[Atomics] Make Atomics.exchange a builtin using TF

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index 1a7bed140788d164911bd8a9fc22134bef1a1af4..f144ccf5334acbc5969d48ccabf715ee636ca613 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -1888,24 +1888,6 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       }
       break;
     }
-    case kIA32Xchgb: {
-      size_t index = 0;
-      Operand operand = i.MemoryOperand(&index);
-      __ xchg_b(i.InputRegister(index), operand);
-      break;
-    }
-    case kIA32Xchgw: {
-      size_t index = 0;
-      Operand operand = i.MemoryOperand(&index);
-      __ xchg_w(i.InputRegister(index), operand);
-      break;
-    }
-    case kIA32Xchgl: {
-      size_t index = 0;
-      Operand operand = i.MemoryOperand(&index);
-      __ xchg(i.InputRegister(index), operand);
-      break;
-    }
     case kCheckedLoadInt8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(movsx_b);
       break;
@@ -1952,6 +1934,40 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
     case kCheckedStoreWord64:
       UNREACHABLE();  // currently unsupported checked int64 load/store.
       break;
+#define EXCHANGE_OPERANDS                \
+  size_t index = 0;                      \
+  Register r = i.InputRegister(index++); \
+  Operand operand = i.MemoryOperand(&index);

[binji, 2017/02/22 02:08:38]

looks like if index is not used afterward it is simpler to just use
i.InputRegister(0) and i.MemoryOperand(1), then you can ditch the macro (as it
doesn't seem to be a common pattern in this file)

[aseemgarg, 2017/02/22 03:29:02]

Done.

+    case kAtomicExchangeInt8: {
+      EXCHANGE_OPERANDS
+      __ xchg_b(r, operand);
+      __ movsx_b(r, r);
+      break;
+    }
+    case kAtomicExchangeUint8: {
+      EXCHANGE_OPERANDS
+      __ xchg_b(r, operand);
+      __ movzx_b(r, r);
+      break;
+    }
+    case kAtomicExchangeInt16: {
+      EXCHANGE_OPERANDS
+      __ xchg_w(r, operand);
+      __ movsx_w(r, r);
+      break;
+    }
+    case kAtomicExchangeUint16: {
+      EXCHANGE_OPERANDS
+      __ xchg_w(r, operand);
+      __ movzx_w(r, r);
+      break;
+    }
+    case kAtomicExchangeWord32: {
+      EXCHANGE_OPERANDS
+      __ xchg(r, operand);
+      break;
+    }
+#undef EXCHANGE_OPERANDS
     case kAtomicLoadInt8:
     case kAtomicLoadUint8:
     case kAtomicLoadInt16: