It doesn't.
Fixes 386 build.
While we're here, mark runtime.asmcgocall as GO_ARGS,
so that it will work with stack copying. I don't think anything
that uses it can lead to a stack copy, but better safe than sorry.
Certainly the runtime.asmcgocall_errno variant needs
(and already has) GO_ARGS.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/138400043
The goal here is to commit fully to having precise information
about stack frames. If we need information we don't have,
crash instead of assuming we should scan conservatively.
Since the stack copying assumes fully precise information,
any crashes during garbage collection that are introduced by
this CL are crashes that could have happened during stack
copying instead. Those are harder to find because stacks are
copied much less often than the garbage collector is invoked.
In service of that goal, remove ARGSIZE macros from
asm_*.s, change switchtoM to have no arguments
(it doesn't have any live arguments), and add
args and locals information to some frames that
can call back into Go.
LGTM=khr
R=khr, rlh
CC=golang-codereviews
https://golang.org/cl/137540043
Tests will come in a separate CL after the funcdata stuff is resolved.
Update #8696
LGTM=iant, rsc
R=rsc, iant
CC=golang-codereviews
https://golang.org/cl/138330045
The uses of onM in dopanic/startpanic are okay even from the signal stack.
Fixes#8666.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/134710043
Commit to stack copying for stack growth.
We're carrying around a surprising amount of cruft from older schemes.
I am confident that precise stack scans and stack copying are here to stay.
Delete fallback code for when precise stack info is disabled.
Delete fallback code for when copying stacks is disabled.
Delete fallback code for when StackCopyAlways is disabled.
Delete Stktop chain - there is only one stack segment now.
Delete M.moreargp, M.moreargsize, M.moreframesize, M.cret.
Delete G.writenbuf (unrelated, just dead).
Delete runtime.lessstack, runtime.oldstack.
Delete many amd64 morestack variants.
Delete initialization of morestack frame/arg sizes (shortens split prologue!).
Replace G's stackguard/stackbase/stack0/stacksize/
syscallstack/syscallguard/forkstackguard with simple stack
bounds (lo, hi).
Update liblink, runtime/cgo for adjustments to G.
LGTM=khr
R=khr, bradfitz
CC=golang-codereviews, iant, r
https://golang.org/cl/137410043
