Parts of package pgo fetch the line number of a node by parsing the
number out of the string returned from ir.Line().
This is indirect and inefficient, so it should be replaced with a more
direct lookup. It is also potentially buggy: ir.Line uses
ctxt.OutermostPos, i.e., the line number where an inlined node in
inlined. We want ctxt.InnermostPos, because that is the line number used
in pprof profiles that we are matching against (See comments on
OutermostPos and InnermostPos).
I'm not sure whether this was an active, as we use ir.Line before and
during inlining. I think we could see CALL nodes with OutermostPos !=
InnermostPos during midstack inlining, but I am not sure. Regardless,
explicitly using the desired position is clearer.
For #55022.
Change-Id: Ic640761c9e1d01cacbf91f3aaeaf284ad7e38dbd
Reviewed-on: https://go-review.googlesource.com/c/go/+/446302 Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>