Implement Smi_bitLength intrinsic on mips, arm, and arm64.

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 770 matching lines @@
 
 void Intrinsifier::Smi_bitNegate(Assembler* assembler) {
   __ lw(T0, Address(SP, 0 * kWordSize));
   __ nor(V0, T0, ZR);
   __ Ret();
   __ delay_slot()->addiu(V0, V0, Immediate(-1));  // Remove inverted smi-tag.
 }
 
 
 void Intrinsifier::Smi_bitLength(Assembler* assembler) {
-  // TODO(sra): Implement.
+  __ lw(V0, Address(SP, 0 * kWordSize));
+  __ SmiUntag(V0);
+  // XOR with sign bit to complement bits if value is negative.
+  __ sra(T0, V0, 31);
+  __ xor_(V0, V0, T0);
+  __ clz(V0, V0);
+  __ LoadImmediate(T0, 32);
+  __ subu(V0, T0, V0);
+  __ Ret();
+  __ delay_slot()->SmiTag(V0);
 }
 
 
 void Intrinsifier::Bigint_lsh(Assembler* assembler) {
   // static void _lsh(Uint32List x_digits, int x_used, int n,
   //                  Uint32List r_digits)
 
   // T2 = x_used, T3 = x_digits, x_used > 0, x_used is Smi.
   __ lw(T2, Address(SP, 2 * kWordSize));
   __ lw(T3, Address(SP, 3 * kWordSize));
@@ skipping 1333 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