Allow esi to be an allocatable register on IA32.

src/ia32/macro-assembler-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 60 matching lines @@
 
   // Set dirty mark for region.
   bts(Operand(object, Page::kDirtyFlagOffset), addr);
 }
 
 
 void MacroAssembler::RecordWrite(Register object,
                                  int offset,
                                  Register value,
                                  Register scratch) {
-  // The compiled code assumes that record write doesn't change the
-  // context register, so we check that none of the clobbered
-  // registers are esi.
-  ASSERT(!object.is(esi) && !value.is(esi) && !scratch.is(esi));
-
   // First, check if a write barrier is even needed. The tests below
   // catch stores of Smis and stores into young gen.
   NearLabel done;
 
   // Skip barrier if writing a smi.
   ASSERT_EQ(0, kSmiTag);
   test(value, Immediate(kSmiTagMask));
   j(zero, &done);
 
   InNewSpace(object, value, equal, &done);
@@ skipping 26 matching lines @@
     mov(object, Immediate(BitCast<int32_t>(kZapValue)));
     mov(value, Immediate(BitCast<int32_t>(kZapValue)));
     mov(scratch, Immediate(BitCast<int32_t>(kZapValue)));
   }
 }
 
 
 void MacroAssembler::RecordWrite(Register object,
                                  Register address,
                                  Register value) {
-  // The compiled code assumes that record write doesn't change the
-  // context register, so we check that none of the clobbered
-  // registers are esi.
-  ASSERT(!object.is(esi) && !value.is(esi) && !address.is(esi));
-
   // First, check if a write barrier is even needed. The tests below
   // catch stores of Smis and stores into young gen.
   Label done;
 
   // Skip barrier if writing a smi.
   ASSERT_EQ(0, kSmiTag);
   test(value, Immediate(kSmiTagMask));
   j(zero, &done);
 
   InNewSpace(object, value, equal, &done);
@@ skipping 1752 matching lines @@
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32