If the types aren't legal, the expansions may get type legalized in a
different way preventing code sharing. If the type is legal, we will
share some instructions between the two expansions, but we will need an
extra register.
Since we don't appear to fold (neg (sub A, B)) if the sub has an
additional user, I think it makes sense not to expand NABS.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D120513
Default type legalization will create sext_inreg+abs, but we may
not be able to remove the sext_inreg.
Instead this patch expands abs during type legalization to
Y = sraiw X, 31; subw(xor X, Y), Y) which doesn't require the input
to be sign extended.
This gives a big improvement for some neg-abs tests where the
abs is used more than the the neg. Previously the abs was expanded
a different way before and after type legalization. Now they are
expanded in a similar way enabling more CSE.
Reviewed By: asb
Differential Revision: https://reviews.llvm.org/D120636
Add Zbt (ternary) extension code generation to the select lowering
tests since it can have a significant impact on how select is
lowered.
While we are here make the neg-abs commands more consistent with
the other tests.
Reviewed By: lenary
Differential Revision: https://reviews.llvm.org/D94798
We currently don't match this which limits the effectiveness of D91120 until
InstCombine starts canonicalizing to llvm.abs. This should be easy to remove
if/when we remove the SPF_ABS handling.
Differential Revision: https://reviews.llvm.org/D92118
Craig Topper