Author: Charles Zablit
Date: 2026-07-17T17:32:31+02:00
New Revision: 4671287932028a32caa4bce6aea35f9de3f1daa8

URL: 
https://github.com/llvm/llvm-project/commit/4671287932028a32caa4bce6aea35f9de3f1daa8
DIFF: 
https://github.com/llvm/llvm-project/commit/4671287932028a32caa4bce6aea35f9de3f1daa8.diff

LOG: [lldb][Windows] Reuse preloaded exe module on launch (#210010)

# Brief

Recreating the module everytime causes the path to be canonicalized.
This does not work well with subst drives, because the newly created
module will not have the correct drive path, causing breakpoints to be
unresolved.


# Description
`ProcessWindows::OnDebuggerConnected` derives the executable module from
`GetModuleFileNameExW` on every connect. This returns the process
image's *real* path, so when the target is created via a subst'd or
mapped drive (e.g. `S:\...\a.out`, where `S:` is subst for `C:\S`) it
comes back as `C:\S\...\a.out`. `GetOrCreateModule` then fails to match
the module LLDB had already preloaded and creates a duplicate instead.
The duplicate leaves the original module's breakpoint location orphaned
unresolved while the new module's location is resolved, so a source line
breakpoint reports two locations with only one resolved. Generic tests
that assert exactly one resolved location fail with `"2 != 1"` and
`"Expecting 1 locations, got 2"`.

# Fix
This patch fixes this by first attempting to reuse the existing module
if it exists. In practice, LLDB only looks for the executable during
attach.

This is a problem in Swiftlang where we run our tests with a subst
drive. The impacted tests are:
-
`lang/c/{array_types,function_types,set_values,enum_types,anonymous,forward,local_variables}`
- `lang/cpp/{class_types,inlines}`
- `commands/{apropos/with-process,command/nested_alias,memory/write}`
- `functionalities/{memory/find,dead-strip,memory/holes}`
- `commands/expression/entry-bp`

Added: 
    

Modified: 
    lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp 
b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
index 08a5d24b3db9d..7a196820cf744 100644
--- a/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
+++ b/lldb/source/Plugins/Process/Windows/Common/ProcessWindows.cpp
@@ -645,25 +645,23 @@ void ProcessWindows::OnDebuggerConnected(lldb::addr_t 
image_base) {
   LLDB_LOG(log, "Debugger connected to process {0}.  Image base = {1:x}",
            debugger->GetProcess().GetProcessId(), image_base);
 
-  ModuleSP module;
-  // During attach, we won't have the executable module, so find it now.
-  const DWORD pid = debugger->GetProcess().GetProcessId();
-  const std::string file_name = GetProcessExecutableName(pid);
-  if (file_name.empty()) {
-    return;
-  }
-
-  FileSpec executable_file(file_name);
-  FileSystem::Instance().Resolve(executable_file);
-  ModuleSpec module_spec(executable_file);
-  Status error;
-  module =
-      GetTarget().GetOrCreateModule(module_spec, true /* notify */, &error);
+  ModuleSP module = GetTarget().GetExecutableModule();
   if (!module) {
-    return;
-  }
+    const DWORD pid = debugger->GetProcess().GetProcessId();
+    const std::string file_name = GetProcessExecutableName(pid);
+    if (file_name.empty())
+      return;
 
-  GetTarget().SetExecutableModule(module, eLoadDependentsNo);
+    FileSpec executable_file(file_name);
+    FileSystem::Instance().Resolve(executable_file);
+    ModuleSpec module_spec(executable_file);
+    Status error;
+    module =
+        GetTarget().GetOrCreateModule(module_spec, /*notify=*/true, &error);
+    if (!module)
+      return;
+    GetTarget().SetExecutableModule(module, eLoadDependentsNo);
+  }
 
   if (auto dyld = GetDynamicLoader())
     dyld->OnLoadModule(module, ModuleSpec(), image_base);


        
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