Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20210613' into staging

Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20210613' into staging

Clean up code_gen_buffer allocation.
Add tcg_remove_ops_after.
Fix tcg_constant_* documentation.
Improve TB chaining documentation.
Fix float32_exp2.
Fix arm tcg_out_op function signature.

# gpg: Signature made Mon 14 Jun 2021 02:12:35 BST
# 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-20210613: (34 commits)
  docs/devel: Explain in more detail the TB chaining mechanisms
  softfloat: Fix tp init in float32_exp2
  tcg/arm: Fix tcg_out_op function signature
  tcg: Fix documentation for tcg_constant_* vs tcg_temp_free_*
  tcg: Introduce tcg_remove_ops_after
  tcg: Move tcg_init_ctx and tcg_ctx from accel/tcg/
  tcg: When allocating for !splitwx, begin with PROT_NONE
  tcg: Merge buffer protection and guard page protection
  tcg: Round the tb_size default from qemu_get_host_physmem
  util/osdep: Add qemu_mprotect_rw
  tcg: Sink qemu_madvise call to common code
  tcg: Return the map protection from alloc_code_gen_buffer
  tcg: Allocate code_gen_buffer into struct tcg_region_state
  tcg: Move in_code_gen_buffer and tests to region.c
  tcg: Tidy split_cross_256mb
  tcg: Tidy tcg_n_regions
  tcg: Rename region.start to region.after_prologue
  tcg: Replace region.end with region.total_size
  tcg: Move MAX_CODE_GEN_BUFFER_SIZE to tcg-target.h
  tcg: Introduce tcg_max_ctxs
  ...

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