[Beignet] [Patch v2 2/2] [OCL20] atomic_flag_test_and_set function fix.

[xionghu.luo at intel.com]

From: Luo Xionghu <xionghu.luo at intel.com>

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.
---
 backend/src/libocl/src/ocl_atom.cl    | 24 +++++++++++++++++++++---
 backend/src/llvm/llvm_gen_backend.cpp |  7 +++++--
 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 e0af560..b49aef3 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 6646536..de3aa4c 100644
--- a/backend/src/llvm/llvm_gen_backend.cpp
+++ b/backend/src/llvm/llvm_gen_backend.cpp
@@ -3690,7 +3690,9 @@ 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++;
@@ -3700,7 +3702,8 @@ 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) {
-- 
2.1.4