[Atomics] Make Atomics.exchange a builtin using TF

src/compiler/arm/code-generator-arm.cc

 // Copyright 2014 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/compiler/code-generator.h"
 
 #include "src/arm/macro-assembler-arm.h"
 #include "src/compilation-info.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
@@ skipping 402 matching lines @@
   } while (0)
 
 #define ASSEMBLE_ATOMIC_STORE_INTEGER(asm_instr)                      \
   do {                                                                \
     __ dmb(ISH);                                                      \
     __ asm_instr(i.InputRegister(2),                                  \
                  MemOperand(i.InputRegister(0), i.InputRegister(1))); \
     __ dmb(ISH);                                                      \
   } while (0)
 
+#define ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(load_instr, store_instr)             \
+  do {                                                                        \
+    Label exchange;                                                           \
+    __ dmb(ISH);                                                              \
+    __ bind(&exchange);                                                       \
+    __ add(i.TempRegister(0), i.InputRegister(0), i.InputRegister(1));        \
+    __ load_instr(i.OutputRegister(0), i.TempRegister(0));                    \
+    __ store_instr(i.TempRegister(0), i.InputRegister(2), i.TempRegister(0)); \
+    __ cmp(i.TempRegister(0), Operand(0));                                    \
+    __ b(ne, &exchange);                                                      \
+    __ dmb(ISH);                                                              \
+  } while (0)
+
 #define ASSEMBLE_IEEE754_BINOP(name)                                           \
   do {                                                                         \
     /* TODO(bmeurer): We should really get rid of this special instruction, */ \
     /* and generate a CallAddress instruction instead. */                      \
     FrameScope scope(masm(), StackFrame::MANUAL);                              \
     __ PrepareCallCFunction(0, 2, kScratchReg);                                \
     __ MovToFloatParameters(i.InputDoubleRegister(0),                          \
                             i.InputDoubleRegister(1));                         \
     __ CallCFunction(ExternalReference::ieee754_##name##_function(isolate()),  \
                      0, 2);                                                    \
@@ skipping 1562 matching lines @@
 
     case kAtomicStoreWord8:
       ASSEMBLE_ATOMIC_STORE_INTEGER(strb);
       break;
     case kAtomicStoreWord16:
       ASSEMBLE_ATOMIC_STORE_INTEGER(strh);
       break;
     case kAtomicStoreWord32:
       ASSEMBLE_ATOMIC_STORE_INTEGER(str);
       break;
+    case kAtomicExchangeInt8:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldrexb, strexb);
+      __ sxtb(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeUint8:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldrexb, strexb);
+      __ uxtb(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeInt16:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldrexh, strexh);
+      __ sxth(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeUint16:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldrexh, strexh);
+      __ uxth(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeWord32:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldrex, strex);
+      break;
   }
   return kSuccess;
 }  // NOLINT(readability/fn_size)
 
 
 // Assembles branches after an instruction.
 void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
   ArmOperandConverter i(this, instr);
   Label* tlabel = branch->true_label;
   Label* flabel = branch->false_label;
@@ skipping 584 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8