llvm: small ORCv2 jit example

1 files changed, 55 insertions, 0 deletions

diff --git a/content/2022-07-07-llvm-orc-jit/main.cc b/content/2022-07-07-llvm-orc-jit/main.cc
new file mode 100644
index 0000000..1631990
--- /dev/null
+++ b/content/2022-07-07-llvm-orc-jit/main.cc
@@ -0,0 +1,55 @@
+#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());
+
+    struct S {
+      int a, b;
+    } state = {0, 0};
+    auto JIT_FN = (void (*)(struct S *))(*ADDR).getAddress();
+
+    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.
+  (void)(*RT)->remove();
+
+  if (auto E = JIT->lookup("init").takeError()) {
+    llvm::errs() << "Expected error, we dropped removed code tracked by RT and "
+                    "hence 'init' should be "
+                    "removed from the JIT!\n";
+  }
+
+  return 0;
+}