This patch adds a CFI entry for each SVE callee saved register
that needs unwind info at an offset from the CFA. The offset is
a DWARF expression because the offset is partly scalable.
The CFI entries only cover a subset of the SVE callee-saves and
only encodes the lower 64-bits, thus implementing the lowest
common denominator ABI. Existing unwinders may support VG but
only restore the lower 64-bits.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D84044
The CFA is calculated as (SP/FP + offset), but when there are
SVE objects on the stack the SP offset is partly scalable and
should instead be expressed as the DWARF expression:
SP + offset + scalable_offset * VG
where VG is the Vector Granule register, containing the
number of 64bits 'granules' in a scalable vector.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D84043
While deallocating the stackframe, the offset used to reload the
callee-saved registers was not pointing to the SVE callee-saves,
but rather to the whole SVE area.
+--------------+
| GRP callee |
| saves |
+--------------+ <- FP
| SVE callee |
| saves |
+--------------+ <- Should restore SVE callee saves from here
| SVE Spills |
| and Locals |
+--------------+ <- instead of from here.
| |
: :
| |
+--------------+ <- SP
Reviewed By: paulwalker-arm
Differential Revision: https://reviews.llvm.org/D84539
Instead of aligning the last callee-saved-register slot to the stack
alignment (16 bytes), just align the SVE callee-saved block. This also
simplifies the code that allocates space for the callee-saves.
This change is needed to make sure the offset to which the callee-saved
register is spilled, corresponds to the offset used for e.g. unwind call
frame instructions.
Reviewers: efriedma, paulwalker-arm, david-arm, rengolin
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D84042
Fixed stack objects are preallocated and defined to be allocated before
any of the regular stack objects. These are normally used to model stack
arguments.
The AAPCS does not support passing SVE registers on the stack by value
(only by reference). The current layout also doesn't place them before
all stack objects, but rather before all SVE objects. Removing this
simplifies the code that emits the allocation/deallocation
around callee-saved registers (D84042).
This patch also removes all uses of fixedStack from from
framelayout-sve.mir, where this was used purely for testing purposes.
Reviewers: paulwalker-arm, efriedma, rengolin
Reviewed By: paulwalker-arm
Differential Revision: https://reviews.llvm.org/D84538
This patch addresses two issues:
* Forces the availability of the base-pointer (x19) when the frame has
both scalable vectors and variable-length arrays. Otherwise it will
be expensive to access non-SVE locals.
* In presence of SVE stack objects, it will allocate the emergency
scavenging slot close to the SP, so that they can be accessed from
the SP or BP if available. If accessed from the frame-pointer, it will
otherwise need an extra register to access the scavenging slot because
of mixed scalable/non-scalable addressing modes.
Reviewers: efriedma, ostannard, cameron.mcinally, rengolin, david-arm
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D70174
The code already supports addressing a fixed-size stack object from
the frame-pointer, by first subtracting sizeof(SVE area) from FP.
Reviewers: efriedma, cameron.mcinally, david-arm, rengolin
Reviewed By: david-arm
Differential Revision: https://reviews.llvm.org/D83125
This patch adds a target interface to set the StackID for a given type,
which allows scalable vectors (e.g. `<vscale x 16 x i8>`) to be assigned a
'sve-vec' StackID, so it is allocated in the SVE area of the stack frame.
Reviewers: ostannard, efriedma, rengolin, cameron.mcinally
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D70080
Materialize accesses to SVE frame objects from SP or FP, whichever is
available and beneficial.
This patch still assumes the objects are pre-allocated. The automatic
layout of SVE objects within the stackframe will be added in a separate
patch.
Reviewers: greened, cameron.mcinally, efriedma, rengolin, thegameg, rovka
Reviewed By: cameron.mcinally
Differential Revision: https://reviews.llvm.org/D67749
llvm-svn: 374772
Adds support to AArch64FrameLowering to allocate fixed-stack SVE objects.
The focus of this patch is purely to allow the stack frame to
allocate/deallocate space for scalable SVE objects. More dynamic
allocation (at compile-time, i.e. determining placement of SVE objects
on the stack), or resolving frame-index references that include
scalable-sized offsets, are left for subsequent patches.
SVE objects are allocated in the stack frame as a separate region below
the callee-save area, and above the alignment gap. This is done so that
the SVE objects can be accessed directly from the FP at (runtime)
VL-based offsets to benefit from using the VL-scaled addressing modes.
The layout looks as follows:
+-------------+
| stack arg |
+-------------+
| Callee Saves|
| X29, X30 | (if available)
|-------------| <- FP (if available)
| : |
| SVE area |
| : |
+-------------+
|/////////////| alignment gap.
| : |
| Stack objs |
| : |
+-------------+ <- SP after call and frame-setup
SVE and non-SVE stack objects are distinguished using different
StackIDs. The offsets for objects with TargetStackID::SVEVector should be
interpreted as purely scalable offsets within their respective SVE region.
Reviewers: thegameg, rovka, t.p.northover, efriedma, rengolin, greened
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D61437
llvm-svn: 373585
Sander de Smalen