s390: Fixed error in calculating the power of 2 in Int64Mul

src/compiler/s390/instruction-selector-s390.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 #include "src/s390/frames-s390.h"
 
@@ skipping 1086 matching lines @@
 }
 
 #if V8_TARGET_ARCH_S390X
 void InstructionSelector::VisitInt64Mul(Node* node) {
   S390OperandGenerator g(this);
   Int64BinopMatcher m(node);
   Node* left = m.left().node();
   Node* right = m.right().node();
   if (g.CanBeImmediate(right, kInt32Imm) &&
       base::bits::IsPowerOfTwo64(g.GetImmediate(right))) {
-    int power = 31 - base::bits::CountLeadingZeros64(g.GetImmediate(right));
+    int power = 63 - base::bits::CountLeadingZeros64(g.GetImmediate(right));
     Emit(kS390_ShiftLeft64, g.DefineSameAsFirst(node), g.UseRegister(left),
          g.UseImmediate(power));
     return;
   }
   VisitMul(this, node, kS390_Mul64);
 }
 #endif
 
 void InstructionSelector::VisitInt32MulHigh(Node* node) {
   S390OperandGenerator g(this);
@@ skipping 913 matching lines @@
 // static
 MachineOperatorBuilder::AlignmentRequirements
 InstructionSelector::AlignmentRequirements() {
   return MachineOperatorBuilder::AlignmentRequirements::
       FullUnalignedAccessSupport();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8