Use Rotate*() functions instead of doing this manually.

src/arm/assembler-arm.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 993 matching lines @@
 // Low-level code emission routines depending on the addressing mode.
 // If this returns true then you have to use the rotate_imm and immed_8
 // that it returns, because it may have already changed the instruction
 // to match them!
 static bool fits_shifter(uint32_t imm32,
                          uint32_t* rotate_imm,
                          uint32_t* immed_8,
                          Instr* instr) {
   // imm32 must be unsigned.
   for (int rot = 0; rot < 16; rot++) {
-    uint32_t imm8 =
-        rot == 0 ? imm32 : (imm32 << 2 * rot) | (imm32 >> (32 - 2 * rot));
+    uint32_t imm8 = base::bits::RotateLeft32(imm32, 2 * rot);
     if ((imm8 <= 0xff)) {
       *rotate_imm = rot;
       *immed_8 = imm8;
       return true;
     }
   }
   // If the opcode is one with a complementary version and the complementary
   // immediate fits, change the opcode.
   if (instr != NULL) {
     if ((*instr & kMovMvnMask) == kMovMvnPattern) {
@@ skipping 2292 matching lines @@
 
 Instr Assembler::PatchMovwImmediate(Instr instruction, uint32_t immediate) {
   instruction &= ~EncodeMovwImmediate(0xffff);
   return instruction | EncodeMovwImmediate(immediate);
 }
 
 
 int Assembler::DecodeShiftImm(Instr instr) {
   int rotate = Instruction::RotateValue(instr) * 2;
   int immed8 = Instruction::Immed8Value(instr);
-  return (immed8 >> rotate) | (immed8 << (32 - rotate));
+  return base::bits::RotateRight32(immed8, rotate);
 }
 
 
 Instr Assembler::PatchShiftImm(Instr instr, int immed) {
   uint32_t rotate_imm = 0;
   uint32_t immed_8 = 0;
   bool immed_fits = fits_shifter(immed, &rotate_imm, &immed_8, NULL);
   DCHECK(immed_fits);
   USE(immed_fits);
   return (instr & ~kOff12Mask) | (rotate_imm << 8) | immed_8;
@@ skipping 669 matching lines @@
       assm->instr_at_put(
           rinfo.pc(), Assembler::SetLdrRegisterImmediateOffset(instr, offset));
     }
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM