation and the universe!<o:p></o:p></p>
<p class=MsoNormal>[Creator:] Yo! Ziltoid, what’s up dude?<o:p></o:p></p>
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