Amara Emerson 08b3c0d995 [GlobalISel] Combine G_UMULH x, (1 << c)) -> x >> (bitwidth - c) ...

In order to not generate an unnecessary G_CTLZ, I extended the constant folder
in the CSEMIRBuilder to handle G_CTLZ. I also added some extra handing of
vector constants too. It seems we don't have any support for doing constant
folding of vector constants, so the tests show some other useless G_SUB
instructions too.

Differential Revision: https://reviews.llvm.org/D111036

2021-10-07 23:51:37 -07:00

7.9 KiB

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