[lldb] GetSharedModule: Collect old modules in SmallVector

The various GetSharedModule methods have an optional out parameter for
the old module when a file has changed or been replaced, which the
Target uses to keep its module list current/correct.  We've been using
a single ModuleSP to track "the" old module, and this change switches
to using a SmallVector of ModuleSP, which has a couple benefits:
 - There are multiple codepaths which may discover an old module, and
   this centralizes the code for how to handle multiples in one place,
   in the Target code.  With the single ModuleSP, each place that may
   discover an old module is responsible for how it handles multiples,
   and the current code is inconsistent (some code paths drop the first
   old module, others drop the second).
 - The API will be more natural for identifying old modules in routines
   that work on sets, like ModuleList::ReplaceEquivalent (which I plan
   on updating to report old module(s) in a subsequent change to fix a
   bug).

I'm not convinced we can ever actually run into the case that multiple
old modules are found in the same GetOrCreateModule call, but I think
this change makes sense regardless, in light of the above.

When an old module is reported, Target::GetOrCreateModule calls
m_images.ReplaceModule, which doesn't allow multiple "old" modules; the
new code calls ReplaceModule for the first "old" module, and for any
subsequent old modules it logs the event and calls m_images.Remove.

Reviewed By: jingham

Differential Revision: https://reviews.llvm.org/D89156

(cherry picked from commit 61bfc703c3d36fbefc476cd3829065d983c1c792)

13 files changed, 154 insertions, 101 deletions

diff --git a/lldb/include/lldb/Core/ModuleList.h b/lldb/include/lldb/Core/ModuleList.h
index ae1f6fd..c62021b 100644
--- a/lldb/include/lldb/Core/ModuleList.h
+++ b/lldb/include/lldb/Core/ModuleList.h
@@ -443,12 +443,11 @@ public:
 
   static bool ModuleIsInCache(const Module *module_ptr);
 
-  static Status GetSharedModule(const ModuleSpec &module_spec,
-                                lldb::ModuleSP &module_sp,
-                                const FileSpecList *module_search_paths_ptr,
-                                lldb::ModuleSP *old_module_sp_ptr,
-                                bool *did_create_ptr,
-                                bool always_create = false);
+  static Status
+  GetSharedModule(const ModuleSpec &module_spec, lldb::ModuleSP &module_sp,
+                  const FileSpecList *module_search_paths_ptr,
+                  llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
+                  bool *did_create_ptr, bool always_create = false);
 
   static bool RemoveSharedModule(lldb::ModuleSP &module_sp);
 
diff --git a/lldb/include/lldb/Target/Platform.h b/lldb/include/lldb/Target/Platform.h
index 6234b82..277fcf6 100644
--- a/lldb/include/lldb/Target/Platform.h
+++ b/lldb/include/lldb/Target/Platform.h
@@ -301,11 +301,10 @@ public:
   LocateExecutableScriptingResources(Target *target, Module &module,
                                      Stream *feedback_stream);
 
-  virtual Status GetSharedModule(const ModuleSpec &module_spec,
-                                 Process *process, lldb::ModuleSP &module_sp,
-                                 const FileSpecList *module_search_paths_ptr,
-                                 lldb::ModuleSP *old_module_sp_ptr,
-                                 bool *did_create_ptr);
+  virtual Status GetSharedModule(
+      const ModuleSpec &module_spec, Process *process,
+      lldb::ModuleSP &module_sp, const FileSpecList *module_search_paths_ptr,
+      llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules, bool *did_create_ptr);
 
   virtual bool GetModuleSpec(const FileSpec &module_file_spec,
                              const ArchSpec &arch, ModuleSpec &module_spec);
diff --git a/lldb/source/Core/ModuleList.cpp b/lldb/source/Core/ModuleList.cpp
index 0345678..76a861e 100644
--- a/lldb/source/Core/ModuleList.cpp
+++ b/lldb/source/Core/ModuleList.cpp
@@ -731,11 +731,11 @@ size_t ModuleList::RemoveOrphanSharedModules(bool mandatory) {
   return GetSharedModuleList().RemoveOrphans(mandatory);
 }
 
-Status ModuleList::GetSharedModule(const ModuleSpec &module_spec,
-                                   ModuleSP &module_sp,
-                                   const FileSpecList *module_search_paths_ptr,
-                                   ModuleSP *old_module_sp_ptr,
-                                   bool *did_create_ptr, bool always_create) {
+Status
+ModuleList::GetSharedModule(const ModuleSpec &module_spec, ModuleSP &module_sp,
+                            const FileSpecList *module_search_paths_ptr,
+                            llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
+                            bool *did_create_ptr, bool always_create) {
   ModuleList &shared_module_list = GetSharedModuleList();
   std::lock_guard<std::recursive_mutex> guard(
       shared_module_list.m_modules_mutex);
@@ -747,8 +747,6 @@ Status ModuleList::GetSharedModule(const ModuleSpec &module_spec,
 
   if (did_create_ptr)
     *did_create_ptr = false;
-  if (old_module_sp_ptr)
-    old_module_sp_ptr->reset();
 
   const UUID *uuid_ptr = module_spec.GetUUIDPtr();
   const FileSpec &module_file_spec = module_spec.GetFileSpec();
@@ -769,8 +767,8 @@ Status ModuleList::GetSharedModule(const ModuleSpec &module_spec,
 
         // Make sure the file for the module hasn't been modified
         if (module_sp->FileHasChanged()) {
-          if (old_module_sp_ptr && !*old_module_sp_ptr)
-            *old_module_sp_ptr = module_sp;
+          if (old_modules)
+            old_modules->push_back(module_sp);
 
           Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_MODULES));
           if (log != nullptr)
@@ -924,8 +922,8 @@ Status ModuleList::GetSharedModule(const ModuleSpec &module_spec,
             located_binary_modulespec.GetFileSpec());
         if (file_spec_mod_time != llvm::sys::TimePoint<>()) {
           if (file_spec_mod_time != module_sp->GetModificationTime()) {
-            if (old_module_sp_ptr)
-              *old_module_sp_ptr = module_sp;
+            if (old_modules)
+              old_modules->push_back(module_sp);
             shared_module_list.Remove(module_sp);
             module_sp.reset();
           }
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index f5ec08a..133eda9 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -221,7 +221,7 @@ BringInRemoteFile(Platform *platform,
 lldb_private::Status PlatformDarwin::GetSharedModuleWithLocalCache(
     const lldb_private::ModuleSpec &module_spec, lldb::ModuleSP &module_sp,
     const lldb_private::FileSpecList *module_search_paths_ptr,
-    lldb::ModuleSP *old_module_sp_ptr, bool *did_create_ptr) {
+    llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules, bool *did_create_ptr) {
 
   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PLATFORM));
   LLDB_LOGF(log,
@@ -238,7 +238,7 @@ lldb_private::Status PlatformDarwin::GetSharedModuleWithLocalCache(
   Status err;
 
   err = ModuleList::GetSharedModule(module_spec, module_sp,
-                                    module_search_paths_ptr, old_module_sp_ptr,
+                                    module_search_paths_ptr, old_modules,
                                     did_create_ptr);
   if (module_sp)
     return err;
@@ -341,8 +341,8 @@ lldb_private::Status PlatformDarwin::GetSharedModuleWithLocalCache(
 
 Status PlatformDarwin::GetSharedModule(
     const ModuleSpec &module_spec, Process *process, ModuleSP &module_sp,
-    const FileSpecList *module_search_paths_ptr, ModuleSP *old_module_sp_ptr,
-    bool *did_create_ptr) {
+    const FileSpecList *module_search_paths_ptr,
+    llvm::SmallVectorImpl<ModuleSP> *old_modules, bool *did_create_ptr) {
   Status error;
   module_sp.reset();
 
@@ -351,16 +351,16 @@ Status PlatformDarwin::GetSharedModule(
     // module first.
     if (m_remote_platform_sp) {
       error = m_remote_platform_sp->GetSharedModule(
-          module_spec, process, module_sp, module_search_paths_ptr,
-          old_module_sp_ptr, did_create_ptr);
+          module_spec, process, module_sp, module_search_paths_ptr, old_modules,
+          did_create_ptr);
     }
   }
 
   if (!module_sp) {
     // Fall back to the local platform and find the file locally
     error = Platform::GetSharedModule(module_spec, process, module_sp,
-                                      module_search_paths_ptr,
-                                      old_module_sp_ptr, did_create_ptr);
+                                      module_search_paths_ptr, old_modules,
+                                      did_create_ptr);
 
     const FileSpec &platform_file = module_spec.GetFileSpec();
     if (!module_sp && module_search_paths_ptr && platform_file) {
@@ -373,7 +373,7 @@ Status PlatformDarwin::GetSharedModule(
           new_module_spec.GetFileSpec() = bundle_directory;
           if (Host::ResolveExecutableInBundle(new_module_spec.GetFileSpec())) {
             Status new_error(Platform::GetSharedModule(
-                new_module_spec, process, module_sp, nullptr, old_module_sp_ptr,
+                new_module_spec, process, module_sp, nullptr, old_modules,
                 did_create_ptr));
 
             if (module_sp)
@@ -400,8 +400,8 @@ Status PlatformDarwin::GetSharedModule(
                 ModuleSpec new_module_spec(module_spec);
                 new_module_spec.GetFileSpec() = new_file_spec;
                 Status new_error(Platform::GetSharedModule(
-                    new_module_spec, process, module_sp, nullptr,
-                    old_module_sp_ptr, did_create_ptr));
+                    new_module_spec, process, module_sp, nullptr, old_modules,
+                    did_create_ptr));
 
                 if (module_sp) {
                   module_sp->SetPlatformFileSpec(new_file_spec);
@@ -1639,8 +1639,8 @@ PlatformDarwin::LaunchProcess(lldb_private::ProcessLaunchInfo &launch_info) {
 
 lldb_private::Status PlatformDarwin::FindBundleBinaryInExecSearchPaths(
     const ModuleSpec &module_spec, Process *process, ModuleSP &module_sp,
-    const FileSpecList *module_search_paths_ptr, ModuleSP *old_module_sp_ptr,
-    bool *did_create_ptr) {
+    const FileSpecList *module_search_paths_ptr,
+    llvm::SmallVectorImpl<ModuleSP> *old_modules, bool *did_create_ptr) {
   const FileSpec &platform_file = module_spec.GetFileSpec();
   // See if the file is present in any of the module_search_paths_ptr
   // directories.
@@ -1697,9 +1697,9 @@ lldb_private::Status PlatformDarwin::FindBundleBinaryInExecSearchPaths(
         if (FileSystem::Instance().Exists(path_to_try)) {
           ModuleSpec new_module_spec(module_spec);
           new_module_spec.GetFileSpec() = path_to_try;
-          Status new_error(Platform::GetSharedModule(
-              new_module_spec, process, module_sp, nullptr, old_module_sp_ptr,
-              did_create_ptr));
+          Status new_error(
+              Platform::GetSharedModule(new_module_spec, process, module_sp,
+                                        nullptr, old_modules, did_create_ptr));
 
           if (module_sp) {
             module_sp->SetPlatformFileSpec(path_to_try);
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
index 8e28a70..4e9a949 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
@@ -46,7 +46,7 @@ public:
   GetSharedModule(const lldb_private::ModuleSpec &module_spec,
                   lldb_private::Process *process, lldb::ModuleSP &module_sp,
                   const lldb_private::FileSpecList *module_search_paths_ptr,
-                  lldb::ModuleSP *old_module_sp_ptr,
+                  llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
                   bool *did_create_ptr) override;
 
   size_t GetSoftwareBreakpointTrapOpcode(
@@ -132,7 +132,7 @@ protected:
   virtual lldb_private::Status GetSharedModuleWithLocalCache(
       const lldb_private::ModuleSpec &module_spec, lldb::ModuleSP &module_sp,
       const lldb_private::FileSpecList *module_search_paths_ptr,
-      lldb::ModuleSP *old_module_sp_ptr, bool *did_create_ptr);
+      llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules, bool *did_create_ptr);
 
   struct SDKEnumeratorInfo {
     lldb_private::FileSpec found_path;
@@ -158,7 +158,7 @@ protected:
       const lldb_private::ModuleSpec &module_spec,
       lldb_private::Process *process, lldb::ModuleSP &module_sp,
       const lldb_private::FileSpecList *module_search_paths_ptr,
-      lldb::ModuleSP *old_module_sp_ptr, bool *did_create_ptr);
+      llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules, bool *did_create_ptr);
 
   static std::string FindComponentInPath(llvm::StringRef path,
                                          llvm::StringRef component);
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
index f6c0f26..79cbc94 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
@@ -644,8 +644,8 @@ bool PlatformDarwinKernel::KernelHasdSYMSibling(const FileSpec &kernel_binary) {
 
 Status PlatformDarwinKernel::GetSharedModule(
     const ModuleSpec &module_spec, Process *process, ModuleSP &module_sp,
-    const FileSpecList *module_search_paths_ptr, ModuleSP *old_module_sp_ptr,
-    bool *did_create_ptr) {
+    const FileSpecList *module_search_paths_ptr,
+    llvm::SmallVectorImpl<ModuleSP> *old_modules, bool *did_create_ptr) {
   Status error;
   module_sp.reset();
   const FileSpec &platform_file = module_spec.GetFileSpec();
@@ -676,7 +676,7 @@ Status PlatformDarwinKernel::GetSharedModule(
     // framework on macOS systems, a chance.
     error = PlatformDarwin::GetSharedModule(module_spec, process, module_sp,
                                            module_search_paths_ptr,
-                                           old_module_sp_ptr, did_create_ptr);
+                                           old_modules, did_create_ptr);
     if (error.Success() && module_sp.get()) {
       return error;
     }
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.h b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.h
index 9cf9e41..203bfb5 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.h
@@ -57,7 +57,7 @@ public:
   GetSharedModule(const lldb_private::ModuleSpec &module_spec,
                   lldb_private::Process *process, lldb::ModuleSP &module_sp,
                   const lldb_private::FileSpecList *module_search_paths_ptr,
-                  lldb::ModuleSP *old_module_sp_ptr,
+                  llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
                   bool *did_create_ptr) override;
 
   bool GetSupportedArchitectureAtIndex(uint32_t idx,
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.cpp
index 0b7f898e..cbdd2cd 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.cpp
@@ -292,10 +292,10 @@ lldb_private::Status PlatformMacOSX::GetSharedModule(
     const lldb_private::ModuleSpec &module_spec, Process *process,
     lldb::ModuleSP &module_sp,
     const lldb_private::FileSpecList *module_search_paths_ptr,
-    lldb::ModuleSP *old_module_sp_ptr, bool *did_create_ptr) {
-  Status error = GetSharedModuleWithLocalCache(
-      module_spec, module_sp, module_search_paths_ptr, old_module_sp_ptr,
-      did_create_ptr);
+    llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules, bool *did_create_ptr) {
+  Status error = GetSharedModuleWithLocalCache(module_spec, module_sp,
+                                               module_search_paths_ptr,
+                                               old_modules, did_create_ptr);
 
   if (module_sp) {
     if (module_spec.GetArchitecture().GetCore() ==
@@ -306,15 +306,16 @@ lldb_private::Status PlatformMacOSX::GetSharedModule(
         ModuleSpec module_spec_x86_64(module_spec);
         module_spec_x86_64.GetArchitecture() = ArchSpec("x86_64-apple-macosx");
         lldb::ModuleSP x86_64_module_sp;
-        lldb::ModuleSP old_x86_64_module_sp;
+        llvm::SmallVector<lldb::ModuleSP, 1> old_x86_64_modules;
         bool did_create = false;
         Status x86_64_error = GetSharedModuleWithLocalCache(
             module_spec_x86_64, x86_64_module_sp, module_search_paths_ptr,
-            &old_x86_64_module_sp, &did_create);
+            &old_x86_64_modules, &did_create);
         if (x86_64_module_sp && x86_64_module_sp->GetObjectFile()) {
           module_sp = x86_64_module_sp;
-          if (old_module_sp_ptr)
-            *old_module_sp_ptr = old_x86_64_module_sp;
+          if (old_modules)
+            old_modules->append(old_x86_64_modules.begin(),
+                                old_x86_64_modules.end());
           if (did_create_ptr)
             *did_create_ptr = did_create;
           return x86_64_error;
@@ -324,7 +325,9 @@ lldb_private::Status PlatformMacOSX::GetSharedModule(
   }
 
   if (!module_sp) {
-      error = FindBundleBinaryInExecSearchPaths (module_spec, process, module_sp, module_search_paths_ptr, old_module_sp_ptr, did_create_ptr);
+    error = FindBundleBinaryInExecSearchPaths(module_spec, process, module_sp,
+                                              module_search_paths_ptr,
+                                              old_modules, did_create_ptr);
   }
   return error;
 }
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.h b/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.h
index 30b11eb..deca3f0 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformMacOSX.h
@@ -40,7 +40,7 @@ public:
   GetSharedModule(const lldb_private::ModuleSpec &module_spec,
                   lldb_private::Process *process, lldb::ModuleSP &module_sp,
                   const lldb_private::FileSpecList *module_search_paths_ptr,
-                  lldb::ModuleSP *old_module_sp_ptr,
+                  llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
                   bool *did_create_ptr) override;
 
   const char *GetDescription() override {
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.cpp
index e4ede0d..065eefa 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.cpp
@@ -504,8 +504,8 @@ Status PlatformRemoteDarwinDevice::GetSymbolFile(const FileSpec &platform_file,
 
 Status PlatformRemoteDarwinDevice::GetSharedModule(
     const ModuleSpec &module_spec, Process *process, ModuleSP &module_sp,
-    const FileSpecList *module_search_paths_ptr, ModuleSP *old_module_sp_ptr,
-    bool *did_create_ptr) {
+    const FileSpecList *module_search_paths_ptr,
+    llvm::SmallVectorImpl<ModuleSP> *old_modules, bool *did_create_ptr) {
   // For iOS, the SDK files are all cached locally on the host system. So first
   // we ask for the file in the cached SDK, then we attempt to get a shared
   // module for the right architecture with the right UUID.
@@ -608,24 +608,25 @@ Status PlatformRemoteDarwinDevice::GetSharedModule(
   // This may not be an SDK-related module.  Try whether we can bring in the
   // thing to our local cache.
   error = GetSharedModuleWithLocalCache(module_spec, module_sp,
-                                        module_search_paths_ptr,
-                                        old_module_sp_ptr, did_create_ptr);
+                                        module_search_paths_ptr, old_modules,
+                                        did_create_ptr);
   if (error.Success())
     return error;
 
   // See if the file is present in any of the module_search_paths_ptr
   // directories.
   if (!module_sp)
-    error = PlatformDarwin::FindBundleBinaryInExecSearchPaths (module_spec, process, module_sp,
-            module_search_paths_ptr, old_module_sp_ptr, did_create_ptr);
+    error = PlatformDarwin::FindBundleBinaryInExecSearchPaths(
+        module_spec, process, module_sp, module_search_paths_ptr, old_modules,
+        did_create_ptr);
 
   if (error.Success())
     return error;
 
   const bool always_create = false;
-  error = ModuleList::GetSharedModule(
-      module_spec, module_sp, module_search_paths_ptr, old_module_sp_ptr,
-      did_create_ptr, always_create);
+  error = ModuleList::GetSharedModule(module_spec, module_sp,
+                                      module_search_paths_ptr, old_modules,
+                                      did_create_ptr, always_create);
 
   if (module_sp)
     module_sp->SetPlatformFileSpec(platform_file);
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.h b/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.h
index b1b760f..cc5f286 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformRemoteDarwinDevice.h
@@ -38,7 +38,7 @@ public:
   GetSharedModule(const lldb_private::ModuleSpec &module_spec,
                   lldb_private::Process *process, lldb::ModuleSP &module_sp,
                   const lldb_private::FileSpecList *module_search_paths_ptr,
-                  lldb::ModuleSP *old_module_sp_ptr,
+                  llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
                   bool *did_create_ptr) override;
 
   void
diff --git a/lldb/source/Target/Platform.cpp b/lldb/source/Target/Platform.cpp
index 34ed787..e5afb4c 100644
--- a/lldb/source/Target/Platform.cpp
+++ b/lldb/source/Target/Platform.cpp
@@ -218,15 +218,14 @@ Platform::LocateExecutableScriptingResources(Target *target, Module &module,
 //    return PlatformSP();
 //}
 
-Status Platform::GetSharedModule(const ModuleSpec &module_spec,
-                                 Process *process, ModuleSP &module_sp,
-                                 const FileSpecList *module_search_paths_ptr,
-                                 ModuleSP *old_module_sp_ptr,
-                                 bool *did_create_ptr) {
+Status Platform::GetSharedModule(
+    const ModuleSpec &module_spec, Process *process, ModuleSP &module_sp,
+    const FileSpecList *module_search_paths_ptr,
+    llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules, bool *did_create_ptr) {
   if (IsHost())
-    return ModuleList::GetSharedModule(
-        module_spec, module_sp, module_search_paths_ptr, old_module_sp_ptr,
-        did_create_ptr, false);
+    return ModuleList::GetSharedModule(module_spec, module_sp,
+                                       module_search_paths_ptr, old_modules,
+                                       did_create_ptr, false);
 
   // Module resolver lambda.
   auto resolver = [&](const ModuleSpec &spec) {
@@ -239,17 +238,17 @@ Status Platform::GetSharedModule(const ModuleSpec &module_spec,
       resolved_spec.GetFileSpec().PrependPathComponent(
           m_sdk_sysroot.GetStringRef());
       // Try to get shared module with resolved spec.
-      error = ModuleList::GetSharedModule(
-          resolved_spec, module_sp, module_search_paths_ptr, old_module_sp_ptr,
-          did_create_ptr, false);
+      error = ModuleList::GetSharedModule(resolved_spec, module_sp,
+                                          module_search_paths_ptr, old_modules,
+                                          did_create_ptr, false);
     }
     // If we don't have sysroot or it didn't work then
     // try original module spec.
     if (!error.Success()) {
       resolved_spec = spec;
-      error = ModuleList::GetSharedModule(
-          resolved_spec, module_sp, module_search_paths_ptr, old_module_sp_ptr,
-          did_create_ptr, false);
+      error = ModuleList::GetSharedModule(resolved_spec, module_sp,
+                                          module_search_paths_ptr, old_modules,
+                                          did_create_ptr, false);
     }
     if (error.Success() && module_sp)
       module_sp->SetPlatformFileSpec(resolved_spec.GetFileSpec());
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index 707344f..19d0c3d 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -1965,8 +1965,9 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &module_spec, bool notify,
     module_sp = m_images.FindFirstModule(module_spec);
 
   if (!module_sp) {
-    ModuleSP old_module_sp; // This will get filled in if we have a new version
-                            // of the library
+    llvm::SmallVector<ModuleSP, 1>
+        old_modules; // This will get filled in if we have a new version
+                     // of the library
     bool did_create_module = false;
     FileSpecList search_paths = GetExecutableSearchPaths();
     // If there are image search path entries, try to use them first to acquire
@@ -1979,7 +1980,7 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &module_spec, bool notify,
         transformed_spec.GetFileSpec().GetFilename() =
             module_spec.GetFileSpec().GetFilename();
         error = ModuleList::GetSharedModule(transformed_spec, module_sp,
-                                            &search_paths, &old_module_sp,
+                                            &search_paths, &old_modules,
                                             &did_create_module);
       }
     }
@@ -1997,7 +1998,7 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &module_spec, bool notify,
         // We have a UUID, it is OK to check the global module list...
         error =
             ModuleList::GetSharedModule(module_spec, module_sp, &search_paths,
-                                        &old_module_sp, &did_create_module);
+                                        &old_modules, &did_create_module);
       }
 
       if (!module_sp) {
@@ -2006,7 +2007,7 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &module_spec, bool notify,
         if (m_platform_sp) {
           error = m_platform_sp->GetSharedModule(
               module_spec, m_process_sp.get(), module_sp, &search_paths,
-              &old_module_sp, &did_create_module);
+              &old_modules, &did_create_module);
         } else {
           error.SetErrorString("no platform is currently set");
         }
@@ -2057,18 +2058,18 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &module_spec, bool notify,
         // this target. So let's remove the UUID from the module list, and look
         // in the target's module list. Only do this if there is SOMETHING else
         // in the module spec...
-        if (!old_module_sp) {
-          if (module_spec.GetUUID().IsValid() &&
-              !module_spec.GetFileSpec().GetFilename().IsEmpty() &&
-              !module_spec.GetFileSpec().GetDirectory().IsEmpty()) {
-            ModuleSpec module_spec_copy(module_spec.GetFileSpec());
-            module_spec_copy.GetUUID().Clear();
-
-            ModuleList found_modules;
-            m_images.FindModules(module_spec_copy, found_modules);
-            if (found_modules.GetSize() == 1)
-              old_module_sp = found_modules.GetModuleAtIndex(0);
-          }
+        if (module_spec.GetUUID().IsValid() &&
+            !module_spec.GetFileSpec().GetFilename().IsEmpty() &&
+            !module_spec.GetFileSpec().GetDirectory().IsEmpty()) {
+          ModuleSpec module_spec_copy(module_spec.GetFileSpec());
+          module_spec_copy.GetUUID().Clear();
+
+          ModuleList found_modules;
+          m_images.FindModules(module_spec_copy, found_modules);
+          found_modules.ForEach([&](const ModuleSP &found_module) -> bool {
+            old_modules.push_back(found_module);
+            return true;
+          });
         }
 
         // Preload symbols outside of any lock, so hopefully we can do this for
@@ -2076,14 +2077,67 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &module_spec, bool notify,
         if (GetPreloadSymbols())
           module_sp->PreloadSymbols();
 
-        if (old_module_sp && m_images.GetIndexForModule(old_module_sp.get()) !=
-                                 LLDB_INVALID_INDEX32) {
-          m_images.ReplaceModule(old_module_sp, module_sp);
+        llvm::SmallVector<ModuleSP, 1> replaced_modules;
+        for (ModuleSP &old_module_sp : old_modules) {
+          if (m_images.GetIndexForModule(old_module_sp.get()) !=
+              LLDB_INVALID_INDEX32) {
+            if (replaced_modules.empty())
+              m_images.ReplaceModule(old_module_sp, module_sp);
+            else
+              m_images.Remove(old_module_sp);
+
+            replaced_modules.push_back(std::move(old_module_sp));
+          }
+        }
+
+        if (replaced_modules.size() > 1) {
+          // The same new module replaced multiple old modules
+          // simultaneously.  It's not clear this should ever
+          // happen (if we always replace old modules as we add
+          // new ones, presumably we should never have more than
+          // one old one).  If there are legitimate cases where
+          // this happens, then the ModuleList::Notifier interface
+          // may need to be adjusted to allow reporting this.
+          // In the meantime, just log that this has happened; just
+          // above we called ReplaceModule on the first one, and Remove
+          // on the rest.
+          if (Log *log = GetLogIfAnyCategoriesSet(LIBLLDB_LOG_TARGET |
+                                                  LIBLLDB_LOG_MODULES)) {
+            StreamString message;
+            auto dump = [&message](Module &dump_module) -> void {
+              UUID dump_uuid = dump_module.GetUUID();
+
+              message << '[';
+              dump_module.GetDescription(message.AsRawOstream());
+              message << " (uuid ";
+
+              if (dump_uuid.IsValid())
+                dump_uuid.Dump(&message);
+              else
+                message << "not specified";
+
+              message << ")]";
+            };
+
+            message << "New module ";
+            dump(*module_sp);
+            message.AsRawOstream()
+                << llvm::formatv(" simultaneously replaced {0} old modules: ",
+                                 replaced_modules.size());
+            for (ModuleSP &replaced_module_sp : replaced_modules)
+              dump(*replaced_module_sp);
+
+            log->PutString(message.GetString());
+          }
+        }
+
+        if (replaced_modules.empty())
+          m_images.Append(module_sp, notify);
+
+        for (ModuleSP &old_module_sp : replaced_modules) {
           Module *old_module_ptr = old_module_sp.get();
           old_module_sp.reset();
           ModuleList::RemoveSharedModuleIfOrphaned(old_module_ptr);
-        } else {
-          m_images.Append(module_sp, notify);
         }
       } else
         module_sp.reset();