[llvm-commits] [llvm] r51472 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/2008-05-22-FoldAddIVec.ll

[Chris Lattner]

On May 22, 2008, at 9:14 PM, Nick Lewycky wrote:

> Author: nicholas
> Date: Thu May 22 23:14:51 2008
> New Revision: 51472
>
> URL: http://llvm.org/viewvc/llvm-project?rev=51472&view=rev
> Log:
> Implement X + X for vectors.

Is the code generator turning this back into x+x?  If not, this is a  
major pessimization.  What does:

define <4 x i32> @f(<4 x i32> %i) nounwind {
   %A = add <4 x i32> %i, %i
   ret <4 x i32> %A
}

compile into?  Without your patch I get:

_f:
	paddd	%xmm0, %xmm0
	ret

-Chris