From 0dc08915d2178be6d265ebc98d01edf8c46e9ab8 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Tue, 12 Feb 2013 08:13:50 +0000
Subject: [PATCH] Have the bitcode writer and reader handle the new attribute
 references.

The bitcode writer emits a reference to the attribute group that the object at
the given index refers to. The bitcode reader is modified to read this in and
map it back to the attribute group.

llvm-svn: 174952
---
 llvm/lib/Bitcode/Reader/BitcodeReader.cpp |  8 +++++++
 llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 36 +++----------------------------
 2 files changed, 11 insertions(+), 33 deletions(-)

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 476c68a..f348843 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -494,6 +494,14 @@ bool BitcodeReader::ParseAttributeBlock() {
       Attrs.clear();
       break;
     }
+    case bitc::PARAMATTR_CODE_ENTRY: { // ENTRY: [attrgrp0, attrgrp1, ...]
+      for (unsigned i = 0, e = Record.size(); i != e; ++i)
+        Attrs.push_back(MAttributeGroups[Record[i]]);
+
+      MAttributes.push_back(AttributeSet::get(Context, Attrs));
+      Attrs.clear();
+      break;
+    }
     }
   }
 }
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 84f67ad..1b73f23 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -209,30 +209,6 @@ static void WriteAttributeGroupTable(const ValueEnumerator &VE,
   Stream.ExitBlock();
 }
 
-/// \brief This returns an integer containing an encoding of all the LLVM
-/// attributes found in the given attribute bitset.  Any change to this encoding
-/// is a breaking change to bitcode compatibility.
-/// N.B. This should be used only by the bitcode writer!
-static uint64_t encodeLLVMAttributesForBitcode(AttributeSet Attrs,
-                                               unsigned Index) {
-  // FIXME: Remove in 4.0!
-
-  // FIXME: It doesn't make sense to store the alignment information as an
-  // expanded out value, we should store it as a log2 value.  However, we can't
-  // just change that here without breaking bitcode compatibility.  If this ever
-  // becomes a problem in practice, we should introduce new tag numbers in the
-  // bitcode file and have those tags use a more efficiently encoded alignment
-  // field.
-
-  // 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 EncodedAttrs = Attrs.Raw(Index) & 0xffff;
-  if (Attrs.hasAttribute(Index, Attribute::Alignment))
-    EncodedAttrs |= Attrs.getParamAlignment(Index) << 16;
-  EncodedAttrs |= (Attrs.Raw(Index) & (0xfffffULL << 21)) << 11;
-  return EncodedAttrs;
-}
-
 static void WriteAttributeTable(const ValueEnumerator &VE,
                                 BitstreamWriter &Stream) {
   const std::vector<AttributeSet> &Attrs = VE.getAttributes();
@@ -240,19 +216,13 @@ static void WriteAttributeTable(const ValueEnumerator &VE,
 
   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 
-  // FIXME: Remove this! It no longer works with the current attributes classes.
-
   SmallVector<uint64_t, 64> Record;
   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
     const AttributeSet &A = Attrs[i];
-    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i) {
-      unsigned Index = A.getSlotIndex(i);
-      Record.push_back(Index);
-      Record.push_back(encodeLLVMAttributesForBitcode(A.getSlotAttributes(i),
-                                                      Index));
-    }
+    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
+      Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
 
-    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY_OLD, Record);
+    Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
     Record.clear();
   }
 
-- 
2.7.4