Implement byte swapping instructions on MIPS32 and MIPS64.

src/mips/disasm-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A Disassembler object is used to disassemble a block of code instruction by
 // instruction. The default implementation of the NameConverter object can be
 // overriden to modify register names or to do symbol lookup on addresses.
 //
 // The example below will disassemble a block of code and print it to stdout.
 //
@@ skipping 1246 matching lines @@
       int sa = instr->SaFieldRaw() >> kSaShift;
       switch (sa) {
         case BITSWAP: {
           if (IsMipsArchVariant(kMips32r6)) {
             Format(instr, "bitswap 'rd, 'rt");
           } else {
             Unknown(instr);
           }
           break;
         }
-        case SEB:
-        case SEH:
-        case WSBH:
-          UNREACHABLE();
+        case SEB: {
+          if (IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6)) {
+            Format(instr, "seb     'rd, 'rt");
+          } else {
+            Unknown(instr);
+          }
           break;
+        }
+        case SEH: {
+          if (IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6)) {
+            Format(instr, "seh     'rd, 'rt");
+          } else {
+            Unknown(instr);
+          }
+          break;
+        }
+        case WSBH: {
+          if (IsMipsArchVariant(kMips32r2) || IsMipsArchVariant(kMips32r6)) {
+            Format(instr, "wsbh    'rd, 'rt");
+          } else {
+            Unknown(instr);
+          }
+          break;
+        }
         default: {
           sa >>= kBp2Bits;
           switch (sa) {
             case ALIGN: {
               if (IsMipsArchVariant(kMips32r6)) {
                 Format(instr, "align  'rd, 'rs, 'rt, 'bp2");
               } else {
                 Unknown(instr);
               }
               break;
@@ skipping 484 matching lines @@
                          *reinterpret_cast<int32_t*>(prev_pc), buffer.start());
   }
 }
 
 
 #undef UNSUPPORTED
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_MIPS