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llvm-mirror/test/CodeGen/AArch64/swift-async-unwind.ll
Tim Northover 5661b7eb80 IR+AArch64: add a "swiftasync" argument attribute.
This extends any frame record created in the function to include that
parameter, passed in X22.

The new record looks like [X22, FP, LR] in memory, and FP is stored with 0b0001
in bits 63:60 (CodeGen assumes they are 0b0000 in normal operation). The effect
of this is that tools walking the stack should expect to see one of three
values there:

  * 0b0000 => a normal, non-extended record with just [FP, LR]
  * 0b0001 => the extended record [X22, FP, LR]
  * 0b1111 => kernel space, and a non-extended record.

All other values are currently reserved.

If compiling for arm64e this context pointer is address-discriminated with the
discriminator 0xc31a and the DB (process-specific) key.

There is also an "i8** @llvm.swift.async.context.addr()" intrinsic providing
front-ends access to this slot (and forcing its creation initialized to nullptr
if necessary).
2021-05-14 11:43:58 +01:00

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LLVM

; RUN: llc -mtriple=arm64-apple-ios %s -filetype=obj -o - | llvm-objdump --unwind-info - | FileCheck %s
; Swift asynchronous context is incompatible with the compact unwind encoding
; that currently exists and assumes callee-saved registers are right next to FP
; in a particular order. This isn't a problem now because C++ exceptions aren't
; allowed to unwind through Swift code, but at least make sure the compact info
; says to use DWARF correctly.
; CHECK: compact encoding: 0x03000000
define void @foo(i8* swiftasync %in) "frame-pointer"="all" {
call void asm sideeffect "", "~{x23}"()
ret void
}