Daniil Kovalev da083e358e [PAC][CodeGen][ELF][AArch64] Support signed GOT (#113811) ...

This re-applies #96164 after revert in #102434.

Support the following relocations and assembly operators:

- `R_AARCH64_AUTH_ADR_GOT_PAGE` (`:got_auth:` for `adrp`)
- `R_AARCH64_AUTH_LD64_GOT_LO12_NC` (`:got_auth_lo12:` for `ldr`)
- `R_AARCH64_AUTH_GOT_ADD_LO12_NC` (`:got_auth_lo12:` for `add`)

`LOADgotAUTH` pseudo-instruction is introduced which is later expanded to
actual instruction sequence like the following.

```
adrp x16, :got_auth:sym
add x16, x16, :got_auth_lo12:sym
ldr x0, [x16]
autia x0, x16
```

If a resign is requested, like below, `LOADgotPAC` pseudo is used, and GOT
load is lowered similarly to `LOADgotAUTH`.

```
@var = global i32 0
define ptr @resign_globalvar() {
  ret ptr ptrauth (ptr @var, i32 3, i64 43)
}
```

If FPAC bit is not set and auth instruction is emitted, a check+trap sequence
similar to one used for `AUT` pseudo is emitted to ensure auth success.

Both SelectionDAG and GlobalISel are suppported.
For FastISel, we fall back to SelectionDAG.

Tests starting with 'ptrauth-' have corresponding variants w/o this prefix.

See also specification
https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#appendix-signed-got

2024-11-01 12:21:10 +03:00

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