Displaying 3 results from an estimated 3 matches for "shouldreduceloadwidth".
2015 Mar 03
3
[LLVMdev] ReduceLoadWidth, DAGCombiner and non 8bit loads/extloads question.
I'm curious about this code in ReduceLoadWidth (and in DAGCombiner in
general):
if (LegalOperations && !TLI.isLoadExtLegal(ExtType, ExtVT))
return SDValue
<http://llvm.org/docs/doxygen/html/classllvm_1_1SDValue.html>();
LegalOperations is false for the first pre-legalize pass and true for the
post-legalize pass. The first pass is target-independent yes? So that makes
sense.
2015 Mar 03
2
[LLVMdev] ReduceLoadWidth, DAGCombiner and non 8bit loads/extloads question.
...It's crashing because LD1 is produced due to LegalOperations=false in
pre-legalize pass. Then Legalization does not know how to handle it so it
asserts on a default case. I don't know if it's a reasonable expectation or
not but we do not have support for it. I have not tried
overriding shouldReduceLoadWidth.
2) I see, that makes sense to some degree, I'm curious if you can provide
an example? It doesn't seem good to generate something pre-legalize
(target-independent) that you can't then handle when you find that it's
illegal in the very next step that is legalization. I'm guessin...
2015 Mar 04
2
[LLVMdev] ReduceLoadWidth, DAGCombiner and non 8bit loads/extloads question.
...it
> > asserts on a default case.
>
> Yes, and where, and on what, does the assert fire? 8-bit load
> legalization I assume?
>
> > I don't know if it's a reasonable expectation or
> > not but we do not have support for it. I have not tried overriding
> > shouldReduceLoadWidth.
> >
> > 2) I see, that makes sense to some degree, I'm curious if you can
> provide an
> > example? It doesn't seem good to generate something pre-legalize
> > (target-independent) that you can't then handle when you find that it's
> > illegal in th...