Don't emit module metadata for non-toplevel modules.

src/aotcompile.cpp

@@ -813,9 +813,10 @@ void *jl_emit_native_impl(jl_array_t *codeinfos, LLVMOrcThreadSafeModuleRef llvm
                 continue; // skip any duplicates that accidentally made there way in here (or make this an error?)
             if (jl_ir_inlining_cost((jl_value_t*)src) < UINT16_MAX)
                 params.safepoint_on_entry = false; // ensure we don't block ExpandAtomicModifyPass from inlining this code if applicable
-            orc::ThreadSafeModule result_m = jl_create_ts_module(name_from_method_instance(jl_get_ci_mi(codeinst)),
-                    params.tsctx, clone.getModuleUnlocked()->getDataLayout(),
-                    Triple(clone.getModuleUnlocked()->getTargetTriple()));
+            orc::ThreadSafeModule result_m = jl_create_ts_module(
+                name_from_method_instance(jl_get_ci_mi(codeinst)), params.tsctx,
+                clone.getModuleUnlocked()->getDataLayout(),
+                Triple(clone.getModuleUnlocked()->getTargetTriple()), false);
             jl_llvm_functions_t decls;
             if (!(params.params->force_emit_all) && jl_atomic_load_relaxed(&codeinst->invoke) == jl_fptr_const_return_addr)
                 decls.functionObject = "jl_fptr_const_return";

src/codegen.cpp

@@ -2682,17 +2682,12 @@ static jl_cgval_t convert_julia_type(jl_codectx_t &ctx, const jl_cgval_t &v, jl_
     return jl_cgval_t(v, typ, new_tindex);
 }
 
-std::unique_ptr<Module> jl_create_llvm_module(StringRef name, LLVMContext &context, const DataLayout &DL, const Triple &triple) JL_NOTSAFEPOINT
+std::unique_ptr<Module> jl_create_llvm_module(StringRef name, LLVMContext &context,
+                                              const DataLayout &DL, const Triple &triple,
+                                              bool toplevel) JL_NOTSAFEPOINT
 {
     ++ModulesCreated;
     auto m = std::make_unique<Module>(name, context);
-    // According to clang darwin above 10.10 supports dwarfv4
-    if (!m->getModuleFlag("Dwarf Version")) {
-        m->addModuleFlag(llvm::Module::Warning, "Dwarf Version", 4);
-    }
-    if (!m->getModuleFlag("Debug Info Version"))
-        m->addModuleFlag(llvm::Module::Warning, "Debug Info Version",
-            llvm::DEBUG_METADATA_VERSION);
     m->setDataLayout(DL);
     m->setTargetTriple(triple.str());
 
@@ -2703,9 +2698,19 @@ std::unique_ptr<Module> jl_create_llvm_module(StringRef name, LLVMContext &conte
         m->setOverrideStackAlignment(16);
     }
 
+    // when this is a toplevel module, add additional flags.
+    // otherwise, these are inherited from the parent module when linking.
+    if (toplevel) {
+        // According to clang darwin above 10.10 supports dwarfv4
+        m->addModuleFlag(llvm::Module::Warning, "Dwarf Version", 4);
+        m->addModuleFlag(llvm::Module::Warning, "Debug Info Version",
+                         llvm::DEBUG_METADATA_VERSION);
+
 #if defined(JL_DEBUG_BUILD)
-    m->setStackProtectorGuard("global");
+        m->setStackProtectorGuard("global");
 #endif
+    }
+
     return m;
 }
 

src/jitlayers.h

@@ -671,15 +671,22 @@ class JuliaOJIT {
     OptSelLayerT OptSelLayer;
 };
 extern JuliaOJIT *jl_ExecutionEngine;
-std::unique_ptr<Module> jl_create_llvm_module(StringRef name, LLVMContext &ctx, const DataLayout &DL, const Triple &triple) JL_NOTSAFEPOINT;
-inline orc::ThreadSafeModule jl_create_ts_module(StringRef name, orc::ThreadSafeContext ctx, const DataLayout &DL, const Triple &triple) JL_NOTSAFEPOINT {
+std::unique_ptr<Module> jl_create_llvm_module(StringRef name, LLVMContext &ctx,
+                                              const DataLayout &DL, const Triple &triple,
+                                              bool toplevel) JL_NOTSAFEPOINT;
+inline orc::ThreadSafeModule jl_create_ts_module(StringRef name, orc::ThreadSafeContext ctx,
+                                                 const DataLayout &DL, const Triple &triple,
+                                                 bool toplevel = true) JL_NOTSAFEPOINT
+{
     auto lock = ctx.getLock();
-    return orc::ThreadSafeModule(jl_create_llvm_module(name, *ctx.getContext(), DL, triple), ctx);
+    return orc::ThreadSafeModule(
+        jl_create_llvm_module(name, *ctx.getContext(), DL, triple, toplevel), ctx);
 }
 
 Module &jl_codegen_params_t::shared_module() JL_NOTSAFEPOINT {
     if (!_shared_module) {
-        _shared_module = jl_create_llvm_module("globals", getContext(), DL, TargetTriple);
+        _shared_module =
+            jl_create_llvm_module("globals", getContext(), DL, TargetTriple, true);
     }
     return *_shared_module;
 }