r293393 - Modules: Separate out a checkSignature helper, almost NFC

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

Author: dexonsmith
Date: Sat Jan 28 15:34:28 2017
New Revision: 293393

URL: http://llvm.org/viewvc/llvm-project?rev=293393&view=rev
Log:
Modules: Separate out a checkSignature helper, almost NFC

The main point is to move the delete-the-new-module logic into the same block
that creates it, so I can simplify the memory management in a follow-up, but I
think it's clearer to use use a checkSignature helper here anyway.

There is a minor functionality change: we now scan ahead to pull the signature
out of the control block *only* if this is a new ModuleFile.  For old ones,
ASTReader::ReadControlBlock will have already read the signature.

Modified:
    cfe/trunk/lib/Serialization/ModuleManager.cpp

Modified: cfe/trunk/lib/Serialization/ModuleManager.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ModuleManager.cpp?rev=293393&r1=293392&r2=293393&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ModuleManager.cpp (original)
+++ cfe/trunk/lib/Serialization/ModuleManager.cpp Sat Jan 28 15:34:28 2017
@@ -52,6 +52,17 @@ ModuleManager::lookupBuffer(StringRef Na
   return std::move(InMemoryBuffers[Entry]);
 }
 
+static bool checkSignature(ASTFileSignature Signature,
+                           ASTFileSignature ExpectedSignature,
+                           std::string &ErrorStr) {
+  if (!ExpectedSignature || Signature == ExpectedSignature)
+    return false;
+
+  ErrorStr =
+      Signature ? "signature mismatch" : "could not read module signature";
+  return true;
+}
+
 ModuleManager::AddModuleResult
 ModuleManager::addModule(StringRef FileName, ModuleKind Type,
                          SourceLocation ImportLoc, ModuleFile *ImportedBy,
@@ -136,22 +147,14 @@ ModuleManager::addModule(StringRef FileN
 
     // Initialize the stream.
     ModuleEntry->Data = PCHContainerRdr.ExtractPCH(*ModuleEntry->Buffer);
-  }
 
-  if (ExpectedSignature) {
-    // If we've not read the control block yet, read the signature eagerly now
-    // so that we can check it.
-    if (!ModuleEntry->Signature)
-      ModuleEntry->Signature = ReadSignature(ModuleEntry->Data);
-
-    if (ModuleEntry->Signature != ExpectedSignature) {
-      ErrorStr = ModuleEntry->Signature ? "signature mismatch"
-                                        : "could not read module signature";
-
-      if (NewModule)
-        delete ModuleEntry;
+    // Read the signature eagerly now so that we can check it.
+    if (checkSignature(ReadSignature(ModuleEntry->Data), ExpectedSignature, ErrorStr)) {
+      delete ModuleEntry;
       return OutOfDate;
     }
+  } else if (checkSignature(ModuleEntry->Signature, ExpectedSignature, ErrorStr)) {
+    return OutOfDate;
   }
 
   if (ImportedBy) {