ir/value: Add member function to check whether or not all bits of a contained value are set

This is useful when we wish to know if a contained value is something
like 0xFFFFFFFF, as this helps perform constant folding. For example the
operation: x & 0xFFFFFFFF can be folded to just x in the 32-bit case.

src/frontend/ir/value.cpp

@@ -174,4 +174,24 @@ u64 Value::GetImmediateAsU64() const {
     }
 }
 
+bool Value::HasAllBitsSet() const {
+    ASSERT(IsImmediate());
+
+    switch (GetType()) {
+    case IR::Type::U1:
+        return GetU1();
+    case IR::Type::U8:
+        return GetU8() == 0xFF;
+    case IR::Type::U16:
+        return GetU16() == 0xFFFF;
+    case IR::Type::U32:
+        return GetU32() == 0xFFFFFFFF;
+    case IR::Type::U64:
+        return GetU64() == 0xFFFFFFFFFFFFFFFF;
+    default:
+        ASSERT_MSG(false, "HasAllBitsSet called on an incompatible Value type.");
+        return false;
+    }
+}
+
 } // namespace Dynarmic::IR

src/frontend/ir/value.h

@@ -74,6 +74,14 @@ public:
      */
     u64 GetImmediateAsU64() const;
 
+    /**
+     * Determines whether or not the contained constant value has all bits set.
+     *
+     * @pre The value contains either a U1, U8, U16, U32, or U64 value.
+     *      Breaking this precondition will cause an assertion to be invoked.
+     */
+    bool HasAllBitsSet() const;
+
 private:
     Type type;