[llvm] [BOLT][AArch64] Handle OpNegateRAState to enable optimizing binaries with pac-ret hardening (PR #120064)

[Paschalis Mpeis via llvm-commits]

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@@ -0,0 +1,57 @@
+# Checking that we generate an OpNegateRAState CFI after the split point,
+# when splitting a region with signed RA state.
+
+# REQUIRES: system-linux
+
+# RUN: %clang %cflags -o %t %s
+# RUN: %clang %s %cflags -Wl,-q -o %t
+# RUN: link_fdata --no-lbr %s %t %t.fdata
+# RUN: llvm-bolt %t -o %t.bolt --data %t.fdata -split-functions \
+# RUN: --print-only foo --print-split --print-all 2>&1 | FileCheck %s
+
+# Checking that we don't see any OpNegateRAState CFIs before the insertion pass.
+# CHECK-NOT: OpNegateRAState
+# CHECK: Binary Function "foo" after insert-negate-ra-state-pass
+
+# CHECK:       paciasp
+# CHECK-NEXT:  OpNegateRAState
+
+# CHECK: -------   HOT-COLD SPLIT POINT   -------
+
+# CHECK:         OpNegateRAState
+# CHECK-NEXT:    autiasp
+# CHECK-NEXT:    OpNegateRAState
+# CHECK-NEXT:    ret
+
+# CHECK:         autiasp
+# CHECK-NEXT:    OpNegateRAState
+# CHECK-NEXT:    ret
+
+# End of the insert-negate-ra-state-pass logs
+# CHECK: Binary Function "foo" after finalize-functions
+
+  .text
+  .globl  foo
+  .type foo, %function
+foo:
+.cfi_startproc
+.entry_bb:
+# FDATA: 1 foo #.entry_bb# 10
+     paciasp
+    .cfi_negate_ra_state     // indicating that paciasp changed the RA state to signed
+    cmp x0, #0
+    b.eq .Lcold_bb1
+.Lfallthrough:
+    autiasp
+    .cfi_negate_ra_state     // indicating that autiasp changed the RA state to unsigned
+    ret
+    .cfi_negate_ra_state     // ret has unsigned RA state, but the next inst (autiasp) has signed RA state
+.Lcold_bb1:                  // split point
----------------
paschalis-mpeis wrote:

Could you move the label earlier as below to align with what we expect?

```suggestion
.Lcold_bb1:                  // split point
    .cfi_negate_ra_state     // ret has unsigned RA state, but the next inst (autiasp) has signed RA state
```

https://github.com/llvm/llvm-project/pull/120064