ia32: Remove redundant CTX preservation from intrinsics; tweak definition of CTX.

runtime/vm/constants_ia32.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_CONSTANTS_IA32_H_
 #define VM_CONSTANTS_IA32_H_
 
 #include "platform/assert.h"
 
 namespace dart {
@@ skipping 44 matching lines @@
 // Architecture independent aliases.
 typedef XmmRegister FpuRegister;
 const FpuRegister FpuTMP = XMM0;
 const int kNumberOfFpuRegisters = kNumberOfXmmRegisters;
 const FpuRegister kNoFpuRegister = kNoXmmRegister;
 
 
 // Register aliases.
 const Register TMP = kNoRegister;  // No scratch register used by assembler.
 const Register TMP2 = kNoRegister;  // No second assembler scratch register.
-const Register CTX = ESI;  // Caches current context in generated code.
+const Register CTX = EDI;  // Location of current context at method entry.
 const Register PP = kNoRegister;  // No object pool pointer.
 const Register SPREG = ESP;  // Stack pointer register.
 const Register FPREG = EBP;  // Frame pointer register.
 const Register ICREG = ECX;  // IC data register.
 const Register ARGS_DESC_REG = EDX;  // Arguments descriptor register.
 
 // Exception object is passed in this register to the catch handlers when an
 // exception is thrown.
 const Register kExceptionObjectReg = EAX;
 
@@ skipping 64 matching lines @@
 };
 
 
 // The largest multibyte nop we will emit.  This could go up to 15 if it
 // becomes important to us.
 const int MAX_NOP_SIZE = 8;
 
 }  // namespace dart
 
 #endif  // VM_CONSTANTS_IA32_H_