S390: [Atomics] Remove Atomics code stubs; use TF ops

src/compiler/s390/code-generator-s390.cc

Index: src/compiler/s390/code-generator-s390.cc
diff --git a/src/compiler/s390/code-generator-s390.cc b/src/compiler/s390/code-generator-s390.cc
index 3ebe0827482bd7bc6055c2bb7cde94cbe8dbb68a..bffdc93916f7d68991842d92678693fcb1d11012 100644
--- a/src/compiler/s390/code-generator-s390.cc
+++ b/src/compiler/s390/code-generator-s390.cc
@@ -67,8 +67,8 @@ class S390OperandConverter final : public InstructionOperandConverter {
 
   MemOperand MemoryOperand(AddressingMode* mode, size_t* first_index) {
     const size_t index = *first_index;
-    *mode = AddressingModeField::decode(instr_->opcode());
-    switch (*mode) {
+    if (mode) *mode = AddressingModeField::decode(instr_->opcode());
+    switch (AddressingModeField::decode(instr_->opcode())) {
       case kMode_None:
         break;
       case kMode_MRI:
@@ -82,7 +82,8 @@ class S390OperandConverter final : public InstructionOperandConverter {
     return MemOperand(r0);
   }
 
-  MemOperand MemoryOperand(AddressingMode* mode, size_t first_index = 0) {
+  MemOperand MemoryOperand(AddressingMode* mode = NULL,
+                           size_t first_index = 0) {
     return MemoryOperand(mode, &first_index);
   }
 
@@ -1660,6 +1661,22 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kCheckedStoreFloat64:
       ASSEMBLE_CHECKED_STORE_DOUBLE();
       break;
+    case kAtomicLoadInt8:
+      __ LoadB(i.OutputRegister(), i.MemoryOperand());
+      break;
+    case kAtomicLoadUint8:
+      __ LoadlB(i.OutputRegister(), i.MemoryOperand());
+      break;
+    case kAtomicLoadInt16:
+      __ LoadHalfWordP(i.OutputRegister(), i.MemoryOperand());
+      break;
+    case kAtomicLoadUint16:
+      // ASSEMBLE_ATOMIC_LOAD_INTEGER(lhz, lhzx);

[JoranSiu, 2016/04/19 21:02:49]

Can we remove this unnecessary comment?

+      __ llgh(i.OutputRegister(), i.MemoryOperand());

[JoranSiu, 2016/04/19 21:02:49]

Should this be calling LoadLogicialHalfwordP (i.e. llh on 31-bit, llgh on
64-bit).

+      break;
+    case kAtomicLoadWord32:
+      __ lgf(i.OutputRegister(), i.MemoryOperand());

[JoranSiu, 2016/04/19 21:02:49]

Should this be Load():  L on 31-bit, LGF on 64-bit? 

+      break;
     default:
       UNREACHABLE();
       break;