Teach the assembler how to generate multi-byte nops. Teach the

runtime/vm/disassembler_ia32.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_IA32.
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/disassembler.h"
 
 #include "vm/allocation.h"
@@ skipping 1104 matching lines @@
           data += CMov(data);
         } else if (f0byte == 0x2F) {
           data += 2;
           int mod, regop, rm;
           GetModRm(*data, &mod, &regop, &rm);
           Print("comiss ");
           PrintXmmRegister(regop);
           Print(",");
           PrintXmmRegister(rm);
           data++;
+        } else if (f0byte == 0x1F) {
+          if (*(data+2) == 0x00) {
+            Print("nop");
+            data += 3;
+          } else if (*(data+2) == 0x40 && *(data+3) == 0x00) {
+            Print("nop");
+            data += 4;
+          } else if (*(data+2) == 0x44 &&
+                     *(data+3) == 0x00 &&
+                     *(data+4) == 0x00) {
+            Print("nop");
+            data += 5;
+          } else if (*(data+2) == 0x80 &&
+                     *(data+3) == 0x00 &&
+                     *(data+3) == 0x00 &&
+                     *(data+3) == 0x00 &&
+                     *(data+4) == 0x00) {
+            Print("nop");
+            data += 7;
+          } else if (*(data+2) == 0x84 &&
+                     *(data+3) == 0x00 &&
+                     *(data+3) == 0x00 &&
+                     *(data+3) == 0x00 &&
+                     *(data+3) == 0x00 &&
+                     *(data+4) == 0x00) {
+            Print("nop");
+            data += 8;
+          } else {
+            UNIMPLEMENTED();
+          }
         } else {
           data += 2;
           if (f0byte == 0xAB || f0byte == 0xA5 || f0byte == 0xAD) {
             // shrd, shld, bts
             Print(f0mnem);
             int mod, regop, rm;
             GetModRm(*data, &mod, &regop, &rm);
             data += PrintRightOperand(data);
             if (f0byte == 0xAB) {
               Print(",");
@@ skipping 124 matching lines @@
           } else if (*data == 0x57 || *data == 0x54) {
             const char* mnem = (*data == 0x57) ? "xorpd" : "andpd";
             data++;
             int mod, regop, rm;
             GetModRm(*data, &mod, &regop, &rm);
             Print(mnem);
             Print(" ");
             PrintXmmRegister(regop);
             Print(",");
             data += PrintRightXmmOperand(data);
+          } else if (*data == 0x1F &&
+                     *(data+1) == 0x44 &&
+                     *(data+2) == 0x00 &&
+                     *(data+3) == 0x00) {
+            data += 4;
+            Print("nop");
           } else {
             UNIMPLEMENTED();
           }
+        } else if (*data == 0x90) {
+          data++;
+          Print("nop");
         } else {
           UNIMPLEMENTED();
         }
         break;
 
       case 0xFE:
       { data++;
         int mod, regop, rm;
         GetModRm(*data, &mod, &regop, &rm);
         if (mod == 3 && regop == ecx) {
@@ skipping 255 matching lines @@
                                   human_buffer,
                                   sizeof(human_buffer),
                                   pc);
     pc += instruction_length;
   }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32