path: root/content/2022-07-07-llvm-orc-jit/main.cc

#include "ccompiler.h"
#include "jit.h"

int main() {
  const char code[] =
      "extern void libc_puts(const char*);"
      "struct S { int a; int b; };"
      "static void init_a(struct S* s) { s->a = 1111; }"
      "static void init_b(struct S* s) { s->b = 2222; }"
      "void init(struct S* s) {"
      "init_a(s); init_b(s);"
      "libc_puts(\"libc_puts()\"); }";

  auto R = cc::CCompiler().compile(code);
  // Abort if compilation failed.
  auto [C, M] = cantFail(std::move(R));
  // M->print(llvm::errs(), nullptr);

  // -- JIT compiler the IR module.

  llvm::InitializeNativeTarget();
  llvm::InitializeNativeTargetAsmPrinter();

  auto JIT = jit::Jit::Create();
  auto TSM = llvm::orc::ThreadSafeModule(std::move(M), std::move(C));

  auto RT = JIT->addModule(std::move(TSM));
  if (auto E = RT.takeError()) {
    llvm::errs() << llvm::toString(std::move(E)) << '\n';
    return 1;
  }

  if (auto ADDR = JIT->lookup("init")) {
    std::printf("JIT ADDR 0x%lx\n", (*ADDR).getAddress().getValue());

    struct S {
      int a, b;
    } state = {0, 0};
    auto JIT_FN = (*ADDR).getAddress().toPtr<void(struct S*)>();

    std::printf("S { a=%d b=%d }\n", state.a, state.b);
    JIT_FN(&state);
    std::printf("S { a=%d b=%d }\n", state.a, state.b);
  }

  // Remove jitted code tracked by this RT.
  cantFail((*RT)->remove());

  if (auto E = JIT->lookup("init").takeError()) {
    // In ERROR state, as expected, consume the error.
    llvm::consumeError(std::move(E));
  } else {
    // In SUCCESS state, not expected as code was dropped.
    llvm::errs() << "Expected error, we removed code tracked by RT and "
                    "hence 'init' should be "
                    "removed from the JIT!\n";
  }

  return 0;
}