cmd/compile: fix gcSizes.Sizeof for a zero-sized struct

(*gcSizes).Sizeof was requiring the last field of a zero-sized struct to
be at least one byte. But that rule (fix for #9401, see logic in
calcStructOffset) only applies to a struct that has some non-zero sized
fields. Fix (*gcSizes).Sizeof to have the logic like calcStructOffset.

Fixes running the gotests with -G=3 enabled.

Fixes #45390

Change-Id: I011f40e3de3a327392bbbb791b9422be75336313
Reviewed-on: https://go-review.googlesource.com/c/go/+/307549
Reviewed-by: Robert Griesemer <gri@golang.org>
Trust: Dan Scales <danscales@google.com>
This commit is contained in:
Dan Scales 2021-04-05 20:03:02 -07:00
parent 84162b8832
commit 5cd8a34495

View file

@ -115,10 +115,10 @@ func (s *gcSizes) Sizeof(T types2.Type) int64 {
} }
offsets := s.Offsetsof(fields) offsets := s.Offsetsof(fields)
// gc: The last field of a struct is not allowed to // gc: The last field of a non-zero-sized struct is not allowed to
// have size 0. // have size 0.
last := s.Sizeof(fields[n-1].Type()) last := s.Sizeof(fields[n-1].Type())
if last == 0 { if last == 0 && offsets[n-1] > 0 {
last = 1 last = 1
} }