runtime: add note that Callers never returns an entry PC
The presence of a pc > entry check in CallersFrame implies we might
actually see pc == entry, when in reality Callers will never return such
a PC. This check is actually just a safety check for avoid reporting
completely nonsensical from bad input.
all.bash reports two violations to this invariant:
TestCallersFromWrapper, which explicitly constructs a CallersFrame input
with an entry PC.
runtime/pprof.printStackRecord, which passes pprof stacks to
CallersFrame (technically not a valid use of CallersFrames!).
runtime/pprof.(*Profile).Add can add the entry PC of
runtime/pprof.lostProfileEvent to samples.
(CPU profiles do lostProfileEvent + 1. I will send a second CL to fix
Add.)
Change-Id: Iac2a2f0c15117d4a383bd84cddf0413b2d7dd3ef
Reviewed-on: https://go-review.googlesource.com/c/go/+/634315
Auto-Submit: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>