This method can be used for allocating resources for registers and/or
arguments, but it can also be used for generic preparation for them
as well. For instance, it can be used to detect some sort of property
of the function signature as a whole (if it's variadic for instance)
which can be stored in position and used to change ABI behavior.
Change-Id: I8a090be65dc4987e35cd115562114cd1b748155f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24106
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This change generalizes the GuestABI Result template family's
allocate() mechanism so that it can also be used with arguments. This
is useful in cases like the 32 bit ARM ISA which says that variadic
functions treat their floating point arguments differently than
non-variadic functions do. This mechanism will give the ABI a chance
to detect that the function is variadic (by checking for VarArgs) and
then to behave differently in that case.
This also makes the GuestABI mechanism a little more regular by
supporting allocate() on both arguments and return values instead of
just return values.
Change-Id: I67050a0ad7ccf15ee75b800dca4eae4fdc0e564e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24103
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Gabe Black <gabeblack@google.com>
It may be necessary to initialize the GuestABI Position type based on
the current state of the thread, for instance by reading the current
stack pointer.
This change makes it possible (but not mandantory) for an ABI to supply
a constructor for Position which accepts a ThreadContext * which it can
use to intiialize itself.
Change-Id: I5609b185f746368c5f9eb2a04074dcafa088f925
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23749
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Some ABIs (including 32 bit ARM, 64 bit x86) allocate their argument
registers differently depending on their return value. For instance,
if the value needs to be returned in memory because it's too big,
the caller could pass a pointer to where the result should be stored
when the function returns. This pointer acts like an invisible first
argument, offsetting where all the normal arguments actually live.
This change adds a mechanism to handle that case. The Result templates
can now declare an allocate() static method which is given a
ThreadContext *, and a reference to the Position object. It can perform
any adjustment it needs to before the normal argument extraction
starts.
Change-Id: Ibda9095f0e8c9882742d24f5effe309ccb514188
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23747
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
