[clang][bytecode][NFC] Simplify align_up/down implementation (llvm#160880)

Fix a double assignment to a local variable and use the new popToAPSInt() overload.

Author: tbaederr

clang/lib/AST/ByteCode/InterpBuiltin.cpp

@@ -1169,8 +1169,7 @@ static bool interp__builtin_is_aligned_up_down(InterpState &S, CodePtr OpPC,
  const InterpFrame *Frame,
  const CallExpr *Call,
  unsigned BuiltinOp) {
- PrimType AlignmentT = *S.Ctx.classify(Call->getArg(1));
- const APSInt &Alignment = popToAPSInt(S.Stk, AlignmentT);
+ const APSInt &Alignment = popToAPSInt(S, Call->getArg(1));
 
  if (Alignment < 0 || !Alignment.isPowerOf2()) {
  S.FFDiag(Call, diag::note_constexpr_invalid_alignment) << Alignment;
@@ -1184,8 +1183,7 @@ static bool interp__builtin_is_aligned_up_down(InterpState &S, CodePtr OpPC,
  return false;
  }
 
- // The first parameter is either an integer or a pointer (but not a function
- // pointer).
+ // The first parameter is either an integer or a pointer.
  PrimType FirstArgT = *S.Ctx.classify(Call->getArg(0));
 
  if (isIntegralType(FirstArgT)) {
@@ -1204,12 +1202,12 @@ static bool interp__builtin_is_aligned_up_down(InterpState &S, CodePtr OpPC,
  }
  return true;
  }
-
  assert(FirstArgT == PT_Ptr);
  const Pointer &Ptr = S.Stk.pop<Pointer>();
+ if (!Ptr.isBlockPointer())
+ return false;
 
- unsigned PtrOffset = Ptr.getByteOffset();
- PtrOffset = Ptr.getIndex();
+ unsigned PtrOffset = Ptr.getIndex();
  CharUnits BaseAlignment =
  S.getASTContext().getDeclAlign(Ptr.getDeclDesc()->asValueDecl());
  CharUnits PtrAlign =