[Modules] In case of lock timeout, fallback and build module
Duncan's r298165 introduced the PCMCache mechanism, which guarantees
that locks aren't necessary anymore for correctness but only for
performance, by avoiding building it twice when possible.
Change the logic to avoid an error but actually build the module in case
the timeout happens. Instead of an error, still emit a remark for
debugging purposes.
rdar://problem/30297862
llvm-svn: 298175
diff --git a/clang/include/clang/Basic/DiagnosticCommonKinds.td b/clang/include/clang/Basic/DiagnosticCommonKinds.td
index b8293f0..98fd3c4 100644
--- a/clang/include/clang/Basic/DiagnosticCommonKinds.td
+++ b/clang/include/clang/Basic/DiagnosticCommonKinds.td
@@ -90,10 +90,10 @@
"module '%0' %select{is incompatible with|requires}1 feature '%2'">;
def err_module_header_missing : Error<
"%select{|umbrella }0header '%1' not found">;
-def err_module_lock_failure : Error<
- "could not acquire lock file for module '%0': %1">, DefaultFatal;
-def err_module_lock_timeout : Error<
- "timed out waiting to acquire lock file for module '%0'">, DefaultFatal;
+def remark_module_lock_failure : Remark<
+ "could not acquire lock file for module '%0': %1">, InGroup<ModuleBuild>;
+def remark_module_lock_timeout : Remark<
+ "timed out waiting to acquire lock file for module '%0'">, InGroup<ModuleBuild>;
def err_module_cycle : Error<"cyclic dependency in module '%0': %1">,
DefaultFatal;
def err_module_prebuilt : Error<
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 4841c10..f660429 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1190,10 +1190,14 @@
llvm::LockFileManager Locked(ModuleFileName);
switch (Locked) {
case llvm::LockFileManager::LFS_Error:
- Diags.Report(ModuleNameLoc, diag::err_module_lock_failure)
+ // PCMCache takes care of correctness and locks are only necessary for
+ // performance. Fallback to building the module in case of any lock
+ // related errors.
+ Diags.Report(ModuleNameLoc, diag::remark_module_lock_failure)
<< Module->Name << Locked.getErrorMessage();
- return false;
-
+ // Clear out any potential leftover.
+ Locked.unsafeRemoveLockFile();
+ // FALLTHROUGH
case llvm::LockFileManager::LFS_Owned:
// We're responsible for building the module ourselves.
if (!compileModuleImpl(ImportingInstance, ModuleNameLoc, Module,
@@ -1213,11 +1217,14 @@
case llvm::LockFileManager::Res_OwnerDied:
continue; // try again to get the lock.
case llvm::LockFileManager::Res_Timeout:
- Diags.Report(ModuleNameLoc, diag::err_module_lock_timeout)
+ // Since PCMCache takes care of correctness, we try waiting for another
+ // process to complete the build so clang does not do it done twice. If
+ // case of timeout, build it ourselves.
+ Diags.Report(ModuleNameLoc, diag::remark_module_lock_timeout)
<< Module->Name;
// Clear the lock file so that future invokations can make progress.
Locked.unsafeRemoveLockFile();
- return false;
+ continue;
}
break;
}