This patch addresses PR rtl-optimization/106594, a P1 performance
regression affecting aarch64.

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check, both with and without --target_board=unix{-m32},
with no new failures.

If someone (who can regression test this on aarch64) could take this
from here that would be much appreciated.  Thanks in advance.


2023-03-04  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
        PR rtl-optimization/106594
        * combine.cc (expand_compound_operation): Don't expand/transform
        ZERO_EXTEND or SIGN_EXTEND on targets where rtx_cost claims they are
        cheap.

Roger
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