2 files changed, 24 insertions, 1 deletions
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index f06c61de41..2d994d4b13 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -362,6 +362,20 @@ bool BitcodeReader::ParseAttributeBlock() {
       Attributes RetAttribute = Attribute::None;
       Attributes FnAttribute = Attribute::None;
       for (unsigned i = 0, e = Record.size(); i != e; i += 2) {
+        // FIXME: remove in LLVM 3.0
+        // The alignment is stored as a 16-bit raw value from bits 31--16.
+        // We shift the bits above 31 down by 11 bits.
+
+        unsigned Alignment = (Record[i+1] & (0xffffull << 16)) >> 16;
+        if (Alignment && !isPowerOf2_32(Alignment))
+          return Error("Alignment is not a power of two.");
+
+        Attributes ReconstitutedAttr = Record[i+1] & 0xffff;
+        if (Alignment)
+          ReconstitutedAttr |= Attribute::constructAlignmentFromInt(Alignment);
+        ReconstitutedAttr |= (Record[i+1] & (0xffffull << 32)) >> 11;
+        Record[i+1] = ReconstitutedAttr;
+
         if (Record[i] == 0)
           RetAttribute = Record[i+1];
         else if (Record[i] == ~0U)
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 279e447873..0555ed90f6 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -122,7 +122,16 @@ static void WriteAttributeTable(const ValueEnumerator &VE,
     for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
       const AttributeWithIndex &PAWI = A.getSlot(i);
       Record.push_back(PAWI.Index);
-      Record.push_back(PAWI.Attrs);
+
+      // FIXME: remove in LLVM 3.0
+      // Store the alignment in the bitcode as a 16-bit raw value instead of a
+      // 5-bit log2 encoded value. Shift the bits above the alignment up by
+      // 11 bits.
+      uint64_t FauxAttr = PAWI.Attrs & 0xffff;
+      FauxAttr |= (1ull<<16)<<((PAWI.Attrs & Attribute::Alignment) >> 16);
+      FauxAttr |= (PAWI.Attrs & (0x3FFull << 21)) << 11;
+
+      Record.push_back(FauxAttr);
     }
     
     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);