[PATCH] SelectionDAG: fold (fp_to_u/sint (u/sint_to_fp val)) when possible

[Quentin Colombet]

On Feb 9, 2015, at 2:35 PM, Fiona Glaser <fglaser at apple.com> wrote:

> 
>> On Feb 9, 2015, at 2:26 PM, Quentin Colombet <qcolombet at apple.com> wrote:
>> 
>> 
>> For the instcombine part:
>> 
>> + if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits())
>> Shouldn’t we have some checks on the DstTy as well?
> 
> Isn’t FITy the DstTy?

Right.

> 
>> 
>> e.g., what happens with:
>> sitofp i32 to float
>> fptoui float to i8
>> 
>> We shouldn’t be able to simplify that with a s/zext, do we… Or maybe we can because it is undef??
> 
> I don’t know :<  Not a language expert here.

Nevermind me, I messed up that FITy was the destination type. This cannot happen.

Regarding the patch itself, the clean-up that Sanjay suggested for the test should land in a separate patch.

Q.

> 
> Done the other parts.
> 
> <floatcvtfold.diff>