[GlobalISel][AArch64] Make FP constraint checks consider possible use/def banks
In a few places in getInstrMapping, we check if use/def instructions for the
instruction we're mapping have floating point constraints.
We can improve this check and reduce the number of copies in GISel-compiled code
if we make a couple observations:
- For a def instruction, it only matters if the def instruction must always
output a value stored on a FPR
- For a use instruction, it only matters if the use instruction must always
only take in values stored in FPRs
This adds two new functions:
- onlyUsesFP
- onlyDefinesFP
Then we can use those when we're checking the uses/defs instead.
Without this patch, the load, unmerge, store, and select in the added test
would have unnecessary copies.
Differential Revision: https://reviews.llvm.org/D62426
llvm-svn: 361679
3 files changed
