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cmd/compile: delay inlinable method compilation for -c=1

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When the concurrent back end is not enabled, it is possible to have a
scenario where: we compile a specific inlinable non-pointer-receiver
method T.M, then at some point later on in the compilation we visit a
type that triggers generation of a pointer-receiver wrapper (*T).M,
which then results in an inline of T.M into (*T).M. This introduces
subtle differences in the DWARF as compared with when the concurrent
back end is enabled (in the concurrent case, by the time we run the
SSA back end on T.M is is marked as being inlined, whereas in the
non-current case it is not marked inlined).

As a fix, at the point where we would normally compile a given
function in the xtop list right away, if the function is a method AND
is inlinable AND hasn't been inlined, then delay its compilation until
compileFunctions (so as to make sure that when we do compile it, all
possible inlining has been complete). In addition, make sure that
the abstract function symbol for the inlined function gets recorded
correctly.

Fixes #38068.

Change-Id: I57410ab5658bd4ee5b4b80750518e9b20fd6ba52
Reviewed-on: https://go-review.googlesource.com/c/go/+/234178
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Than McIntosh 2020-05-15 12:19:07 -04:00
parent 0cfe1fb878
commit fed33d76bc
2 changed files with 31 additions and 2 deletions
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8
src/cmd/internal/obj/objfile.go
View file

@ -788,6 +788,14 @@ func (ft *DwarfFixupTable) SetPrecursorFunc(s *LSym, fn interface{}) {
absfn.Type = objabi.SDWARFINFO
ft.ctxt.Data = append(ft.ctxt.Data, absfn)
// In the case of "late" inlining (inlines that happen during
// wrapper generation as opposed to the main inlining phase) it's
// possible that we didn't cache the abstract function sym for the
// text symbol -- do so now if needed. See issue 38068.
if s.Func != nil && s.Func.dwarfAbsFnSym == nil {
s.Func.dwarfAbsFnSym = absfn
}
ft.precursor[s] = fnState{precursor: fn, absfn: absfn}
}