MIPS: Fix wrong asserts in SeqStringSetCharGenerator.

src/mips/codegen-mips.cc

 // Copyright 2012 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 515 matching lines @@
                                          Register string,
                                          Register index,
                                          Register value) {
   if (FLAG_debug_code) {
     __ And(at, index, Operand(kSmiTagMask));
     __ Check(eq, "Non-smi index", at, Operand(zero_reg));
     __ And(at, value, Operand(kSmiTagMask));
     __ Check(eq, "Non-smi value", at, Operand(zero_reg));
 
     __ lw(at, FieldMemOperand(string, String::kLengthOffset));
-    __ Check(lt, "Index is too large", at, Operand(index));
+    __ Check(lt, "Index is too large", index, Operand(at));
 
-    __ Check(ge, "Index is negative", index, Operand(Smi::FromInt(0)));
+    __ Check(ge, "Index is negative", index, Operand(zero_reg));
 
     __ lw(at, FieldMemOperand(string, HeapObject::kMapOffset));
     __ lbu(at, FieldMemOperand(at, Map::kInstanceTypeOffset));
 
     __ And(at, at, Operand(kStringRepresentationMask | kStringEncodingMask));
     static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
     static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
-    __ Check(eq, "Unexpected string type", at,
-        Operand(encoding == String::ONE_BYTE_ENCODING
-                    ? one_byte_seq_type : two_byte_seq_type));
+    __ Subu(at, at, Operand(encoding == String::ONE_BYTE_ENCODING
+        ? one_byte_seq_type : two_byte_seq_type));
+    __ Check(eq, "Unexpected string type", at, Operand(zero_reg));
   }
 
   __ Addu(at,
           string,
           Operand(SeqString::kHeaderSize - kHeapObjectTag));
   __ SmiUntag(value);
   STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
   if (encoding == String::ONE_BYTE_ENCODING) {
     __ SmiUntag(index);
     __ Addu(at, at, index);
@@ skipping 149 matching lines @@
     patcher.masm()->dd(reinterpret_cast<uint32_t>(stub->instruction_start()));
   }
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS