Added bswap r16 instruction, which has undefined behavior, but is encodable

src/asmjit/core/emitter.h

@@ -67,11 +67,16 @@ public:
 
   //! Emitter type.
   enum EmitterType : uint32_t {
-    kTypeNone      = 0,
+    //! Unknown or uninitialized.
+    kTypeNone = 0,
+    //! Emitter inherits from `BaseAssembler`.
     kTypeAssembler = 1,
-    kTypeBuilder   = 2,
-    kTypeCompiler  = 3,
-    kTypeCount     = 4
+    //! Emitter inherits from `BaseBuilder`.
+    kTypeBuilder = 2,
+    //! Emitter inherits from `BaseCompiler`.
+    kTypeCompiler = 3,
+    //! Count of emitter types.
+    kTypeCount = 4
   };
 
   //! Emitter flags.

src/asmjit/x86/x86assembler.cpp

@@ -1015,11 +1015,11 @@ CaseX86M_GPB_MulDiv:
 
     case InstDB::kEncodingX86Bswap:
       if (isign3 == ENC_OPS1(Reg)) {
-        if (ASMJIT_UNLIKELY(o0.size() < 4))
+        if (ASMJIT_UNLIKELY(o0.size() == 1))
           goto InvalidInstruction;
 
         opReg = o0.id();
-        opcode.addWBySize(o0.size());
+        opcode.addPrefixBySize(o0.size());
         goto EmitX86OpReg;
       }
       break;