the pthread stack setup.
* wow64.cc (wow64_revert_to_original_stack): Rephrase some comments.
Return _tlsbase-16 rather than _main_tls-4 so as not to waste stack.
rather than for wincap.is_wow64. Accommodate name change from
wow64_has_64bit_parent to wow64_needs_stack_adjustment. Align comment.
(_dll_crt0): Ditto.
* wincap.h (wincaps::wow64_has_secondary_stack): New element.
* wincap.cc: Implement above element throughout.
(wincapc::init): Set wow64_has_secondary_stack to false on non-64 bit
systems.
* wow64.cc (wow64_needs_stack_adjustment): Rename (hopefully the last
time) from wow64_has_64bit_parent.
(wow64_eval_expected_main_stack): Fix comment to reflect real life.
(wow64_test_for_64bit_parent): Fix comment.
* wow64.h (wow64_needs_stack_adjustment): Accommodate new name.
parent stack fits into the child stack. Align comment.
* wow64.cc (wow64_eval_expected_main_stack): New function to fetch
expected addresses of main thread stack from PE/COFF image header
values.
(wow64_test_for_64bit_parent): Fix comment. Check current stack
against real expected main thread stack addresses.
(wow64_revert_to_original_stack): Fix and add comments. Check memory
against real expected main thread stack addresses. Use orignal stack
if reserved area is >= 256K.
* dcrt0.cc (CYGWIN_GUARD): Drop execute permission for stack, it's
not used for stacks by the OS either.
(child_info_fork::alloc_stack_hard_way): Ditto.
(child_info_fork::alloc_stack): Don't alloc_stack_hard_way under WOW64
if forked from a 64 bit parent. Set child's StackBase to parent's
StackBase. Add comments to explain why.
(wow64_respawn): Move to wow64.cc.
(wow64_started_from_native64): Move to wow64.cc.
(respawn_wow64_process): Move to wow64.cc.
(dll_crt0_0): Drop wow64_test_stack_marker and move stack test into
wow64_test_for_64bit_parent function. Don't return early if WOW64
process has been started from native 64 bit process.
(_dll_crt0): Implement moving stack for WOW64 processes started from
native 64 bit process.
* wow64.cc: New file.
(wow64_has_64bit_parent): Rename from wow64_respawn.
(wow64_test_for_64bit_parent): Rename from wow64_started_from_native64.
Change comment.
(wow64_revert_to_original_stack): New function.
(wow64_respawn_process): Rename from respawn_wow64_process for symmetry.
* wow64.h: New file.
