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lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp

 //===- NaClBitcodeReader.cpp ----------------------------------------------===//
 //     Internal NaClBitcodeReader implementation
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
@@ skipping 968 matching lines @@
   // PNaCl does not support different DataLayouts in pexes, so we
   // implicitly set the DataLayout to the following default.
   //
   // This is not usually needed by the backend, but it might be used
   // by IR passes that the PNaCl translator runs.  We set this in the
   // reader rather than in pnacl-llc so that 'opt' will also use the
   // correct DataLayout if it is run on a pexe.
   M->setDataLayout("e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-"
                    "f32:32:32-f64:64:64-p:32:32:32-v128:32:32");
 
-  if (InitStream()) return Error(Header.Unsupported());
+  if (InitStream()) return true; // InitSream will set the error string.
 
   // We expect a number of well-defined blocks, though we don't necessarily
   // need to understand them all.
   while (1) {
     if (Stream.AtEndOfStream())
       return false;
 
     NaClBitstreamEntry Entry =
       Stream.advance(NaClBitstreamCursor::AF_DontAutoprocessAbbrevs);
 
@@ skipping 751 matching lines @@
 
   if (Buffer->getBufferSize() & 3)
     return Error("Bitcode stream should be a multiple of 4 bytes in length");
 
   if (Header.Read(BufPtr, BufEnd))
     return Error("Invalid PNaCl bitcode header");
 
   StreamFile.reset(new NaClBitstreamReader(BufPtr, BufEnd));
   Stream.init(*StreamFile);
 
-  return AcceptHeader();
+  if (AcceptHeader())

[jvoung (off chromium), 2013/09/09 23:47:53]

Not quite sure the difference in when "return Error(...)" happens.    Doesn't it
just set a field that will be read later (so doesn't matter too much when it
happens)?

You also have to return a value AcceptHeader() returns no error?

[Derek Schuff, 2013/09/10 18:40:23]

Error just sets a field that will be read later. But Unsupported was only set
when the header is valid but the version is unsupported, so as it was,
InitLazyStream was setting the error on line 1786 but ParseBitcodeInto was
overwriting it. Since InitStream and its callees still set the error, I've kept
this, but also improved the error messages they set.

+    return Error(Header.Unsupported());
 }
 
 bool NaClBitcodeReader::InitLazyStream() {
   StreamingMemoryObject *Bytes = new StreamingMemoryObject(LazyStreamer);
   if (Header.Read(Bytes))
     return Error("Invalid PNaCl bitcode header");
 
   StreamFile.reset(new NaClBitstreamReader(Bytes, Header.getHeaderSize()));
   Stream.init(*StreamFile);
-  return AcceptHeader();
+  if (AcceptHeader())
+    return Error(Header.Unsupported());
 }
 
 //===----------------------------------------------------------------------===//
 // External interface
 //===----------------------------------------------------------------------===//
 
 /// getNaClLazyBitcodeModule - lazy function-at-a-time loading from a file.
 ///
 Module *llvm::getNaClLazyBitcodeModule(MemoryBuffer *Buffer,
                                        LLVMContext& Context,
@@ skipping 54 matching lines @@
   if (M->MaterializeAllPermanently(ErrMsg)) {
     delete M;
     return 0;
   }
 
   // TODO: Restore the use-lists to the in-memory state when the bitcode was
   // written.  We must defer until the Module has been fully materialized.
 
   return M;
 }