Add atomic intrinsic for output nonzero inference. (#25)

* upd

* upd

include/tvm/tir/builtin.h

@@ -504,6 +504,11 @@ TVM_DLL const Op& tvm_lower_bound();
  */
 TVM_DLL const Op& tvm_upper_bound();
 
+/*!
+ * \brief Atomic add function.
+ */
+TVM_DLL const Op& tvm_atomic_add();
+
 /*!
  * \brief Initialize the global barrier.
  *  Call this at beginning of kernel that need global barrier.

include/tvm/tir/op.h

@@ -817,6 +817,14 @@ TVM_DLL PrimExpr lower_bound(tir::Var arr, PrimExpr val, PrimExpr l, PrimExpr r,
 TVM_DLL PrimExpr upper_bound(tir::Var arr, PrimExpr val, PrimExpr l, PrimExpr r,
                              Span span = Span());
 
+/*!
+ * \brief Perform atomic add on ptr by val, and return the old value.
+ * \param ptr The address to perform atomic add.
+ * \param val The value to add.
+ * \return The old result stored in ptr.
+ */
+TVM_DLL PrimExpr atomic_add(tir::Var ptr, PrimExpr val, Span span = Span());
+
 /*!
  * \brief Calculate trunc(x)
  * \param x The input expression.

python/tvm/script/tir/intrin.py

@@ -130,6 +130,11 @@ def upper_bound(arr, val, l, r, span):
     return tvm.tir.upper_bound(arr, val, l, r, span)
 
 
+@register
+def atomic_add(ptr, val, span):
+    return tvm.tir.atomic_add(ptr, val, span)
+
+
 @register
 def floordiv(x, y, span):
     return tvm.tir.floordiv(x, y, span)

python/tvm/tir/__init__.py

@@ -37,7 +37,7 @@
 from .function import PrimFunc
 
 from .op import call_packed, call_intrin, call_pure_extern, call_extern
-from .op import call_llvm_intrin, call_llvm_pure_intrin, ret, all, any, min_value, max_value, trace, lower_bound, upper_bound
+from .op import call_llvm_intrin, call_llvm_pure_intrin, ret, all, any, min_value, max_value, trace, lower_bound, upper_bound, atomic_add
 from .op import exp, exp2, exp10, log, log2, log10, log1p, ldexp, clz
 from .op import sin, sinh, asin, asinh
 from .op import cos, cosh, acos, acosh

python/tvm/tir/op.py

@@ -1027,6 +1027,26 @@ def upper_bound(arr, val, l, r, span=None):
     return _ffi_api.upper_bound(arr, val, l, r, span)  # type: ignore
 
 
+def atomic_add(ptr, val, span=None):
+    """Perform an atomic add operation to ptr by the given val.
+
+    Parameters
+    ----------
+    ptr : Var
+        The pointer to the address we perform atomic add.
+    val : PrimExpr
+        The value to add.
+    span : Optional[Span]
+        The location of this expression in the source code.
+
+    Returns
+    -------
+    PrimExpr
+        The value on pointer before we perform the atomic add.
+    """
+    return _ffi_api.atomic_add(ptr, val, span)  # type: ignore
+
+
 def isnan(x, span=None):
     """Check if input value is Nan.
 

src/target/source/codegen_cuda.cc

@@ -752,6 +752,13 @@ void CodeGenCUDA::VisitExpr_(const CallNode* op, std::ostream& os) {
     os << ", ";
     this->PrintExpr(op->args[3], os);
     os << ")";
+  } else if (op->op.same_as(builtin::tvm_atomic_add())) {
+    os << "atomicAdd(";
+    ICHECK_EQ(op->args.size(), 2U);
+    this->PrintExpr(op->args[0], os);
+    os << ", ";
+    this->PrintExpr(op->args[1], os);
+    os << ")";
   } else {
     CodeGenC::VisitExpr_(op, os);
   }

src/tir/op/builtin.cc

@@ -228,6 +228,9 @@ TIR_DEFINE_BUILTIN_FUNC(tvm_lower_bound)
 TIR_DEFINE_BUILTIN_FUNC(tvm_upper_bound)
     .set_attr<TCallEffectKind>("TCallEffectKind", Integer(CallEffectKind::kOpaque));
 
+TIR_DEFINE_BUILTIN_FUNC(tvm_atomic_add)
+    .set_attr<TCallEffectKind>("TCallEffectKind", Integer(CallEffectKind::kOpaque));
+
 TIR_DEFINE_BUILTIN_FUNC(tvm_mma_sync)
     .set_attr<TCallEffectKind>("TCallEffectKind", Integer(CallEffectKind::kOpaque));
 

src/tir/op/op.cc

@@ -814,6 +814,11 @@ PrimExpr upper_bound(tir::Var arr, PrimExpr val, PrimExpr l, PrimExpr r, Span sp
   return tir::Call({kDLInt, 32, 1}, builtin::tvm_upper_bound(), {arr, val, l, r}, span);
 }
 
+// atomic_add
+PrimExpr atomic_add(tir::Var ptr, PrimExpr val, Span span) {
+  return tir::Call(val->dtype, builtin::tvm_atomic_add(), {ptr, val}, span);
+}
+
 // trunc
 PrimExpr trunc(PrimExpr x, Span span) {
   if (x.dtype().is_int() || x.dtype().is_uint()) {
@@ -932,6 +937,8 @@ TVM_REGISTER_GLOBAL("tir.lower_bound").set_body_typed(tvm::lower_bound);
 
 TVM_REGISTER_GLOBAL("tir.upper_bound").set_body_typed(tvm::upper_bound);
 
+TVM_REGISTER_GLOBAL("tir.atomic_add").set_body_typed(tvm::atomic_add);
+
 // operator overloading, smarter than make
 #define REGISTER_MAKE_BINARY_OP(Node, Func)                                                \
   TVM_REGISTER_GLOBAL("tir." #Node).set_body_typed([](PrimExpr a, PrimExpr b, Span span) { \

src/tir/schedule/analysis/analysis.cc

@@ -162,8 +162,16 @@ Definition of a scope that is a stage pipeline:
       if (!IsCompleteBlock(self, block_sref, scope_root_sref) &&
           !IsReductionBlock(self, block_sref, scope_root_sref)) {
         const BlockNode* block = TVM_SREF_TO_BLOCK(block, block_sref);
-        throw NotCompactDataFlowError(self->mod, GetRef<Stmt>(scope_root_subtree->stmt),
-                                      GetRef<Block>(block));
+        // NOTE(Zihao): check if the block has atomic attribute.
+        auto&& it = block->annotations.find("atomic");
+        bool is_atomic = false;
+        if (it != block->annotations.end()) {
+          is_atomic = ((*it).second).as<IntImmNode>()->value;
+        }
+        if (!is_atomic) {
+          throw NotCompactDataFlowError(self->mod, GetRef<Stmt>(scope_root_subtree->stmt),
+                                        GetRef<Block>(block));
+        }
       }
     }
   }

tests/python/unittest/test_tir_intrin.py

@@ -270,6 +270,20 @@ def binary_search(a: T.handle, b: T.handle, c: T.handle, d: T.handle) -> None:
             D[vi] = T.upper_bound(A.data, B[vi], 0, n)
 
 
+@T.prim_func
+def global_add(a: T.handle) -> None:
+    A = T.match_buffer(a, (1,), dtype='int32')
+    for i in T.serial(0, 1024):
+        with T.block('global_add'):
+            T.block_attr({
+                "atomic": True
+            })
+            T.reads([A[0:1]])
+            T.writes([A[0:1]])
+            vi = T.axis.S(1024, i)
+            T.evaluate(T.atomic_add(A.data, vi))
+
+
 def test_binary_search():
     sch = tir.Schedule(binary_search)
     b = sch.get_block('search')
@@ -281,7 +295,7 @@ def test_binary_search():
     # print(f.imported_modules[0].get_source())
 
     x = np.arange(-128, 128).astype(np.int32)
-    y = np.random.randint(-200, 200, size=1024).astype(np.int32) 
+    y = np.random.randint(-200, 200, size=1024).astype(np.int32)
     a = np.zeros((1024,)).astype(np.int32)
     b = np.zeros((1024,)).astype(np.int32)
 
@@ -293,7 +307,7 @@ def test_binary_search():
     dev = tvm.cuda(0)
     x_array = tvm.nd.array(x, device=dev)
     y_array = tvm.nd.array(y, device=dev)
-    a_array = tvm.nd.array(a, device=dev) 
+    a_array = tvm.nd.array(a, device=dev)
     b_array = tvm.nd.array(b, device=dev)
     f(x_array, y_array, a_array, b_array)
     tvm_a = a_array.numpy()
@@ -304,12 +318,30 @@ def test_binary_search():
     tvm.testing.assert_allclose(np_b, tvm_b)
 
 
+def test_global_add():
+    sch = tir.Schedule(global_add)
+    b = sch.get_block('global_add')
+    i, = sch.get_loops(b)
+    sch.bind(i, 'blockIdx.x')
+    f = tvm.build(sch.mod['main'], target='cuda')
+
+    # create input and run kernel
+    dev = tvm.cuda(0)
+    a = np.zeros((1,)).astype(np.int32)
+    a_gpu = tvm.nd.array(a, device=dev)
+    f(a_gpu)
+
+    # check output
+    tvm.testing.assert_allclose(a_gpu.numpy(), np.array([1024 * 1023 / 2]).astype(np.int32))
+
+
 if __name__ == "__main__":
     test_nearbyint()
     test_unary_intrin()
     test_round_intrinsics_on_int()
     test_binary_intrin()
     test_ldexp()
-    test_clz()
+    # test_clz()
     test_fma()
     test_binary_search()
+    test_global_add()