[FileSystem] Ignore nanoseconds when comparing oso_mod_time

After a recent change in LLVM the TimePoint encoding become more
precise, exceeding the precision of the TimePoint obtained from the
DebugMap. This patch adds a flag to the GetModificationTime helper in
the FileSystem to return the modification time with less precision.

Thanks to Davide for bisecting this failure on the LLDB bots.

llvm-svn: 347615

3 files changed, 19 insertions, 7 deletions

diff --git a/lldb/include/lldb/Host/FileSystem.h b/lldb/include/lldb/Host/FileSystem.h
index 2122860a5f6..bfc5f93f696 100644
--- a/lldb/include/lldb/Host/FileSystem.h
+++ b/lldb/include/lldb/Host/FileSystem.h
@@ -56,8 +56,12 @@ public:
 
   /// Returns the modification time of the given file.
   /// @{
-  llvm::sys::TimePoint<> GetModificationTime(const FileSpec &file_spec) const;
-  llvm::sys::TimePoint<> GetModificationTime(const llvm::Twine &path) const;
+  llvm::sys::TimePoint<>
+  GetModificationTime(const FileSpec &file_spec,
+                      bool nanosecond_precision = true) const;
+  llvm::sys::TimePoint<>
+  GetModificationTime(const llvm::Twine &path,
+                      bool nanosecond_precision = true) const;
   /// @}
 
   /// Returns the on-disk size of the given file in bytes.
diff --git a/lldb/source/Host/common/FileSystem.cpp b/lldb/source/Host/common/FileSystem.cpp
index a0105997589..db218a3f763 100644
--- a/lldb/source/Host/common/FileSystem.cpp
+++ b/lldb/source/Host/common/FileSystem.cpp
@@ -64,15 +64,22 @@ Optional<FileSystem> &FileSystem::InstanceImpl() {
 }
 
 sys::TimePoint<>
-FileSystem::GetModificationTime(const FileSpec &file_spec) const {
-  return GetModificationTime(file_spec.GetPath());
+FileSystem::GetModificationTime(const FileSpec &file_spec,
+                                bool nanosecond_precision) const {
+  return GetModificationTime(file_spec.GetPath(), nanosecond_precision);
 }
 
-sys::TimePoint<> FileSystem::GetModificationTime(const Twine &path) const {
+sys::TimePoint<>
+FileSystem::GetModificationTime(const Twine &path,
+                                bool nanosecond_precision) const {
   ErrorOr<vfs::Status> status = m_fs->status(path);
   if (!status)
     return sys::TimePoint<>();
-  return status->getLastModificationTime();
+  if (nanosecond_precision)
+    return status->getLastModificationTime();
+  else
+    return std::chrono::time_point_cast<std::chrono::seconds>(
+        status->getLastModificationTime());
 }
 
 uint64_t FileSystem::GetByteSize(const FileSpec &file_spec) const {
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
index 50e27b2f9e4..fa07fd1ebde 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -420,7 +420,8 @@ Module *SymbolFileDWARFDebugMap::GetModuleByCompUnitInfo(
       FileSpec oso_file(oso_path);
       ConstString oso_object;
       if (FileSystem::Instance().Exists(oso_file)) {
-        auto oso_mod_time = FileSystem::Instance().GetModificationTime(oso_file);
+        auto oso_mod_time = FileSystem::Instance().GetModificationTime(
+            oso_file, /*nanosecond_precision=*/false);
         if (oso_mod_time != comp_unit_info->oso_mod_time) {
           obj_file->GetModule()->ReportError(
               "debug map object file '%s' has changed (actual time is "