This revision was automatically updated to reflect the committed changes.
Closed by commit rG272742a92d24: Perform an extra consistency check when
searching ModuleManager's (authored by aprantl).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D86823/new/
https://reviews.llvm.org/D86823
Files:
clang/lib/Serialization/ModuleManager.cpp
Index: clang/lib/Serialization/ModuleManager.cpp
===================================================================
--- clang/lib/Serialization/ModuleManager.cpp
+++ clang/lib/Serialization/ModuleManager.cpp
@@ -132,15 +132,38 @@
return Missing;
}
+ // The ModuleManager's use of FileEntry nodes as the keys for its map of
+ // loaded modules is less than ideal. Uniqueness for FileEntry nodes is
+ // maintained by FileManager, which in turn uses inode numbers on hosts
+ // that support that. When coupled with the module cache's proclivity for
+ // turning over and deleting stale PCMs, this means entries for different
+ // module files can wind up reusing the same underlying inode. When this
+ // happens, subsequent accesses to the Modules map will disagree on the
+ // ModuleFile associated with a given file. In general, it is not sufficient
+ // to resolve this conundrum with a type like FileEntryRef that stores the
+ // name of the FileEntry node on first access because of path
canonicalization
+ // issues. However, the paths constructed for implicit module builds are
+ // fully under Clang's control. We *can*, therefore, rely on their structure
+ // being consistent across operating systems and across subsequent accesses
+ // to the Modules map.
+ auto implicitModuleNamesMatch = [](ModuleKind Kind, const ModuleFile *MF,
+ const FileEntry *Entry) -> bool {
+ if (Kind != MK_ImplicitModule)
+ return true;
+ return Entry->getName() == MF->FileName;
+ };
+
// Check whether we already loaded this module, before
if (ModuleFile *ModuleEntry = Modules.lookup(Entry)) {
- // Check the stored signature.
- if (checkSignature(ModuleEntry->Signature, ExpectedSignature, ErrorStr))
- return OutOfDate;
-
- Module = ModuleEntry;
- updateModuleImports(*ModuleEntry, ImportedBy, ImportLoc);
- return AlreadyLoaded;
+ if (implicitModuleNamesMatch(Type, ModuleEntry, Entry)) {
+ // Check the stored signature.
+ if (checkSignature(ModuleEntry->Signature, ExpectedSignature, ErrorStr))
+ return OutOfDate;
+
+ Module = ModuleEntry;
+ updateModuleImports(*ModuleEntry, ImportedBy, ImportLoc);
+ return AlreadyLoaded;
+ }
}
// Allocate a new module.
Index: clang/lib/Serialization/ModuleManager.cpp
===================================================================
--- clang/lib/Serialization/ModuleManager.cpp
+++ clang/lib/Serialization/ModuleManager.cpp
@@ -132,15 +132,38 @@
return Missing;
}
+ // The ModuleManager's use of FileEntry nodes as the keys for its map of
+ // loaded modules is less than ideal. Uniqueness for FileEntry nodes is
+ // maintained by FileManager, which in turn uses inode numbers on hosts
+ // that support that. When coupled with the module cache's proclivity for
+ // turning over and deleting stale PCMs, this means entries for different
+ // module files can wind up reusing the same underlying inode. When this
+ // happens, subsequent accesses to the Modules map will disagree on the
+ // ModuleFile associated with a given file. In general, it is not sufficient
+ // to resolve this conundrum with a type like FileEntryRef that stores the
+ // name of the FileEntry node on first access because of path canonicalization
+ // issues. However, the paths constructed for implicit module builds are
+ // fully under Clang's control. We *can*, therefore, rely on their structure
+ // being consistent across operating systems and across subsequent accesses
+ // to the Modules map.
+ auto implicitModuleNamesMatch = [](ModuleKind Kind, const ModuleFile *MF,
+ const FileEntry *Entry) -> bool {
+ if (Kind != MK_ImplicitModule)
+ return true;
+ return Entry->getName() == MF->FileName;
+ };
+
// Check whether we already loaded this module, before
if (ModuleFile *ModuleEntry = Modules.lookup(Entry)) {
- // Check the stored signature.
- if (checkSignature(ModuleEntry->Signature, ExpectedSignature, ErrorStr))
- return OutOfDate;
-
- Module = ModuleEntry;
- updateModuleImports(*ModuleEntry, ImportedBy, ImportLoc);
- return AlreadyLoaded;
+ if (implicitModuleNamesMatch(Type, ModuleEntry, Entry)) {
+ // Check the stored signature.
+ if (checkSignature(ModuleEntry->Signature, ExpectedSignature, ErrorStr))
+ return OutOfDate;
+
+ Module = ModuleEntry;
+ updateModuleImports(*ModuleEntry, ImportedBy, ImportLoc);
+ return AlreadyLoaded;
+ }
}
// Allocate a new module.
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