Fix Bigint_rsh on mips (was obviously not properly tested).

runtime/vm/intrinsifier_mips.cc

 // 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_MIPS.
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 850 matching lines @@
   // T6 = &r_digits[x_used - n ~/ _DIGIT_BITS - 1]
   __ sll(T2, T2, 1);
   __ addu(T6, V1, T2);
   __ subu(T6, T6, T1);
   __ addiu(T6, T6, Immediate(-4));
   // T3 = n % _DIGIT_BITS
   __ andi(T3, T5, Immediate(31));
   // T2 = 32 - T3
   __ subu(T2, ZR, T3);
   __ addiu(T2, T2, Immediate(32));
+  // T1 = x_digits[n ~/ _DIGIT_BITS] >> (n % _DIGIT_BITS)
+  __ lw(T1, Address(V0, 0));
+  __ addiu(V0, V0, Immediate(Bigint::kBytesPerDigit));
   Label loop_exit;
   __ beq(V1, T6, &loop_exit);
-  __ delay_slot()->mov(T1, ZR);
+  __ delay_slot()->srlv(T1, T1, T3);
   Label loop;
   __ Bind(&loop);
   __ lw(T0, Address(V0, 0));
   __ addiu(V0, V0, Immediate(Bigint::kBytesPerDigit));
   __ sllv(AT, T0, T2);
   __ or_(T1, T1, AT);
   __ sw(T1, Address(V1, 0));
   __ addiu(V1, V1, Immediate(Bigint::kBytesPerDigit));
   __ bne(V1, T6, &loop);
   __ delay_slot()->srlv(T1, T0, T3);
@@ skipping 1248 matching lines @@
   Isolate* isolate = Isolate::Current();
   __ LoadImmediate(V0, reinterpret_cast<uword>(isolate));
   // Set return value.
   __ Ret();
   __ delay_slot()->lw(V0, Address(V0, Isolate::current_tag_offset()));
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS