[SYCL][API Simplification] Make flattened parallel_fors use const ref vecs (#1043)

* Const ref is the better path.
* Use vector_class

Signed-off-by: James Brodman <[email protected]>

Author: jbrodman

sycl/include/CL/sycl/queue.hpp

@@ -149,7 +149,8 @@ class queue {
   /// @param DepEvents is a vector of events that specify the kernel dependences
   /// @param KernelFunc is the Kernel functor or lambda
   template <typename KernelName = detail::auto_name, typename KernelType>
-  event single_task(std::vector<event> DepEvents, KernelType KernelFunc) {
+  event single_task(const vector_class<event> &DepEvents,
+                    KernelType KernelFunc) {
     return submit([&](handler &CGH) {
       CGH.depends_on(DepEvents);
       CGH.template single_task<KernelName, KernelType>(KernelFunc);
@@ -195,7 +196,8 @@ class queue {
   /// @param KernelFunc is the Kernel functor or lambda
   template <typename KernelName = detail::auto_name, typename KernelType,
             int Dims>
-  event parallel_for(range<Dims> NumWorkItems, std::vector<event> DepEvents,
+  event parallel_for(range<Dims> NumWorkItems,
+                     const vector_class<event> &DepEvents,
                      KernelType KernelFunc) {
     return submit([&](handler &CGH) {
       CGH.depends_on(DepEvents);
@@ -248,7 +250,8 @@ class queue {
   template <typename KernelName = detail::auto_name, typename KernelType,
             int Dims>
   event parallel_for(range<Dims> NumWorkItems, id<Dims> WorkItemOffset,
-                     std::vector<event> DepEvents, KernelType KernelFunc) {
+                     const vector_class<event> &DepEvents,
+                     KernelType KernelFunc) {
     return submit([&](handler &CGH) {
       CGH.depends_on(DepEvents);
       CGH.template parallel_for<KernelName, KernelType, Dims>(
@@ -296,7 +299,8 @@ class queue {
   template <typename KernelName = detail::auto_name, typename KernelType,
             int Dims>
   event parallel_for(nd_range<Dims> ExecutionRange,
-                     std::vector<event> DepEvents, KernelType KernelFunc) {
+                     const vector_class<event> &DepEvents,
+                     KernelType KernelFunc) {
     return submit([&](handler &CGH) {
       CGH.depends_on(DepEvents);
       CGH.template parallel_for<KernelName, KernelType, Dims>(ExecutionRange,

sycl/test/usm/pfor_flatten.cpp

@@ -47,12 +47,14 @@ int main() {
         array[i]++;
       });
 
-  q.single_task({e3}, [=]() {
+  auto e4 = q.single_task({e3}, [=]() {
     for (int i = 0; i < N; i++) {
       array[i]++;
     }
   });
 
+  q.single_task(e4, [=]() { array[0] = array[0]; });
+
   q.wait();
 
   for (int i = 0; i < N; i++) {