ARM: Check that address given to __ RecordWrite is correct.

src/arm/macro-assembler-arm.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
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@@ skipping 465 matching lines @@
                                  Register value,
                                  LinkRegisterStatus lr_status,
                                  SaveFPRegsMode fp_mode,
                                  RememberedSetAction remembered_set_action,
                                  SmiCheck smi_check) {
   // The compiled code assumes that record write doesn't change the
   // context register, so we check that none of the clobbered
   // registers are cp.
   ASSERT(!address.is(cp) && !value.is(cp));
 
+  if (FLAG_debug_code) {

[Kevin Millikin (Chromium), 2011/11/11 11:28:37]

We don't use FLAG_debug_code in the macro assembler.  Use emit_debug_code so
that we can override the flag if we need to.

+    Label ok;
+    ldr(ip, MemOperand(address));
+    cmp(ip, value);
+    b(eq, &ok);

[Kevin Millikin (Chromium), 2011/11/11 11:32:23]

Also, while I think of it, is there a reason not to use

Check(eq, "Wrong address or value passed to RecordWrite")

?

+    stop("Wrong address or value passed to RecordWrite");
+    bind(&ok);
+  }
+
   Label done;
 
   if (smi_check == INLINE_SMI_CHECK) {
     ASSERT_EQ(0, kSmiTag);
     tst(value, Operand(kSmiTagMask));
     b(eq, &done);
   }
 
   CheckPageFlag(value,
                 value,  // Used as scratch.
@@ skipping 3097 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM