[PATCH] D128302: [AArch64][CostModel] Detects that ExtractElement at index is not free in AArch64 when result is used as integer.

[David Li via Phabricator via llvm-commits]

davidxl added a comment.

I guess fhahn@ meant that for all useful scenarios, the instruction needs to have some uses (otherwise they are dead).  For this case, the check should probably be tightened : instead of checking if the instruction has uses, it needs to examine the uses and differentiate integer uses that requires a fmov and other use contexts (which makes the extract noop).

Checking use emptiness can pessimize cases where the cost is zero, but it returns non-zero cost.


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  https://reviews.llvm.org/D128302/new/

https://reviews.llvm.org/D128302