cmd/link/internal/loadpe: add rudimentary COMDAT support
Add some rudimentary support to the PE file loader for handling
sections in COMDAT when reading host object files. This is needed
in order to link programs with support libraries that are of a more
modern vintage than GCC 5.X.
If a given section XYZ is in COMDAT, the symbol for that section will
be flagged, e.g. section 'Characteristics' field will have the
IMAGE_SCN_LNK_COMDAT bit set, and the symbol will be followed by an
"aux" symbol that includes the COMDAT handling strategy that the
linker needs to use.
This patch supports two COMDAT strategies (IMAGE_COMDAT_SELECT_ANY and
IMAGE_COMDAT_SELECT_SAME_SIZE); more work will have to be done in the
future to support other flavors if it turns out that they are needed.
Updates #35006.
Change-Id: I516e825c30ed3df94ba08323b8a24fb847e10c1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/383835 Reviewed-by: Cherry Mui <cherryyz@google.com>
Trust: Than McIntosh <thanm@google.com>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>