With the new SVE stack layout, we now need to provide a Darwin variant
for all the calling conventions based on the main AAPCS CSR save order.
This also changes APCS_SwiftError to have a Darwin and a non-Darwin
version, assuming it could be used on other platforms these days, and
restricts the AArch64_CXX_TLS calling convention to Darwin.
Differential Revision: https://reviews.llvm.org/D73805
Changes:
There was a condition for `!NeedsFrameRecord` missing in the assert. The
assert in question has changed to:
+ assert((!RPI.isPaired() || !NeedsFrameRecord || RPI.Reg2 != AArch64::FP ||
+ RPI.Reg1 == AArch64::LR) &&
+ "FrameRecord must be allocated together with LR");
This addresses PR43016.
llvm-svn: 369122
This patch changes the location of the frame-record (FP, LR) to the
bottom of the callee-saved area. According to the AAPCS the location of
the frame-record within the stackframe is unspecified (section 5.2.3 The
Frame Pointer), so the compiler should be free to choose a different
location.
The reason for changing the location of the frame-record is to prepare
the frame for allocating an SVE area below the callee-saves. This way the
compiler can use the VL-scaled addressing modes to directly access SVE
objects from the frame-pointer.
: :
| stack | | stack |
| args | | args |
+-------+ +-------+
| x30 | | x19 |
| x29 | | x20 |
FP -> |- - - -| | x21 |
| x19 | ==> | x22 |
| x20 | |- - - -|
| x21 | | x30 |
| x22 | | x29 |
+-------+ +-------+ <- FP
|///////| |///////| // realignment gap
|- - - -| |- - - -|
|spills/| |spills/|
| locals| | locals|
SP -> +-------+ +-------+ <- SP
Things to point out:
- The algorithm to find a paired register should be prevented from
accidentally pairing some callee-saved register with LR that is not
FP, since they should always be paired together when the frame
has a frame-record.
- For Darwin platforms the location of the frame-record is unchanged,
since the unwind encoding does not allow for encoding this position
dynamically and other tools currently depend on the former layout.
Reviewers: efriedma, rovka, rengolin, thegameg, greened, t.p.northover
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D65653
llvm-svn: 368987
All that you can legitimately do with the CFI for a nounwind function
is get a backtrace, and adjusting the SCS register is not (currently)
required for this purpose.
Differential Revision: https://reviews.llvm.org/D54988
llvm-svn: 348035
When unwinding past a function that uses shadow call stack, we must
subtract 8 from the value of the x18 register. This patch causes us
to emit a call frame instruction that causes that to happen.
Differential Revision: https://reviews.llvm.org/D54609
llvm-svn: 347089
The implementation of shadow call stack on aarch64 is quite different to
the implementation on x86_64. Instead of reserving a segment register for
the shadow call stack, we reserve the platform register, x18. Any function
that spills lr to sp also spills it to the shadow call stack, a pointer to
which is stored in x18.
Differential Revision: https://reviews.llvm.org/D45239
llvm-svn: 329236
Francis Visoiu Mistrih