[PATCH] D70056: clang/Modules: Split loop in ReadAST between failable and not

[Duncan P. N. Exon Smith via Phabricator via cfe-commits]

dexonsmith created this revision.
dexonsmith added reviewers: aprantl, bruno, Bigcheese.
Herald added a subscriber: ributzka.

Split a loop in ReadAST that visits the just-loaded module chain,
between an initial loop that reads further from the ASTs (and can fail)
and a second loop that does some preloading (and cannot fail).  This
makes it less likely for a reading failure to affect the AST.

This is not fixing a known bug and the behaviour change may not be
observable, it's just part of an audit to look at all of the error
handling in the ASTReader.


https://reviews.llvm.org/D70056

Files:
  clang/lib/Serialization/ASTReader.cpp


Index: clang/lib/Serialization/ASTReader.cpp
===================================================================
--- clang/lib/Serialization/ASTReader.cpp
+++ clang/lib/Serialization/ASTReader.cpp
@@ -4206,7 +4206,8 @@
 
   // Here comes stuff that we only do once the entire chain is loaded.
 
-  // Load the AST blocks of all of the modules that we loaded.
+  // Load the AST blocks of all of the modules that we loaded.  We can still
+  // hit errors parsing the ASTs at this point.
   for (SmallVectorImpl<ImportedModule>::iterator M = Loaded.begin(),
                                               MEnd = Loaded.end();
        M != MEnd; ++M) {
@@ -4227,7 +4228,13 @@
     F.GlobalBitOffset = TotalModulesSizeInBits;
     TotalModulesSizeInBits += F.SizeInBits;
     GlobalBitOffsetsMap.insert(std::make_pair(F.GlobalBitOffset, &F));
+  }
 
+  // Preload source locations and interesting indentifiers.
+  for (SmallVectorImpl<ImportedModule>::iterator M = Loaded.begin(),
+                                              MEnd = Loaded.end();
+       M != MEnd; ++M) {
+    ModuleFile &F = *M->Mod;
     // Preload SLocEntries.
     for (unsigned I = 0, N = F.PreloadSLocEntries.size(); I != N; ++I) {
       int Index = int(F.PreloadSLocEntries[I] - 1) + F.SLocEntryBaseID;


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