2 files changed, 14 insertions, 38 deletions

diff --git a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
index a37201e8f4..1646fc8b35 100644
--- a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
+++ b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
@@ -815,17 +815,10 @@ bool NaClBitcodeReader::ParseModule(bool Resume) {
     case naclbitc::MODULE_CODE_VERSION: {  // VERSION: [version#]
       if (Record.size() < 1)
         return Error("Malformed MODULE_CODE_VERSION");
-      // Only version #0 and #1 are supported so far.
+      // Only version #1 is supported for PNaCl. Version #0 is not supported.
       unsigned module_version = Record[0];
-      switch (module_version) {
-        default: return Error("Unknown bitstream version!");
-        case 0:
-          UseRelativeIDs = false;
-          break;
-        case 1:
-          UseRelativeIDs = true;
-          break;
-      }
+      if (module_version != 1)
+        return Error("Unknown bitstream version!");
       break;
     }
     // FUNCTION:  [type, callingconv, isproto, linkage]
@@ -1286,13 +1279,10 @@ bool NaClBitcodeReader::ParseFunctionBody(Function *F) {
 
       for (unsigned i = 0, e = Record.size()-1; i != e; i += 2) {
         Value *V;
-        // With the new function encoding, it is possible that operands have
+        // With relative value IDs, it is possible that operands have
         // negative IDs (for forward references).  Use a signed VBR
         // representation to keep the encoding small.
-        if (UseRelativeIDs)
-          V = getValueSigned(Record, 1+i, NextValueNo);
-        else
-          V = getValue(Record, 1+i, NextValueNo);
+        V = getValueSigned(Record, 1+i, NextValueNo);
         unsigned BBIndex = Record[2+i];
         BasicBlock *BB = getBasicBlock(BBIndex);
         if (!V || !BB) return Error("Invalid PHI record");
diff --git a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.h b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.h
index b6cf9fab80..2e2816f0f1 100644
--- a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.h
+++ b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.h
@@ -188,15 +188,6 @@ class NaClBitcodeReader : public GVMaterializer {
   /// stream.
   DenseMap<Function*, uint64_t> DeferredFunctionInfo;
 
-  /// UseRelativeIDs - Indicates that we are using a new encoding for
-  /// instruction operands where most operands in the current
-  /// FUNCTION_BLOCK are encoded relative to the instruction number,
-  /// for a more compact encoding.  Some instruction operands are not
-  /// relative to the instruction ID: basic block numbers, and types.
-  /// Once the old style function blocks have been phased out, we would
-  /// not need this flag.
-  bool UseRelativeIDs;
-
   /// \brief True if we should only accept supported bitcode format.
   bool AcceptSupportedBitcodeOnly;
 
@@ -209,7 +200,7 @@ public:
     : Context(C), TheModule(0), Buffer(buffer), BufferOwned(false),
       LazyStreamer(0), NextUnreadBit(0), SeenValueSymbolTable(false),
       ValueList(C),
-      SeenFirstFunctionBody(false), UseRelativeIDs(false),
+      SeenFirstFunctionBody(false),
       AcceptSupportedBitcodeOnly(AcceptSupportedOnly),
       IntPtrType(IntegerType::get(C, PNaClIntPtrTypeBitSize)) {
   }
@@ -218,7 +209,7 @@ public:
     : Context(C), TheModule(0), Buffer(0), BufferOwned(false),
       LazyStreamer(streamer), NextUnreadBit(0), SeenValueSymbolTable(false),
       ValueList(C),
-      SeenFirstFunctionBody(false), UseRelativeIDs(false),
+      SeenFirstFunctionBody(false),
       AcceptSupportedBitcodeOnly(AcceptSupportedOnly),
       IntPtrType(IntegerType::get(C, PNaClIntPtrTypeBitSize)) {
   }
@@ -274,10 +265,8 @@ private:
   bool popValue(const SmallVector<uint64_t, 64> &Record, unsigned *Slot,
                 unsigned InstNum, Value **ResVal) {
     if (*Slot == Record.size()) return true;
-    unsigned ValNo = (unsigned)Record[(*Slot)++];
-    // Adjust the ValNo, if it was encoded relative to the InstNum.
-    if (UseRelativeIDs)
-      ValNo = InstNum - ValNo;
+    // ValNo is encoded relative to the InstNum.
+    unsigned ValNo = InstNum - (unsigned)Record[(*Slot)++];
     *ResVal = getFnValueByID(ValNo);
     return *ResVal == 0;
   }
@@ -287,10 +276,8 @@ private:
   Value *getValue(const SmallVector<uint64_t, 64> &Record, unsigned Slot,
                   unsigned InstNum) {
     if (Slot == Record.size()) return 0;
-    unsigned ValNo = (unsigned)Record[Slot];
-    // Adjust the ValNo, if it was encoded relative to the InstNum.
-    if (UseRelativeIDs)
-      ValNo = InstNum - ValNo;
+    // ValNo is encoded relative to the InstNum.
+    unsigned ValNo = InstNum - (unsigned)Record[Slot];
     return getFnValueByID(ValNo);
   }
 
@@ -298,10 +285,9 @@ private:
   Value *getValueSigned(const SmallVector<uint64_t, 64> &Record, unsigned Slot,
                         unsigned InstNum) {
     if (Slot == Record.size()) return 0;
-    unsigned ValNo = (unsigned) NaClDecodeSignRotatedValue(Record[Slot]);
-    // Adjust the ValNo, if it was encoded relative to the InstNum.
-    if (UseRelativeIDs)
-      ValNo = InstNum - ValNo;
+    // ValNo is encoded relative to the InstNum.
+    unsigned ValNo = InstNum -
+        (unsigned) NaClDecodeSignRotatedValue(Record[Slot]);
     return getFnValueByID(ValNo);
   }