atomic_flag_test_and_set function fix.

should call atomic_compare_exchange_strong instead of the gen type call.

v2: still use __gen_ocl_atomic_compare_exchange_strong32 to implement
the atomic_flag_test_and_set function as the spec says:
"Returns atomically, the value of the object immediately
before the effects."
so if the flag old value is 0, should return 0 after calling
atomic_flag_test_and_set, if the flag old value is 1 should return 1.
secondly, cmpxchg instruction return a struct of {i32, i1}, also handle it
in gen backend.
this patch could fix the latest atomic_flag subset of conformance test.

Signed-off-by: Luo Xionghu <xionghu.luo@intel.com>
Reviewed-by: "Yang, Rong R" <rong.r.yang@intel.com>

2 files changed, 26 insertions, 5 deletions

diff --git a/backend/src/libocl/src/ocl_atom.cl b/backend/src/libocl/src/ocl_atom.cl
index e0af560a..b49aef3a 100644
--- a/backend/src/libocl/src/ocl_atom.cl
+++ b/backend/src/libocl/src/ocl_atom.cl
@@ -331,17 +331,35 @@ DECL_ATOMIC_LOAD_TYPE(load_explicit, fetch_addf, atomic_float, atomic_int, float
 
 OVERLOADABLE bool atomic_flag_test_and_set(volatile atomic_flag *object) {
   atomic_int * temp = (atomic_int*)object;
-  return (bool)__gen_ocl_atomic_compare_exchange_strong32(temp, 0, 1, memory_order_seq_cst, memory_order_seq_cst, memory_scope_device);
+  int expected = 0;
+  int new_value = 1;
+  int oldValue = __gen_ocl_atomic_compare_exchange_strong32(temp, expected, new_value, memory_order_seq_cst, memory_order_seq_cst, memory_scope_device);
+  if(oldValue == new_value)
+    return true;
+  else
+    return false;
 }
 
 OVERLOADABLE bool atomic_flag_test_and_set_explicit(volatile atomic_flag *object, memory_order order) {
   atomic_int * temp = (atomic_int*)object;
-  return (bool)__gen_ocl_atomic_compare_exchange_strong32(temp, 0, 1, memory_order_seq_cst, memory_order_seq_cst, memory_scope_device);
+  int expected = 0;
+  int new_value = 1;
+  int oldValue = __gen_ocl_atomic_compare_exchange_strong32(temp, expected, new_value, memory_order_seq_cst, memory_order_seq_cst, memory_scope_device);
+  if(oldValue == new_value)
+    return true;
+  else
+    return false;
 }
 
 OVERLOADABLE bool atomic_flag_test_and_set_explicit(volatile atomic_flag *object, memory_order order, memory_scope scope){
   atomic_int * temp = (atomic_int*)object;
-  return (bool)__gen_ocl_atomic_compare_exchange_strong32(temp, 0, 1, memory_order_seq_cst, memory_order_seq_cst, memory_scope_device);
+  int expected = 0;
+  int new_value = 1;
+  int oldValue = __gen_ocl_atomic_compare_exchange_strong32(temp, expected, new_value, memory_order_seq_cst, memory_order_seq_cst, memory_scope_device);
+  if(oldValue == new_value)
+    return true;
+  else
+    return false;
 }
 
 OVERLOADABLE void atomic_flag_clear(volatile atomic_flag *object){
diff --git a/backend/src/llvm/llvm_gen_backend.cpp b/backend/src/llvm/llvm_gen_backend.cpp
index 3d6261dd..b47805ba 100644
--- a/backend/src/llvm/llvm_gen_backend.cpp
+++ b/backend/src/llvm/llvm_gen_backend.cpp
@@ -3749,7 +3749,9 @@ namespace gbe
     ir::AtomicOps opcode = ir::ATOMIC_OP_CMPXCHG;
     uint32_t payloadNum = 0;
     vector<ir::Register> payload;
-    const ir::Register dst = this->getRegister(&I);
+    const ir::Register oldValue = this->getRegister(&I, 0);
+    const ir::Register compareRet = this->getRegister(&I, 1);
+    const ir::Register expected = this->getRegister(I.getCompareOperand());
 
     payload.push_back(this->getRegister(I.getCompareOperand()));
     payloadNum++;
@@ -3759,7 +3761,8 @@ namespace gbe
     const ir::Tuple payloadTuple = payloadNum == 0 ?
                                    ir::Tuple(0) :
                                    ctx.arrayTuple(&payload[0], payloadNum);
-    this->emitAtomicInstHelper(opcode, type, dst, llvmPtr, payloadTuple);
+    this->emitAtomicInstHelper(opcode, type, oldValue, llvmPtr, payloadTuple);
+    ctx.EQ(type, compareRet, oldValue, expected);
   }
 
   void GenWriter::regAllocateAtomicRMWInst(AtomicRMWInst &I) {