[BOLT] Extend Inliner to work on functions with Pointer Autentication

bolt/include/bolt/Core/MCPlusBuilder.h

@@ -632,6 +632,12 @@ class MCPlusBuilder {
     return false;
   }
 
+  /// Generate the matching pointer authentication instruction from a fused
+  /// pauth-and-return instruction.
+  virtual void createMatchingAuth(const MCInst &AuthAndRet, MCInst &Auth) {
+    llvm_unreachable("not implemented");
+  }
+
   /// Returns the register used as a return address. Returns std::nullopt if
   /// not applicable, such as reading the return address from a system register
   /// or from the stack.

bolt/lib/Passes/Inliner.cpp

@@ -195,6 +195,13 @@ InliningInfo getInliningInfo(const BinaryFunction &BF) {
         if (BC.MIB->isPush(Inst) || BC.MIB->isPop(Inst))
           continue;
 
+        // Pointer signing and authenticatin instructions are used around
+        // Push and Pop. These are also straightforward to handle.
+        if (BC.isAArch64() &&
+            (BC.MIB->isPSignOnLR(Inst) || BC.MIB->isPAuthOnLR(Inst) ||
+             BC.MIB->isPAuthAndRet(Inst)))
+          continue;
+
         DirectSP |= BC.MIB->hasDefOfPhysReg(Inst, SPReg) ||
                     BC.MIB->hasUseOfPhysReg(Inst, SPReg);
       }
@@ -338,6 +345,17 @@ Inliner::inlineCall(BinaryBasicBlock &CallerBB,
                                 BC.Ctx.get());
       }
 
+      // Handling fused authentication and return instructions (Armv8.3-A):
+      // if the Return here is RETA(A|B), we have to keep the authentication
+      // part.
+      // RETAA -> AUTIASP + RET
+      // RETAB -> AUTIBSP + RET
+      if (BC.isAArch64() && BC.MIB->isPAuthAndRet(Inst)) {
+        MCInst Auth;
+        BC.MIB->createMatchingAuth(Inst, Auth);
+        InsertII =
+            std::next(InlinedBB->insertInstruction(InsertII, std::move(Auth)));
+      }
       if (CSIsTailCall || (!MIB.isCall(Inst) && !MIB.isReturn(Inst))) {
         InsertII =
             std::next(InlinedBB->insertInstruction(InsertII, std::move(Inst)));

bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp

@@ -266,6 +266,35 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
            Inst.getOpcode() == AArch64::RETABSPPCr;
   }
 
+  void createMatchingAuth(const MCInst &AuthAndRet, MCInst &Auth) override {
+    assert(isPAuthAndRet(AuthAndRet) &&
+           "Not a fused pauth-and-return instruction");
+
+    Auth.clear();
+    switch (AuthAndRet.getOpcode()) {
+    case AArch64::RETAA:
+      Auth.setOpcode(AArch64::AUTIASP);
+      break;
+    case AArch64::RETAB:
+      Auth.setOpcode(AArch64::AUTIBSP);
+      break;
+    case AArch64::RETAASPPCi:
+      Auth.setOpcode(AArch64::AUTIASPPCi);
+      break;
+    case AArch64::RETABSPPCi:
+      Auth.setOpcode(AArch64::AUTIBSPPCi);
+      break;
+    case AArch64::RETAASPPCr:
+      Auth.setOpcode(AArch64::AUTIASPPCr);
+      break;
+    case AArch64::RETABSPPCr:
+      Auth.setOpcode(AArch64::AUTIBSPPCr);
+      break;
+    default:
+      llvm_unreachable("Unhandled fused pauth-and-return instruction");
+    }
+  }
+
   std::optional<MCPhysReg> getSignedReg(const MCInst &Inst) const override {
     switch (Inst.getOpcode()) {
     case AArch64::PACIA:

bolt/test/AArch64/inline-armv8.3-returns.s

@@ -0,0 +1,45 @@
+# This test checks that inlining functions with fused pointer-auth-and-return
+# instructions is properly handled by BOLT.
+
+# REQUIRES: system-linux
+
+# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown -mattr=+v8.3a %s -o %t.o
+# RUN: %clang %cflags -O0 %t.o -o %t.exe -Wl,-q
+# RUN: llvm-bolt --inline-all --print-inline  --print-only=_Z3barP1A  \
+# RUN: %t.exe -o %t.bolt  | FileCheck %s
+
+# CHECK: BOLT-INFO: inlined 0 calls at 1 call sites in 2 iteration(s). Change in binary size: 8 bytes.
+# CHECK: Binary Function "_Z3barP1A" after inlining {
+# CHECK-NOT: bl	_Z3fooP1A
+# CHECK: ldr	x8, [x0]
+# CHECK-NEXT: ldr	w0, [x8]
+# CHECK-NEXT: autiasp
+
+	.text
+	.globl	_Z3fooP1A
+	.type	_Z3fooP1A,@function
+_Z3fooP1A:
+    paciasp
+	ldr	x8, [x0]
+	ldr	w0, [x8]
+	retaa
+	.size	_Z3fooP1A, .-_Z3fooP1A
+
+	.globl	_Z3barP1A
+	.type	_Z3barP1A,@function
+_Z3barP1A:
+	stp	x29, x30, [sp, #-16]!
+	mov	x29, sp
+	bl	_Z3fooP1A
+	mul	w0, w0, w0
+	ldp	x29, x30, [sp], #16
+	ret
+	.size	_Z3barP1A, .-_Z3barP1A
+
+	.globl	main
+	.p2align	2
+	.type	main,@function
+main:
+	mov	w0, wzr
+	ret
+	.size	main, .-main