VM: Improve receiver class check in polymorphic inlining.

runtime/vm/disassembler_ia32.cc

Index: runtime/vm/disassembler_ia32.cc
===================================================================
--- runtime/vm/disassembler_ia32.cc	(revision 38058)
+++ runtime/vm/disassembler_ia32.cc	(working copy)
@@ -239,6 +239,7 @@
     case 0xAF: return "imul";
     case 0xA5: return "shld";
     case 0xAD: return "shrd";
+    case 0xA3: return "bt";
     case 0xAB: return "bts";
     case 0xBD: return "bsr";
     case 0xB1: return "cmpxchg";
@@ -1409,14 +1410,17 @@
           }
         } else {
           data += 2;
-          if (f0byte == 0xAB || f0byte == 0xA5 || f0byte == 0xAD) {
-            // shrd, shld, bts
+          if (f0byte == 0xAB ||
+              f0byte == 0xA5 ||
+              f0byte == 0xAD ||
+              f0byte == 0xA3) {
+            // shrd, shld, bts, bt
             Print(f0mnem);
             int mod, regop, rm;
             GetModRm(*data, &mod, &regop, &rm);
             Print(" ");
             data += PrintRightOperand(data);
-            if (f0byte == 0xAB) {
+            if (f0byte == 0xAB || f0byte == 0xA3) {
               Print(",");
               PrintCPURegister(regop);
             } else {
@@ -1814,7 +1818,7 @@
   ASSERT(instr_len > 0);  // Ensure progress.
 
   return instr_len;
-}
+}  // NOLINT

[Cutch, 2014/07/09 19:22:53]

Did you add this to avoid the function length lint warning? I wonder if it would
be better to start refactoring the function to shorten its length.

[Florian Schneider, 2014/07/10 09:00:59]

Yes, I don't know if the lint warning makes sense here: The reason for this
large function is the huge switch statement, and splitting it does not make it
more readable in my opinion. It does the opposite: Making the reader jump back
and forth between helper functions that are used in exactly one place.

 
 
 void Disassembler::DecodeInstruction(char* hex_buffer, intptr_t hex_size,