[llvm-commits] CAST patch: #3: lib/Transforms (except instcombine)

[Reid Spencer]

On Tue, 2006-11-21 at 07:56 -0800, Chris Lattner wrote:
> On Nov 21, 2006, at 12:01 AM, Reid Spencer wrote:

> >> These two casts should just be:
> >>
> >>
> >>            // Always zero extend the value.
> >>                      if (different size)
> >>              SV = new ZExtInst(SV, Old->getType(), SV->getName(),  
> >> SI);
> >>    else
> >>  SV = new BitCast(..)
> >>            if (Offset && Offset < TD.getTypeSize(SV->getType())*8)
> >>              SV = new ShiftInst(Instruction::Shl, SV,
> >>                                 ConstantInt::get(Type::UByteTy,
> >> Offset),
> >>                                 SV->getName()+".adj", SI);
> >>            // Mask out the bits we are about to insert from the old
> >> value.
> >
> > I tried this. It causes ZExt failures. I undid the change. The  
> > might be
> > some cases where sizeof(SV->getType()) == sizeof(Old->getType()).
> 
> In that case, won't the bitcast work?

I'm not sure what was going on there. I checked the size with
getPrimitiveSizeInBits to ensure that SV->getType() was smaller than
Old->getType() before making the zext. Perhaps a bool or pointer or
packed crept in there? I dunnot, but it didn't work.

> 
> -Chris