Support debugging Swift dylibs that were loaded after SwiftASTContext was initialized.

This patch extends the ModulesDidLoad callback to register .swiftast
sections in the new dylib and posons the context if necessary to force
a reinitialization.

rdar://81135636

Author: adrian-prantl

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

@@ -1949,7 +1949,7 @@ static lldb::ModuleSP GetUnitTestModule(lldb_private::ModuleList &modules) {
 /// Scan a newly added lldb::Module fdor Swift modules and report any errors in
 /// its module SwiftASTContext to Target.
 static void
-ProcessModule(ModuleSP &&module_sp, std::string m_description,
+ProcessModule(ModuleSP module_sp, std::string m_description,
               bool use_all_compiler_flags, Target &target,
               std::vector<std::string> &module_search_paths,
               std::vector<std::pair<std::string, bool>> &framework_search_paths,
@@ -5069,6 +5069,37 @@ void SwiftASTContext::PrintDiagnostics(DiagnosticManager &diagnostic_manager,
 
 void SwiftASTContext::ModulesDidLoad(ModuleList &module_list) {
   ClearModuleDependentCaches();
+
+  // Scan the new modules for Swift contents and try to import it if
+  // safe, otherwise poison this context.
+  TargetSP target_sp = GetTarget().lock();
+  if (!target_sp)
+    return;
+
+  bool use_all_compiler_flags = target_sp->GetUseAllCompilerFlags();
+  unsigned num_images = module_list.GetSize();
+  for (size_t mi = 0; mi != num_images; ++mi) {
+    std::vector<std::string> module_search_paths;
+    std::vector<std::pair<std::string, bool>> framework_search_paths;
+    std::vector<std::string> extra_clang_args;
+    lldb::ModuleSP module_sp = module_list.GetModuleAtIndex(mi);
+    ProcessModule(module_sp, m_description, use_all_compiler_flags, *target_sp,
+                  module_search_paths, framework_search_paths,
+                  extra_clang_args);
+    // If the use-all-compiler-flags setting is enabled, the expression
+    // context is supposed to merge all search paths form all dylibs.
+    if (use_all_compiler_flags && !extra_clang_args.empty()) {
+      // We cannot reconfigure ClangImporter after its creation.
+      // Instead poison the SwiftASTContext so it gets recreated.
+      m_fatal_errors.SetErrorStringWithFormat(
+          "New Swift image added: %s",
+          module_sp->GetFileSpec().GetPath().c_str());
+    }
+
+    // Scan the dylib for .swiftast sections.
+    std::vector<std::string> module_names;
+    RegisterSectionModules(*module_sp, module_names);
+  }
 }
 
 void SwiftASTContext::ClearModuleDependentCaches() {

lldb/test/API/lang/swift/late_dylib/Makefile

@@ -0,0 +1,21 @@
+# This Makefile recursively calls itself, hence the ?=.
+EXE ?= a.out
+C_SOURCES ?= loader.c
+all: dylib $(EXE)
+
+include Makefile.rules
+
+.PHONY: dylib
+dylib:
+	$(MAKE) MAKE_DSYM=$(MAKE_DSYM) CC=$(CC) SWIFTC=$(SWIFTC) \
+		ARCH=$(ARCH) DSYMUTIL=$(DSYMUTIL) \
+		VPATH=$(SRCDIR) -I $(SRCDIR) \
+		-f $(SRCDIR)/Makefile \
+		DYLIB_FILENAME=dylib.dylib \
+		DYLIB_SWIFT_SOURCES=dylib.swift \
+		DYLIB_NAME=dylib \
+		DYLIB_ONLY=YES \
+		C_SOURCES= \
+		LD_EXTRAS="-lSwiftCore -Xlinker -exported_symbol -Xlinker _f" \
+		dylib.dylib
+

lldb/test/API/lang/swift/late_dylib/TestSwiftLateDylib.py

@@ -0,0 +1,21 @@
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestSwiftLateDylib(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipUnlessDarwin
+    @swiftTest
+    @skipIfDarwinEmbedded 
+    def test(self):
+        """Test that a late loaded Swift dylib is debuggable"""
+        self.build()
+        target, process, _, _ = lldbutil.run_to_name_breakpoint(self, "main")
+        # Initialize SwiftASTContext before loading the dylib.
+        self.expect("expr -l Swift -- 0")
+        bkpt = target.BreakpointCreateByLocation(lldb.SBFileSpec('dylib.swift'), 7)
+        lldbutil.continue_to_breakpoint(process, bkpt)
+        self.expect("v x", substrs=['Hello from the Dylib'])
+        self.expect("expr x", substrs=['Hello from the Dylib'])

lldb/test/API/lang/swift/late_dylib/dylib.swift

@@ -0,0 +1,8 @@
+struct FromDylib {
+    let msg = "Hello from the Dylib!"
+}
+
+@_silgen_name("f") public func f() {
+  let x = FromDylib()
+  print(x) // line 7
+}

lldb/test/API/lang/swift/late_dylib/loader.c

@@ -0,0 +1,12 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <string.h>
+#include <libgen.h>
+
+int main(int argc, const char **argv) {
+  char *dylib_name = strcat(dirname(argv[0]),"/dylib.dylib");
+  void *dylib = dlopen(dylib_name, RTLD_NOW);
+  void (*f)() = dlsym(dylib, "f");
+  f();
+  return 0;
+}

lldb/test/API/lang/swift/late_dylib_clangdeps/ClangMod.h

@@ -0,0 +1,3 @@
+struct FromClang {
+  int x;
+};

lldb/test/API/lang/swift/late_dylib_clangdeps/Makefile

@@ -0,0 +1,22 @@
+# This Makefile recursively calls itself, hence the ?=.
+EXE ?= a.out
+C_SOURCES ?= loader.c
+all: dylib $(EXE)
+
+include Makefile.rules
+
+.PHONY: dylib
+dylib:
+	$(MAKE) MAKE_DSYM=$(MAKE_DSYM) CC=$(CC) SWIFTC=$(SWIFTC) \
+		ARCH=$(ARCH) DSYMUTIL=$(DSYMUTIL) \
+		VPATH=$(SRCDIR) -I $(SRCDIR) \
+		-f $(SRCDIR)/Makefile \
+		DYLIB_FILENAME=dylib.dylib \
+		DYLIB_SWIFT_SOURCES=dylib.swift \
+		DYLIB_NAME=dylib \
+		DYLIB_ONLY=YES \
+		SWIFTFLAGS_EXTRAS="-Xcc -I$(SRCDIR)" \
+		C_SOURCES= \
+		LD_EXTRAS="-lSwiftCore -Xlinker -exported_symbol -Xlinker _f" \
+		dylib.dylib
+

lldb/test/API/lang/swift/late_dylib_clangdeps/TestSwiftLateDylibClangDeps.py

@@ -0,0 +1,21 @@
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestSwiftLateDylibClangDeps(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @skipUnlessDarwin
+    @swiftTest
+    @skipIfDarwinEmbedded 
+    def test(self):
+        """Test that a late loaded Swift dylib with Clang dependencies is debuggable"""
+        self.build()
+        target, process, _, _ = lldbutil.run_to_name_breakpoint(self, "main")
+        # Initialize SwiftASTContext before loading the dylib.
+        self.expect("expr -l Swift -- 0")
+        bkpt = target.BreakpointCreateByLocation(lldb.SBFileSpec('dylib.swift'), 5)
+        lldbutil.continue_to_breakpoint(process, bkpt)
+        self.expect("v x", substrs=['42'])
+        self.expect("expr x", substrs=['42'])

lldb/test/API/lang/swift/late_dylib_clangdeps/dylib.swift

@@ -0,0 +1,6 @@
+import ClangMod
+
+@_silgen_name("f") public func f() {
+  let x = FromClang(x: 42)
+  print(x) // line 5
+}

lldb/test/API/lang/swift/late_dylib_clangdeps/loader.c

@@ -0,0 +1,12 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <string.h>
+#include <libgen.h>
+
+int main(int argc, const char **argv) {
+  char *dylib_name = strcat(dirname(argv[0]),"/dylib.dylib");
+  void *dylib = dlopen(dylib_name, RTLD_NOW);
+  void (*f)() = dlsym(dylib, "f");
+  f();
+  return 0;
+}

lldb/test/API/lang/swift/late_dylib_clangdeps/module.modulemap

@@ -0,0 +1,3 @@
+module ClangMod {
+  header "ClangMod.h"
+}