cmd/compile: set prologue_end on every arch

[derekparker]

As of Go 1.11 and commit 7bac2a9 support was added to put information about the end of the function prologue into the produced DWARF information, however it currently only works for x86.

Ideally the DWARF information produced is consistent across arches. In Delve if this information is not present we have to disassemble the function in order to pattern match known function prologues in order to skip them. This is undesirable to say the least and I would like to delete that code.

Opening this issue to track adding prologue_end to the DWARF information produced on every arch.

[derekparker]

cc @heschik @dr2chase @aarzilli

[heschi]

https://golang.org/cl/223297 did part of this. Any more planned for 1.15?

[heschi]

...though that CL isn't merged yet.

[dr2chase]

Any time you want to +2 it....
It would make sense to maybe get ahead on some other architectures, might help gdb, also depends on where delve is going next.

[odeke-em]

The CL got merged on May 13th aka 16 days ago. @dr2chase I shall move this to Go1.16 then.

[dr2chase]

I'm okay with go1.16. Part of the problem is knowing exactly what's right; because of better-user-experience issues, Delve wants it to be someplace that apparently doesn't match what gdb would expect. (My personal user experience with gdb is so terrible that I would never recommend it to a Go user.)

[gopherbot]

Change https://golang.org/cl/266019 mentions this issue: cmd/internal/obj: add prologue_end DWARF stmt for ppc64