[llvm-commits] [llvm] r101979 - in /llvm/trunk/lib/Target/X86: X86ISelLowering.cpp X86ISelLowering.h X86InstrInfo.td X86Subtarget.cpp X86Subtarget.h

[Evan Cheng]

On Apr 21, 2010, at 1:53 PM, Dan Gohman wrote:

> 
> On Apr 20, 2010, at 6:47 PM, Evan Cheng wrote:
> 
>> Author: evancheng
>> Date: Tue Apr 20 20:47:12 2010
>> New Revision: 101979
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=101979&view=rev
>> Log:
>> isel (i32 anyext i16) as insert_subreg when 16-bit ops are being promoted.
> 
> Hi Evan,
> 
> This invites partial-register updates. Are you sure it's worthwhile?

The idea is when all i16 bits are promoted to i32 these will be coalesced away. There won't be a partial register update issue. One of the problem I see now with -promote-16bit is anyext's are added to read live-in values. That's usually not needed if the sources are promoted in the liveout blocks.

Evan

> 
> Dan
>