[llvm-commits] patch: x86 vector udiv

[Eli Friedman]

On Tue, Nov 1, 2011 at 5:40 PM, Peter Cooper <peter_cooper at apple.com> wrote:
> Hi
>
> Please review this patch for pr8429 to turn vector udiv into vector shrl instructions when dividing by powers of 2.  This was already done on scalars but not on vectors.
>
> I also found that vector shifts were always scalarised on x86 even with SSE on so i turned these into the equivalent intrinsics.

The change to X86ISelLowering.cpp is wrong; the psrld instruction is
not equivalent to ISD::SRL in the general case.

For the rest of the changes, it would be better to handle this
transformation in instcombine.

-Eli