MIPS: [Atomics] Remove Atomics code stubs; use TF ops.

src/compiler/mips64/code-generator-mips64.cc

Index: src/compiler/mips64/code-generator-mips64.cc
diff --git a/src/compiler/mips64/code-generator-mips64.cc b/src/compiler/mips64/code-generator-mips64.cc
index 8004e7e3e4853d5c06f7af43bd217b4ef39d65c2..26684baf091bd871ff40b2d5bd8d6ffe276119b1 100644
--- a/src/compiler/mips64/code-generator-mips64.cc
+++ b/src/compiler/mips64/code-generator-mips64.cc
@@ -484,6 +484,12 @@ FPUCondition FlagsConditionToConditionCmpFPU(bool& predicate,
     __ bind(&done);                                                           \
   }
 
+#define ASSEMBLE_ATOMIC_LOAD_INTEGER(asm_instr)          \
+  do {                                                   \
+    __ asm_instr(i.OutputRegister(), i.MemoryOperand()); \
+    __ sync();                                           \
+  } while (0)
+
 void CodeGenerator::AssembleDeconstructFrame() {
   __ mov(sp, fp);
   __ Pop(ra, fp);
@@ -1575,12 +1581,19 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       ASSEMBLE_CHECKED_STORE_FLOAT(Double, sdc1);
       break;
     case kAtomicLoadInt8:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(lb);
+      break;
     case kAtomicLoadUint8:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(lbu);
+      break;
     case kAtomicLoadInt16:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(lh);
+      break;
     case kAtomicLoadUint16:
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(lhu);
+      break;
     case kAtomicLoadWord32:
-      // TODO(binji): implement
-      __ nop();
+      ASSEMBLE_ATOMIC_LOAD_INTEGER(lw);
       break;
   }
 }  // NOLINT(readability/fn_size)