The CB[N]Z and TB[N]Z instructions do not expose the comparison through
the condition code flags. This makes it impossible to track speculative
execution through such a branch. We can handle this relatively easily
by simply disabling the patterns in this case.
A side effect of this is that the split patterns for the atomic operations
need to also avoid generating these instructions. They mostly have simple
fall-backs for this already.
* config/aarch64/aarch64.md (cb<optab><mode>1): Disable when
aarch64_track_speculation is true.
(tb<optab><mode>1): Likewise.
* config/aarch64/aarch64.c (aarch64_split_compare_regs): Do not
generate CB[N]Z when tracking speculation.
(aarch64_split_compare_and_swap): Likewise.
(aarch64_split_atomic_op): Likewise.
From-SVN: r263172
