Fix the block stack used by the bitstream cursor.

include/llvm/Bitcode/NaCl/NaClBitCodes.h

 //===- NaClBitCodes.h - Enum values for the bitcode format ------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This header Bitcode enum values.
 //
 // The enum values defined in this file should be considered permanent.  If
 // new features are added, they should have values added at the end of the
 // respective lists.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_BITCODE_NACL_NACLBITCODES_H
 #define LLVM_BITCODE_NACL_NACLBITCODES_H
 
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
+#include <climits>

[Jim Stichnoth, 2016/03/14 22:46:49]

Should includes be sorted?

[Karl, 2016/03/15 20:29:41]

This code was (originally) copied from LLVM, and it wasn't sorted. From what I
can tell, they don't do this in general.  The goal with these files it to create
a little churn as possible, so that it is easier to incorporate upstream changes
in LLVM.

 #include <cassert>
 
 namespace llvm {
 class raw_ostream;
 
 namespace naclbitc {
 enum StandardWidths {
   BlockIDWidth = 8,      // We use VBR-8 for block IDs.
   CodeLenWidth = 4,      // Codelen are VBR-4.
   BlockSizeWidth = 32,   // BlockSize up to 2^32 32-bit words = 16GB per block.
@@ skipping 39 matching lines @@
 
   /// StandardBlockIDs - All bitcode files can optionally include a BLOCKINFO
   /// block, which contains metadata about other blocks in the file.
   enum StandardBlockIDs {
     /// BLOCKINFO_BLOCK is used to define metadata about blocks, for example,
     /// standard abbrevs that should be available to all blocks of a specified
     /// ID.
     BLOCKINFO_BLOCK_ID = 0,
 
     // Block IDs 1-7 are reserved for future expansion.
-    FIRST_APPLICATION_BLOCKID = 8
+    FIRST_APPLICATION_BLOCKID = 8,
+    // Dummy block added around all records in a bitcode file. Allows the code
+    // to treat top-level records like all other records (i.e. all records
+    // appear in a block).
+    TOP_LEVEL_BLOCKID = UINT_MAX

[Derek Schuff, 2016/03/15 17:47:04]

Does it matter that this block will be considered an application block id by
NaClBitcodeBlockDist.cpp and NaClBitcodeCodeDist.cpp?

[Karl, 2016/03/15 20:29:41]

Yes, you are right. It does raise TOP_LEVEL_BLOCKID to an application block.
Moving this to value 7, assuming we will be less likely to get affected by LLVM
changes.

   };
 
   /// BlockInfoCodes - The blockinfo block contains metadata about user-defined
   /// blocks.
   enum BlockInfoCodes {
     // DEFINE_ABBREV has magic semantics here, applying to the current SETBID'd
     // block, instead of the BlockInfo block.
 
     BLOCKINFO_CODE_SETBID        = 1, // SETBID: [blockid#]
                                       // The following two codes were removed
@@ skipping 305 matching lines @@
 
   // Creates a selector range to handle fixed abbrevations up to
   // the specified value.
   explicit NaClBitcodeSelectorAbbrev(unsigned MaxAbbrev)
       : IsFixed(true),
         NumBits(NaClBitsNeededForValue(MaxAbbrev)) {}
 };
 } // End llvm namespace
 
 #endif