[llvm] [BOLT][AArch64] Support for pointer authentication (v2) (PR #120064)

[Paschalis Mpeis via llvm-commits]

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@@ -1599,6 +1599,52 @@ class BinaryFunction {
 
   void setHasInferredProfile(bool Inferred) { HasInferredProfile = Inferred; }
 
+  /// Find corrected offset the same way addCFIInstruction does it to skip NOPs.
+  std::optional<uint64_t> getCorrectedCFIOffset(uint64_t Offset) {
+    assert(!Instructions.empty());
+    auto I = Instructions.lower_bound(Offset);
+    if (Offset == getSize()) {
+      assert(I == Instructions.end() && "unexpected iterator value");
+      // Sometimes compiler issues restore_state after all instructions
+      // in the function (even after nop).
+      --I;
+      Offset = I->first;
+    }
+    assert(I->first == Offset && "CFI pointing to unknown instruction");
+    if (I == Instructions.begin()) {
+      return {};
+    }
+
+    --I;
+    while (I != Instructions.begin() && BC.MIB->isNoop(I->second)) {
+      Offset = I->first;
+      --I;
+    }
+    return Offset;
+  }
+
+  void setInstModifiesRAState(uint8_t CFIOpcode, uint64_t Offset) {
+    std::optional<uint64_t> CorrectedOffset = getCorrectedCFIOffset(Offset);
+    if (CorrectedOffset) {
+      auto I = Instructions.lower_bound(*CorrectedOffset);
+      I--;
+
+      switch (CFIOpcode) {
+      case dwarf::DW_CFA_GNU_window_save:
----------------
paschalis-mpeis wrote:

IMHO, the below looks more natural here:

```suggestion
      case dwarf::DW_CFA_AARCH64_negate_ra_state:
```

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