BitcodeWriter: Refactor common computation of bits required for a type index.

Suggested by Duncan. Happy to bikeshed the name, cache the result, etc.

llvm-svn: 230410

3 files changed, 9 insertions, 4 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index ec43035b22e..26549d59e6d 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -323,7 +323,7 @@ static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
   Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
   SmallVector<uint64_t, 64> TypeVals;
 
-  uint64_t NumBits = Log2_32_Ceil(VE.getTypes().size()+1);
+  uint64_t NumBits = VE.computeBitsRequiredForTypeIndicies();
 
   // Abbrev for TYPE_CODE_POINTER.
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
@@ -2182,7 +2182,7 @@ static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
     BitCodeAbbrev *Abbv = new BitCodeAbbrev();
     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
-                              Log2_32_Ceil(VE.getTypes().size()+1)));
+                              VE.computeBitsRequiredForTypeIndicies()));
     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
                                    Abbv) != CONSTANTS_SETTYPE_ABBREV)
       llvm_unreachable("Unexpected abbrev ordering!");
@@ -2202,7 +2202,7 @@ static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_CE_CAST));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // cast opc
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // typeid
-                              Log2_32_Ceil(VE.getTypes().size()+1)));
+                              VE.computeBitsRequiredForTypeIndicies()));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));    // value id
 
     if (Stream.EmitBlockInfoAbbrev(bitc::CONSTANTS_BLOCK_ID,
@@ -2255,7 +2255,7 @@ static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
     Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_CAST));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));    // OpVal
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,       // dest ty
-                              Log2_32_Ceil(VE.getTypes().size()+1)));
+                              VE.computeBitsRequiredForTypeIndicies()));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4));  // opc
     if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID,
                                    Abbv) != FUNCTION_INST_CAST_ABBREV)
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
index 24b077bbcef..549e94fc96a 100644
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -803,3 +803,7 @@ unsigned ValueEnumerator::getGlobalBasicBlockID(const BasicBlock *BB) const {
   IncorporateFunctionInfoGlobalBBIDs(BB->getParent(), GlobalBasicBlockIDs);
   return getGlobalBasicBlockID(BB);
 }
+
+uint64_t ValueEnumerator::computeBitsRequiredForTypeIndicies() const {
+  return Log2_32_Ceil(getTypes().size() + 1);
+}
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.h b/llvm/lib/Bitcode/Writer/ValueEnumerator.h
index a0681da0880..b94c37039ef 100644
--- a/llvm/lib/Bitcode/Writer/ValueEnumerator.h
+++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.h
@@ -182,6 +182,7 @@ public:
   ///
   void incorporateFunction(const Function &F);
   void purgeFunction();
+  uint64_t computeBitsRequiredForTypeIndicies() const;
 
 private:
   void OptimizeConstants(unsigned CstStart, unsigned CstEnd);