The GccLto helper library does not contain any code, as its only purpose
is to pull in other libraries that implement intrinsics to which the
linker's codegen pass may emit calls.
So mark it as BTI compatible, so that the linker does not complain about
unannotated objects.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Oliver Smith-Denny <osd@smith-denny.com>
GCC in LTO mode interoperates poorly with non-standard libraries that
provide implementations of compiler intrinsics such as memcpy/memset
or the stack protector entry points. Such libraries need to be built
in non-LTO mode, and then referenced explicitly on the linker command
line using a -plugin-opt=-pass-through=-lxxx linker option.
However, if these intrinsics are also referenced directly, the LTO
version of the code will be pulled in, and will happily satisfy all
other references to the same symbol.
So add a pair of glue libraries, for ARM and AARCH64, that reference
the known intrinsics. Since the binaries live under ArmPkg directly,
we can reference them in tools_def.txt. Under LD garbage collection,
the object itself will be pruned, and so will the intrinsics that end
up unused by the module.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Ard Biesheuvel
Ard Biesheuvel