llvm: dyld: Symbol not found: __ZN4llvm11RuntimeDyld13MemoryManager6anchorEv - llvm

Question

I am playing with LLVM and I hit an issue when trying to use JIT. I was able to build a compiler, it can be compiled, linked and it runs correctly (it compiles my toy programs). However, when I am trying to use build a JIT, it fails.
dyld: Symbol not found: __ZN4llvm11RuntimeDyld13MemoryManager6anchorEv
Referenced from: /Users/gruszczy/Projects/shwifty/./bazel-bin/_solib_darwin//liblibjit.so
Expected in: flat namespace
in /Users/gruszczy/Projects/shwifty/./bazel-bin/_solib_darwin//liblibjit.so
Abort trap: 6
I use Bazel to build everything, these are my build rules:
new_local_repository(
name = "llvm",
path = "/opt/local/libexec/llvm-4.0",
build_file= "llvm.BUILD")
cc_library(
name = "main",
srcs = glob(["lib/*.a"]),
hdrs = glob(["include/**/*.*"]),
visibility = ["//visibility:public"],
copts = ["-Iexternal/llvm/include"],
)
I use JIT in tests (I generate IR in the test then jit it, then run the method to see if it worked).
cc_library(
name = "jit",
srcs = ["jit.cc"],
hdrs = ["jit.h"],
deps = [
":ast",
":common",
"#llvm//:main"
],
copts = GENERAL_COPTS)
cc_test(
name = "codegen_test",
srcs = ["codegen_test.cc"],
deps = [
":ast",
":jit",
":lexer",
":parser",
":codegen",
"#gtest//:main",
"#llvm//:main"
],
copts = TEST_COPTS,
data = [":examples"],
size = "small"
)
Any suggestions what I might be missing?

Answer 1

The source of confusion is that Bazel by default links binaries statically, but tests dynamically. This makes the test-code-refactor loop faster, because changes to the test code only trigger the rebuild of the test, not the whole application. It can be disabled by setting linkstatic = 1 on codegen_test target.
As to why the symbols are not present in codegen_test when built as a shared library, that's much harder question and would need more project-specific information. But a possible solution might be to mark targets producing VMRuntimeDyld.a and VMMCJit.a as alwayslink = 1.
For the completeness, here's the link to an issue you reported on bazel.