[PATCH] D78486: [SystemZ] Expand vector zero-extend into a shuffle.

[Jonas Paulsson via Phabricator via llvm-commits]

jonpa added a comment.

About the LCPI vector constants: It seems that those 200 extra constants I noticed were not really due to the optimization of eliminating the zero-vector for PERMUTE. That optimization eliminates 239 VGBMs on SPEC, while adding only 5 more LCPIs. All the other new LCPIs caused by this patch seem to be regular VPERM masks for zero extension that are duplicated once for each function. In other words, I see the same mask in the constant pool with one copy for each function. I looked at this at file scope only (.s / .o), and I am hoping that either that is not a problem, or maybe that the linker optimizes this?

Over night results look good both with and w/out the zero-vector optimization (not much difference).


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https://reviews.llvm.org/D78486