[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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