[llvm-commits] [PATCH] Fix PR11334

[Michael Liao]

Typo

On Wed, 2012-07-25 at 13:29 -0700, Michael Liao wrote:
> On Wed, 2012-07-25 at 13:24 -0700, Rotem, Nadav wrote:
> > >>In fact, the real root cause from my understanding is that ISD::FP_EXTEND (including others as well) has the constraint that the input and output vectors must have matching >>element numbers. 'v2f32' is not legal on x86 and there is way to construct a legal FP_EXTEND from
> > >>v2f32 to v2f64. This lead to the scalarization of FP_EXTEND during type legalization. The added optimization is to recover it back and re-construct that extending using a target->>specific without that constrain.
> > 
> > Yes. But you don’t need to reconstruct the vector, if you can handle it before it gets scalarized.  All you have to do is transform the FP_EXTEND node to your own X86ISD node. 
> > The inputs to your ISD nodes would be v4f32, and the output would be v2f64. 
> 
> The optimization is only targeted to optimize the case for FP_EXTEND. In

is not only target to optimize this bug.

> case of a user code constructs the similar pattern, it would be
> optimized as well. Note the extra shuffle node in the patch, if pattern
> constructed including non-identify shuffle (by constructing a series of
> extract elements), it could be optimized as well to construct a shuffle
> followed by a conversion.
> 
> > 
> > >> For <3 x float>, it will be legailized (widened) into v4f32. The test included verified that.
> > 
> > Right, the question is, how important is it to support this type ? Because, if we handle FP_EXTEND before type-legalization, then it would be a bit more difficult to handle this type.
> > 
> 
> <3 x float> is solved as by-product. The main case is to fix <2 x
> float>. If the user code uses <2 x double> for most cases but only
> several places need converting from float. It's better to use <2 x
> float> for that values.
> 
> Yours
> - Michael
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits