The .note.GNU-stack section tells the linker that this object does not
require an executable stack.
The .note.GNU-split-stack section tells the linker that functions in
this object can be called directly by split-stack functions, without
require a large stack.
The .note.GNU-no-split-stack section tells the linker that functions
in this object do not have a split-stack prologue.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/198440
From-SVN: r276488
Currently, goroutine switches are implemented with libc
getcontext/setcontext functions, which saves/restores the machine
register states and also the signal context. This does more than
what we need, and performs an expensive syscall.
This CL implements a simplified version of getcontext/setcontext,
in assembly, that only saves/restores the necessary part, i.e.
the callee-save registers, and the PC, SP. A simplified version
of makecontext, written in C, is also added. Currently this is
only implemented on Linux/AMD64.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/178298
From-SVN: r271818
