Adds back arm ldrex strex.

runtime/vm/assembler_arm.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"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 551 matching lines @@
   EmitMultiMemOp(cond, am, false, base, regs);
   if (TargetCPUFeatures::arm_version() == ARMv5TE) {
     // On ARMv5, touching a "banked" register after an stm gives undefined
     // behavior, so we just add a nop here to make that case easy to avoid.
     nop();
   }
 }
 
 
 void Assembler::ldrex(Register rt, Register rn, Condition cond) {
+  ASSERT(TargetCPUFeatures::arm_version() != ARMv5TE);
   ASSERT(rn != kNoRegister);
   ASSERT(rt != kNoRegister);
   ASSERT(cond != kNoCondition);
   int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                      B24 |
                      B23 |
                      L   |
                      (static_cast<int32_t>(rn) << kLdExRnShift) |
                      (static_cast<int32_t>(rt) << kLdExRtShift) |
                      B11 | B10 | B9 | B8 | B7 | B4 | B3 | B2 | B1 | B0;
   Emit(encoding);
 }
 
 
 void Assembler::strex(Register rd, Register rt, Register rn, Condition cond) {
+  ASSERT(TargetCPUFeatures::arm_version() != ARMv5TE);
   ASSERT(rn != kNoRegister);
   ASSERT(rd != kNoRegister);
   ASSERT(rt != kNoRegister);
   ASSERT(cond != kNoCondition);
   int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                      B24 |
                      B23 |
                      (static_cast<int32_t>(rn) << kStrExRnShift) |
                      (static_cast<int32_t>(rd) << kStrExRdShift) |
                      B11 | B10 | B9 | B8 | B7 | B4 |
                      (static_cast<int32_t>(rt) << kStrExRtShift);
   Emit(encoding);
 }
 
 
 void Assembler::clrex() {
+  ASSERT(TargetCPUFeatures::arm_version() != ARMv5TE);
   int32_t encoding = (kSpecialCondition << kConditionShift) |
                      B26 | B24 | B22 | B21 | B20 | (0xff << 12) | B4 | 0xf;
   Emit(encoding);
 }
 
 
 void Assembler::nop(Condition cond) {
   ASSERT(cond != kNoCondition);
   int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                      B25 | B24 | B21 | (0xf << 12);
@@ skipping 2783 matching lines @@
 
 
 const char* Assembler::FpuRegisterName(FpuRegister reg) {
   ASSERT((0 <= reg) && (reg < kNumberOfFpuRegisters));
   return fpu_reg_names[reg];
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM