MCSpecifierExpr: Make dtor defaulted

Author: MaskRay

llvm/include/llvm/MC/MCExpr.h

@@ -506,6 +506,9 @@ class LLVM_ABI MCTargetExpr : public MCExpr {
 /// Extension point for target-specific MCExpr subclasses with a relocation
 /// specifier, serving as a replacement for MCSymbolRefExpr::VariantKind.
 /// Limit this to top-level use, avoiding its inclusion as a subexpression.
+///
+/// NOTE: All subclasses are required to have trivial destructors because
+/// MCExprs are bump pointer allocated and not destructed.
 class LLVM_ABI MCSpecifierExpr : public MCExpr {
 protected:
   using Spec = uint16_t;
@@ -516,7 +519,7 @@ class LLVM_ABI MCSpecifierExpr : public MCExpr {
 protected:
   explicit MCSpecifierExpr(const MCExpr *Expr, Spec S)
       : MCExpr(Specifier, SMLoc()), Expr(Expr), specifier(S) {}
-  virtual ~MCSpecifierExpr();
+  virtual ~MCSpecifierExpr() = default;
 
 public:
   Spec getSpecifier() const { return specifier; }

llvm/lib/MC/MCExpr.cpp

@@ -767,8 +767,6 @@ MCFragment *MCExpr::findAssociatedFragment() const {
   llvm_unreachable("Invalid assembly expression kind!");
 }
 
-MCSpecifierExpr::~MCSpecifierExpr() {}
-
 bool MCSpecifierExpr::evaluateAsRelocatableImpl(MCValue &Res,
                                                 const MCAssembler *Asm) const {
   if (!getSubExpr()->evaluateAsRelocatable(Res, Asm))