Displaying 2 results from an estimated 2 matches for "caninsertselect".
2017 Jan 24
3
Early legalization pass ? Doing early legalization in an existing pass ?
...likely to prevent optimizations than it is to encourage them.
But I guess I don't follow why things like TTI, TII and TLI queries don't
suffice for this. CodeGenPrepare will break this sequence up. I would
imagine that if the target returns false for isCheapToSpeculateCtlz() and
false for canInsertSelect(), the code would look the way you'd like it to.
But as I said, I'm mostly speculating here and I might be very wrong.
On Mon, Jan 23, 2017 at 5:02 PM, via llvm-dev <llvm-dev at lists.llvm.org>
wrote:
>
> > On Jan 23, 2017, at 4:06 AM, Amaury SECHET via llvm-dev <
>...
2017 Jan 23
2
Early legalization pass ? Doing early legalization in an existing pass ?
Hi all,
Some non trivial legalization of operations which aren't supported by the
backend would benefit from having the optimizer pass on them. I noticed
some example trying to optimize various pieces of code over the past weeks.
One offender is the cttz/ctlz intrinsic when defined on 0. On X86, BSR and
NSF are undefined on 0, and only recent CPU have the LZCNT and TZCNT
instructions that