Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20201027' into staging

Optimize across branches.
Add logging for cpu_io_recompile.

# gpg: Signature made Tue 27 Oct 2020 16:48:50 GMT
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth-gitlab/tags/pull-tcg-20201027:
  accel/tcg: Add CPU_LOG_EXEC tracing for cpu_io_recompile()
  tcg/optimize: Flush data at labels not TCG_OPF_BB_END
  tcg: Do not kill globals at conditional branches

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>