[PATCH] D103077: [DAGCombine] Poison-prove scalarizeExtractedVectorLoad.

Wed May 26 03:05:42 PDT 2021

uweigand added a comment.

In D103077#2780921 <https://reviews.llvm.org/D103077#2780921>, @jonpa wrote:

> In D103077#2779949 <https://reviews.llvm.org/D103077#2779949>, @fhahn wrote:
>
>> Adjust failing SystemZ test. It would be great if someone familiar with SystemZ could take a look to double-check this makes sense. Perhaps @jonpa?
>
> Yes, this looks like a correct test update to me: the changed immediate operand reflects that now only two shifted bits are inserted into %r1 (instead of all 32).
>
> I wonder what the rationale behind this patch is: if the instruction is poison to begin with, then the program is broken and I don't understand how changing the argument value can change that..?
>
> Adding @uweigand as well just in case...

This looks correct to me as well, it simply implements the mask to valid index (which can be merged into the existing risbgn instruction).

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https://reviews.llvm.org/D103077