[clang] [clang][PAC] Support trivially_relocating polymorphic objects (PR #144420)

[Oliver Hunt via cfe-commits]

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@@ -4467,17 +4467,25 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__builtin_trivially_relocate:
   case Builtin::BImemmove:
   case Builtin::BI__builtin_memmove: {
+    QualType CopiedType = E->getArg(0)->getType()->getPointeeType();
     Address Dest = EmitPointerWithAlignment(E->getArg(0));
     Address Src = EmitPointerWithAlignment(E->getArg(1));
     Value *SizeVal = EmitScalarExpr(E->getArg(2));
-    if (BuiltinIDIfNoAsmLabel == Builtin::BI__builtin_trivially_relocate)
+    if (BuiltinIDIfNoAsmLabel == Builtin::BI__builtin_trivially_relocate) {
+      QualType BaseElementType = getContext().getBaseElementType(CopiedType);
+      if (getContext().containsAddressDiscriminatedPointerAuth(
+              BaseElementType)) {
+        llvm::Instruction *LastFixupInstruction =
+            EmitPointerAuthRelocationFixup(CopiedType, Dest, Src, SizeVal);
+        addInstToNewSourceAtom(LastFixupInstruction, nullptr);
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ojhunt wrote:

I was so confused by this comment, to the extent I thought I had managed to break this and not catch it, but yet I agree now the name should be changed :D

When I first wrote this the memmove was not part of that function, so it was purely a fixup, but that is obviously no longer the case.

https://github.com/llvm/llvm-project/pull/144420