Don't perform extra inference during incremental image creation (#48054)

As noted in #48047, we're currently attempting to infer extra
methods during incremental image saving, which causes us to miss
edges in the image. In particular, in the case of #48047, Cthulhu
had the `compile=min` option set, which caused the code instance
for `do_typeinf!` to not be infered. However, later it was
nevertheless queued for precompilation, causing inference to
occur at an inopportune time.

This PR simply prevents code instances that don't explicitly have
the `->precompile` flag set (e.g. the guard instance created for
the interpreter) from being enqueued for precompilation. It is
not clear that this is necessarily the correct behavior - we may
in fact want to infer these method instances, just before we set
up the serializer state, but for now this fixes #48047 for me.

I also included an appropriate test and a warning message if
we attempt to enter inference when this is not legal, so any
revisit of what should be happening here can hopefully make
use of those.

base/Base.jl

@@ -447,6 +447,10 @@ for m in methods(include)
     delete_method(m)
 end
 
+# This method is here only to be overwritten during the test suite to test
+# various sysimg related invalidation scenarios.
+a_method_to_overwrite_in_test() = inferencebarrier(1)
+
 # These functions are duplicated in client.jl/include(::String) for
 # nicer stacktraces. Modifications here have to be backported there
 include(mod::Module, _path::AbstractString) = _include(identity, mod, _path)

src/gf.c

@@ -280,6 +280,13 @@ jl_code_info_t *jl_type_infer(jl_method_instance_t *mi, size_t world, int force)
     if (jl_typeinf_func == NULL)
         return NULL;
     jl_task_t *ct = jl_current_task;
+    if (ct->reentrant_inference == (uint16_t)-1) {
+        // TODO: We should avoid attempting to re-inter inference here at all
+        // and turn on this warning, but that requires further refactoring
+        // of the precompile code, so for now just catch that case here.
+        //jl_printf(JL_STDERR, "ERROR: Attempted to enter inference while writing out image.");
+        return NULL;
+    }
     if (ct->reentrant_inference > 2)
         return NULL;
 

src/staticdata.c

@@ -2614,7 +2614,12 @@ JL_DLLEXPORT void jl_create_system_image(void **_native_data, jl_array_t *workli
         } else {
             checksumpos_ff = checksumpos;
         }
-        jl_gc_enable_finalizers(ct, 0); // make sure we don't run any Julia code concurrently after this point
+        {
+            // make sure we don't run any Julia code concurrently after this point
+            jl_gc_enable_finalizers(ct, 0);
+            assert(ct->reentrant_inference == 0);
+            ct->reentrant_inference = (uint16_t)-1;
+        }
         jl_prepare_serialization_data(mod_array, newly_inferred, jl_worklist_key(worklist), &extext_methods, &new_specializations, &method_roots_list, &ext_targets, &edges);
 
         // Generate _native_data`
@@ -2638,7 +2643,9 @@ JL_DLLEXPORT void jl_create_system_image(void **_native_data, jl_array_t *workli
     jl_save_system_image_to_stream(ff, worklist, extext_methods, new_specializations, method_roots_list, ext_targets, edges);
     native_functions = NULL;
     if (worklist) {
-        jl_gc_enable_finalizers(ct, 1); // make sure we don't run any Julia code concurrently before this point
+        // Re-enable running julia code for postoutput hooks, atexit, etc.
+        jl_gc_enable_finalizers(ct, 1);
+        ct->reentrant_inference = 0;
         jl_precompile_toplevel_module = NULL;
     }
 

test/precompile.jl

@@ -1691,6 +1691,23 @@ precompile_test_harness("DynamicExpressions") do load_path
     end
 end
 
+precompile_test_harness("BadInvalidations") do load_path
+    write(joinpath(load_path, "BadInvalidations.jl"),
+    """
+    module BadInvalidations
+        Base.Experimental.@compiler_options compile=min optimize=1
+        getval() = Base.a_method_to_overwrite_in_test()
+        getval()
+    end # module BadInvalidations
+    """)
+    Base.compilecache(Base.PkgId("BadInvalidations"))
+    (@eval Base a_method_to_overwrite_in_test() = inferencebarrier(2))
+    (@eval (using BadInvalidations))
+    Base.invokelatest() do
+        @test BadInvalidations.getval() === 2
+    end
+end
+
 empty!(Base.DEPOT_PATH)
 append!(Base.DEPOT_PATH, original_depot_path)
 empty!(Base.LOAD_PATH)