Make abbreviations explicit in pnacl-freeze/thaw.

include/llvm/Bitcode/NaCl/NaClBitstreamReader.h

Index: include/llvm/Bitcode/NaCl/NaClBitstreamReader.h
diff --git a/include/llvm/Bitcode/NaCl/NaClBitstreamReader.h b/include/llvm/Bitcode/NaCl/NaClBitstreamReader.h
index 58c0a5d7fa355db91828922fbf45fccab9afcfcd..b75c42f4199ce16331b42702bcda491bf75e2eaf 100644
--- a/include/llvm/Bitcode/NaCl/NaClBitstreamReader.h
+++ b/include/llvm/Bitcode/NaCl/NaClBitstreamReader.h
@@ -186,20 +186,26 @@ class NaClBitstreamCursor {
 
   // CurCodeSize - This is the declared size of code values used for the current
   // block, in bits.
-  unsigned CurCodeSize;
+  int32_t CurCodeSize;

[Karl, 2013/05/17 20:52:18]

Changed to be an instance of NaClBitcodeSelectorAbrev.

 
   /// CurAbbrevs - Abbrevs installed at in this block.
   std::vector<NaClBitCodeAbbrev*> CurAbbrevs;
 
   struct Block {
-    unsigned PrevCodeSize;
+    int32_t PrevCodeSize;

[Karl, 2013/05/17 20:52:18]

Changed to be an instance of NaClBitcodeSelectorAbbrev.

     std::vector<NaClBitCodeAbbrev*> PrevAbbrevs;
-    explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
+    explicit Block(int32_t PCS) : PrevCodeSize(PCS) {}
   };
 
   /// BlockScope - This tracks the codesize of parent blocks.
   SmallVector<Block, 8> BlockScope;
 
+  /// SignedValue - Convert unsigned to corresponding signed value,
+  /// based on the value of IsNegative.
+  int32_t SignedValue(uint32_t Val, bool IsNegative) {

[Karl, 2013/05/17 20:52:18]

Removed, no longer used.

+    int32_t Value = static_cast<int32_t>(Val);
+    return IsNegative ? -Value : Value;
+  }
   
 public:
   NaClBitstreamCursor() : BitStream(0), NextChar(0) {
@@ -442,6 +448,28 @@ public:
     }
   }
 
+  int32_t ReadIntVBR(unsigned NumBits) {

[jvoung (off chromium), 2013/05/14 23:47:14]

Can we just use BitcodeReader::decodeSignRotatedValue(Read...()) ?

[Karl, 2013/05/17 20:52:18]

Removed. Use NaClDecodeSignRotatedValue.

+    // Read extra bit for sign bit, and extract.
+    uint32_t Piece = Read(NumBits+1);
+    bool IsNegative = (Piece & (1U << NumBits)) == (1U << NumBits);
+    Piece &= (1U << (NumBits-1))-1;
+
+    if ((Piece & (1U << (NumBits-1))) == 0)
+      return SignedValue(Piece, IsNegative);
+
+    uint32_t Result = 0;
+    unsigned NextBit = 0;
+    while (1) {
+      Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;
+
+      if ((Piece & (1U << (NumBits-1))) == 0)
+        return SignedValue(Result, IsNegative);
+
+      NextBit += NumBits-1;
+      Piece = Read(NumBits);
+    }
+  }
+
 private:
   void SkipToFourByteBoundary() {
     // If word_t is 64-bits and if we've read less than 32 bits, just dump
@@ -459,7 +487,7 @@ private:
 public:
 
   unsigned ReadCode() {
-    return Read(CurCodeSize);
+    return (CurCodeSize < 0) ? ReadVBR(-CurCodeSize) : Read(CurCodeSize);

[Karl, 2013/05/17 20:52:18]

Changed to:
return CurCodeSize.IsFixed
  ? Read(CurCodeSize.NumBits)
  : ReadVBR(CurCodeSize.NumBits);

   }