Re: [llvm-commits] [llvm] r44858 - in /llvm/trunk: include/llvm/Bitcode/LLVMBitCodes.h include/llvm/DerivedTypes.h include/llvm/GlobalVariable.h include/llvm/Instructions.h lib/AsmParser/LLLexer.cpp lib/AsmParser/llvmAsmParser.y lib/Bitcode/Reader/BitcodeReader.cpp lib/Bitcode/Writer/BitcodeWriter.cpp lib/VMCore/AsmWriter.cpp lib/VMCore/Constants.cpp lib/VMCore/Globals.cpp lib/VMCore/Instructions.cpp lib/VMCore/Type.cpp test/Assembler/2007-12-11-AddressSpaces.ll tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp

[Christopher Lamb]

On Dec 11, 2007, at 4:12 PM, Chris Lattner wrote:
On Dec 11, 2007, at 12:59 AM, Christopher Lamb wrote:

===================================================================== 
=
========
--- llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp (original)
+++ llvm/trunk/lib/Bitcode/Writer/BitcodeWriter.cpp Tue Dec 11
02:59:05 2007
@@ -197,10 +197,14 @@
       TypeVals.push_back(cast<IntegerType>(T)->getBitWidth());
       break;
     case Type::PointerTyID:
+      const PointerType *PTy = cast<PointerType>(T);
+      // POINTER: [pointee type] or [pointee type, address space]
       Code = bitc::TYPE_CODE_POINTER;
+      TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
+      if (unsigned AddressSpace = PTy->getAddressSpace())
+        TypeVals.push_back(AddressSpace);
+      else
+        AbbrevToUse = PtrAbbrev;
       break;

This can be simplified.  In this code, I'd just unconditionally  
emit it:

     case Type::PointerTyID:
+      const PointerType *PTy = cast<PointerType>(T);
+      // POINTER: [pointee type] or [pointee type, address space]
       Code = bitc::TYPE_CODE_POINTER;
+      TypeVals.push_back(VE.getTypeID(PTy->getElementType()));
       TypeVals.push_back(PTy->getAddressSpace());
       AbbrevToUse = PtrAbbrev;
       break;

And change the abbreviation to match, which would apply only if the
addrspace is zero (and thus not encode it at all):

   // Abbrev for TYPE_CODE_POINTER.
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_POINTER));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
                             Log2_32_Ceil(VE.getTypes().size()+1)));
   Abbv->Add(BitCodeAbbrevOp(0));  // Addr space = 0.
   unsigned PtrAbbrev = Stream.EmitAbbrev(Abbv);

The presence of the abbreviation means that any pointers with
addrspace 0 will not need per-instance space to represent this.

This means moving the assert conditional into the if conditional and  
removing the assert in BitstreamWriter.h. Sound OK?

  void EmitAbbreviatedField(const BitCodeAbbrevOp &Op, uintty V) {
    if (Op.isLiteral()) {
      // If the abbrev specifies the literal value to use, don't emit
      // anything.
      assert(V == Op.getLiteralValue() &&
             "Invalid abbrev for record!");
      return;
    }

--
Christopher Lamb



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