[llvm-commits] [llvm] r55085 - in /llvm/trunk: include/llvm/CodeGen/FastISel.h lib/CodeGen/SelectionDAG/FastISel.cpp lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

[Chris Lattner]

On Aug 20, 2008, at 6:21 PM, Evan Cheng wrote:

>>
>> How would converting a multiply into a shift benefit compile time?
>
> It doesn't. This would be a code quality optimization. We want to be
> fast but it doesn't mean generating poor code. :-) We can do some dag
> combiner type optimizations if they are cheap.

For now, it probably isn't worth it to do this sort of thing.

in practice, what we'll want to do for GEPs is try to fold them into  
loads and stores where possible.  This will produce smaller code and  
is probably going to be more significant than mul -> shift for fast  
compiles.

-Chris