Register the symbol context's module's AST files first.

This makes it more likely that compatible AST blobs are found first,
since then the local AST blobs overwrite any ones with the same import
path from another dylib. The AST blobs are registered in a DFS
following the dynamic library dependencies in the binary.

Author: adrian-prantl

lldb/packages/Python/lldbsuite/test/make/Makefile.rules

@@ -818,18 +818,17 @@ DYLIB_SWIFT_FLAGS=  \
         -Xlinker -install_name -Xlinker "$(DYLIB_INSTALL_NAME)" \
         $(LD_EXTRAS)
 ifeq "$(DYLIB_HIDE_SWIFTMODULE)" ""
-DYLIB_SWIFT_FLAGS+= -Xlinker -add_ast_path -Xlinker $(DYLIB_NAME).swiftmodule
+DYLIB_SWIFT_FLAGS+= -Xlinker -add_ast_path -Xlinker $(MODULENAME).swiftmodule
 endif
 else
 DYLIB_SWIFT_FLAGS=$(LD_EXTRAS)
+ifeq "$(DYLIB_HIDE_SWIFTMODULE)" ""
+DYLIB_OBJECTS += $(BUILDDIR)/$(MODULENAME).o
+endif
 endif
+
 $(DYLIB_FILENAME) : $(DYLIB_OBJECTS) $(MODULE_INTERFACE)
 	@echo "### Linking dynamic library $(DYLIB_NAME)"
-ifneq "$(DYLIB_HIDE_SWIFTMODULE)" ""
-	$(SWIFTC) $(patsubst -g,,$(SWIFTFLAGS)) \
-            -emit-library $(DYLIB_SWIFT_FLAGS) -o $@ \
-            $(patsubst %.swiftmodule.o,,$(DYLIB_OBJECTS))
-else
 ifneq "$(FRAMEWORK)" ""
 	mkdir -p $(FRAMEWORK).framework/Versions/A/Headers
 	mkdir -p $(FRAMEWORK).framework/Versions/A/Modules
@@ -846,7 +845,6 @@ endif
 endif
 	$(SWIFTC) $(patsubst -g,,$(SWIFTFLAGS)) \
             -emit-library $(DYLIB_SWIFT_FLAGS) -o $@ $(DYLIB_OBJECTS)
-endif
 ifneq "$(CODESIGN)" ""
 	$(CODESIGN) -s - "$(DYLIB_FILENAME)"
 endif

lldb/source/Plugins/TypeSystem/Swift/SwiftASTContext.cpp

@@ -2981,10 +2981,56 @@ lldb::TypeSystemSP SwiftASTContext::CreateInstance(
                                plugin_search_options.begin(),
                                plugin_search_options.end());
 
+  // Register the symbol context's module first. This makes it more
+  // likely that compatible AST blobs are found first, since then the
+  // local AST blobs overwrite any ones with the same import path from
+  // another dylib.
+  llvm::DenseSet<Module *> visited_modules;
+  llvm::StringMap<ModuleSP> all_modules;
   for (size_t mi = 0; mi != num_images; ++mi) {
-    std::vector<std::string> module_names;
-    auto module_sp = target.GetImages().GetModuleAtIndex(mi);
-    swift_ast_sp->RegisterSectionModules(*module_sp, module_names);
+    auto image_sp = target.GetImages().GetModuleAtIndex(mi);
+    std::string path = image_sp->GetSpecificationDescription();
+    all_modules.insert({path, image_sp});
+    all_modules.insert({llvm::sys::path::filename(path), image_sp});
+  }
+  std::vector<std::string> module_names;
+  std::function<void(ModuleSP, unsigned)> scan_module =
+      [&](ModuleSP cur_module_sp, unsigned indent) {
+        if (!cur_module_sp ||
+            !visited_modules.insert(cur_module_sp.get()).second)
+          return;
+        swift_ast_sp->RegisterSectionModules(*cur_module_sp, module_names);
+        if (GetLog(LLDBLog::Types)) {
+          std::string spacer(indent, '-');
+          LOG_PRINTF(GetLog(LLDBLog::Types), "+%s Dependency scan: %s",
+                     spacer.c_str(),
+                     cur_module_sp->GetSpecificationDescription().c_str());
+        }
+        if (auto object = cur_module_sp->GetObjectFile()) {
+          FileSpecList file_list;
+          object->GetDependentModules(file_list);
+          for (auto &fs : file_list) {
+            if (ModuleSP dependency = all_modules.lookup(fs.GetPath())) {
+              scan_module(dependency, indent + 1);
+            } else if (ModuleSP dependency =
+                           all_modules.lookup(fs.GetFilename())) {
+              scan_module(dependency, indent + 1);
+            } else {
+              if (GetLog(LLDBLog::Types)) {
+                std::string spacer(indent, '-');
+                LOG_PRINTF(GetLog(LLDBLog::Types),
+                           "+%s Could not find %s in images", spacer.c_str(),
+                           fs.GetPath().c_str());
+              }
+            }
+          }
+        }
+      };
+  scan_module(module_sp, 0);
+  for (size_t mi = 0; mi != num_images; ++mi) {
+    auto image_sp = target.GetImages().GetModuleAtIndex(mi);
+    if (!visited_modules.count(image_sp.get()))
+      swift_ast_sp->RegisterSectionModules(*image_sp, module_names);
   }
 
   LOG_PRINTF(GetLog(LLDBLog::Types), "((Target*)%p) = %p",
@@ -4372,6 +4418,7 @@ void SwiftASTContext::RegisterSectionModules(
 
   // Grab all the AST blobs from the symbol vendor.
   auto ast_file_datas = module.GetASTData(eLanguageTypeSwift);
+    if (ast_file_datas.size())
   LOG_PRINTF(GetLog(LLDBLog::Types),
              "(\"%s\") retrieved %zu AST Data blobs from the symbol vendor "
              "(filter=\"%s\").",

lldb/test/API/lang/swift/deployment_target/TestSwiftDeploymentTarget.py

@@ -65,4 +65,4 @@ def test_swift_deployment_target_from_macho(self):
         self.expect("expression f", substrs=["i = 23"])
         self.filecheck('platform shell cat ""%s"' % log, __file__)
 #       CHECK: SwiftASTContextForExpressions::SetTriple({{.*}}apple-macosx11.0.0
-#       CHECK:  SwiftASTContextForExpressions::RegisterSectionModules("a.out") retrieved 0 AST Data blobs
+#       CHECK-NOT: SwiftASTContextForExpressions::RegisterSectionModules("a.out"){{.*}} AST Data blobs

lldb/test/API/lang/swift/expression/import_search_paths/TestSwiftImportSearchPaths.py

@@ -30,22 +30,19 @@ def do_test(self, flag):
             self, 'break here', lldb.SBFileSpec('main.swift'),
             extra_images=['Direct', self.getBuildArtifact('hidden/libIndirect')])
 
-        log = self.getBuildArtifact("types.log")
-        self.expect('settings show '
-                    + 'target.experimental')
-        self.expect("log enable lldb types -f " + log)
+        types_log = self.getBuildArtifact("types.log")
+        self.expect("log enable lldb types -f " + types_log)
         self.expect("expr -- x.inner.hidden", substrs=['=', '42'])
-
-        import io, re
-        logfile = io.open(log, "r", encoding='utf-8')
-        sanity = 0
-        found = 0
-        for line in logfile:
-            if re.match(r'.*SwiftASTContextForModule\("a\.out"\)::LogConfiguration\(\).*hidden$',
-                        line.strip('\n')):
-                sanity += 1
-            elif re.match(r'.*SwiftASTContextForExpressions::LogConfiguration\(\).*hidden$',
-                          line.strip('\n')):
-                found += 1
-        self.assertEqual(sanity, 1)
-        self.assertEqual(found, 1 if flag == 'true' else 0)
+        if flag == 'true':
+            prefix = 'POSITIVE'
+        else:
+            prefix = 'NEGATIVE'
+        self.filecheck('platform shell cat "%s"' % types_log, __file__,
+                       '--check-prefix=CHECK_MOD_'+prefix)
+        self.filecheck('platform shell cat "%s"' % types_log, __file__,
+                       '--check-prefix=CHECK_EXP_'+prefix)
+# CHECK_MOD_POSITIVE: SwiftASTContextForModule("a.out")::LogConfiguration(){{.*hidden$}}
+# CHECK_MOD_NEGATIVE: SwiftASTContextForModule("a.out")::LogConfiguration(){{.*hidden$}}
+# CHECK_EXP_POSITIVE: SwiftASTContextForExpressions::LogConfiguration(){{.*hidden$}}
+# CHECK_EXP_NEGATIVE-NOT: SwiftASTContextForExpressions::LogConfiguration(){{.*hidden$}}
+# CHECK_EXP_NEGATIVE: SwiftASTContextForExpressions::LogConfiguration(){{.*}}Extra clang arguments