LLVM example

set -x # print commands
set -e # abort on error

WORKS=works.bc
WORKS2=works2.bc
CRASHES=crashes.bc
PROGRAM=program

clang++ $(llvm-config --cxxflags) -c -x c++ - -emit-llvm -o $WORKS <<EOF

  #include <iostream>

  class A {
    public:
       A(void) {
          std::cout << "AAA\n";
       }
  };

  extern "C" {
    void makeit() { A(); }
  }

EOF

clang++ -O2 $(llvm-config --cxxflags) -c -x c++ - -emit-llvm -o $WORKS2 <<EOF

  #include <iostream>

  class B {
    public:
       B(void);
  };

  B::B(void) {
          std::cout << "BBB\n";
  }

  extern "C" {
    void makeit() { B(); }
  }

EOF

clang++ $(llvm-config --cxxflags) -c -x c++ - -emit-llvm -o $CRASHES <<EOF

  #include <iostream>

  class C {
    public:
       C(void);
  };

  C::C(void) {
          std::cout << "CCC\n";
  }

  extern "C" {
    void makeit() { C(); }
  }

EOF


clang++ $(llvm-config --cxxflags) -x c++ - $(llvm-config --ldflags) $(llvm-config --libs jit native BitReader) -o $PROGRAM <<EOF

 #include <iostream>

 #include <llvm/LLVMContext.h>
 #include <llvm/Target/TargetSelect.h>
 #include <llvm/Bitcode/ReaderWriter.h>
 #include <llvm/ExecutionEngine/ExecutionEngine.h>
 #include <llvm/Support/MemoryBuffer.h>
 #include <llvm/ExecutionEngine/JIT.h>
 #include <llvm/ADT/OwningPtr.h>
 #include "llvm/Support/system_error.h"

 using namespace std;
 using namespace llvm;

 int main(int argc, char** argv)
 {
   if(argc<=1) {
     return 1;
   }

   const char* filename = argv[1];

   InitializeNativeTarget();
   llvm_start_multithreaded();

   LLVMContext context;
   OwningPtr<MemoryBuffer> buffer;

   if (error_code ec = MemoryBuffer::getFile(filename, buffer)) {
     return 1;
   } else {
     std::string ParseErrorMessage;
     Module* m = ParseBitcodeFile(buffer.get(), context, &ParseErrorMessage);
     if(m) {
       ExecutionEngine *ee = ExecutionEngine::create(m);
       Function* func = ee->FindFunctionNamed("makeit");
       if(func) {
     typedef void (*PFN)();
     cout << "starting to JIT makeit" << endl;
     PFN pfn = reinterpret_cast<PFN>(ee->getPointerToFunction(func));
     pfn();
       } else {
     return 1;
       }
       delete ee;
     } else {
       return 1;
     }
   }
   return 0;
 }

EOF

./$PROGRAM  $WORKS
./$PROGRAM  $WORKS2
./$PROGRAM  $CRASHES


cat << EOF
$ clang -v
clang version 3.0 (http://llvm.org/git/clang.git ec5bc81fd55bfcc26fc4bde6d5e33113d94c2209)
Target: i386-pc-linux-gnu
Thread model: posix
$ llvmc --version
Low Level Virtual Machine (http://llvm.org/):
  llvm version 3.0svn
  DEBUG build with assertions.
  Built Aug 23 2011 (12:10:27).
  Host: i386-pc-linux-gnu
  Host CPU: penryn
EOF