[llvm] [SandboxIR][NFC] Introduce templated CastInstImpl to simplify subclasses (PR #101427)

[Arthur Eubanks via llvm-commits]

================
@@ -1431,146 +1431,42 @@ class CastInst : public Instruction {
 #endif
 };
 
-class SIToFPInst final : public CastInst {
+// Helper class to simplify stamping out CastInst subclasses.
+template <Instruction::Opcode Op> class CastInstImpl : public CastInst {
 public:
   static Value *create(Value *Src, Type *DestTy, BBIterator WhereIt,
                        BasicBlock *WhereBB, Context &Ctx,
-                       const Twine &Name = "");
-  static Value *create(Value *Src, Type *DestTy, Instruction *InsertBefore,
-                       Context &Ctx, const Twine &Name = "");
-  static Value *create(Value *Src, Type *DestTy, BasicBlock *InsertAtEnd,
-                       Context &Ctx, const Twine &Name = "");
-
-  static bool classof(const Value *From) {
-    if (auto *I = dyn_cast<Instruction>(From))
-      return I->getOpcode() == Opcode::SIToFP;
-    return false;
+                       const Twine &Name = "") {
+    return CastInst::create(DestTy, Op, Src, WhereIt, WhereBB, Ctx, Name);
   }
-#ifndef NDEBUG
-  void dump(raw_ostream &OS) const final;
-  LLVM_DUMP_METHOD void dump() const final;
-#endif // NDEBUG
-};
-
-class FPToUIInst final : public CastInst {
-public:
-  static Value *create(Value *Src, Type *DestTy, BBIterator WhereIt,
-                       BasicBlock *WhereBB, Context &Ctx,
-                       const Twine &Name = "");
   static Value *create(Value *Src, Type *DestTy, Instruction *InsertBefore,
-                       Context &Ctx, const Twine &Name = "");
-  static Value *create(Value *Src, Type *DestTy, BasicBlock *InsertAtEnd,
-                       Context &Ctx, const Twine &Name = "");
-
-  static bool classof(const Value *From) {
-    if (auto *I = dyn_cast<Instruction>(From))
-      return I->getOpcode() == Opcode::FPToUI;
-    return false;
+                       Context &Ctx, const Twine &Name = "") {
+    return create(Src, DestTy, InsertBefore->getIterator(),
+                  InsertBefore->getParent(), Ctx, Name);
   }
-#ifndef NDEBUG
----------------
aeubanks wrote:

it looks like all `dump()` methods are the same right now, with multi-instructions being different in the future. there's gotta be a better way of deduplicating some of the logic, seeing so many copies of

```
void FooInst::dump(raw_ostream &OS) const {
  dumpCommonPrefix(OS);
  dumpCommonSuffix(OS);
}
```

hurts.

can you test if `B().f()` in
```
struct A {
    void f();
};

struct B : A {
    using A::f;
};
```
works with gdb?

https://github.com/llvm/llvm-project/pull/101427