[SYCL] Throw correct exception when passing unbound accessor to command (#8131)

According to 4.7.6.9 of SYCL2020 spec, if a placeholder accessor
is passed to a command without being bound to a command group, an
exception should be thrown. Prior to this change, the exception
was only thrown if an unbound placeholder accessor is used, not
only passed. Also, prior to this change, if we passed one unbound
accessor and one (or more) bound accessors to a command, the
exception thrown was incorrect.

Closes #3078.

---------

Signed-off-by: Maronas, Marcos <[email protected]>

Author: maarquitos14

sycl/source/detail/scheduler/commands.cpp

@@ -1978,10 +1978,8 @@ static pi_result SetKernelParamsAndLaunch(
       Requirement *Req = (Requirement *)(Arg.MPtr);
       if (Req->MAccessRange == range<3>({0, 0, 0}))
         break;
-      if (getMemAllocationFunc == nullptr)
-        throw sycl::exception(make_error_code(errc::kernel_argument),
-                              "placeholder accessor must be bound by calling "
-                              "handler::require() before it can be used.");
+      assert(getMemAllocationFunc != nullptr &&
+             "We should have caught this earlier.");
 
       RT::PiMem MemArg = (RT::PiMem)getMemAllocationFunc(Req);
       if (Plugin.getBackend() == backend::opencl) {

sycl/source/handler.cpp

@@ -94,6 +94,26 @@ event handler::finalize() {
     return MLastEvent;
   MIsFinalized = true;
 
+  // According to 4.7.6.9 of SYCL2020 spec, if a placeholder accessor is passed
+  // to a command without being bound to a command group, an exception should
+  // be thrown. There should be as many requirements as unique accessors,
+  // otherwise some of the accessors are unbound, and thus we throw.
+  {
+    // A counter is not good enough since we can have the same accessor several
+    // times as arg
+    std::unordered_set<void *> accessors;
+    for (const auto &arg : MArgs) {
+      if (arg.MType != detail::kernel_param_kind_t::kind_accessor)
+        continue;
+
+      accessors.insert(arg.MPtr);
+    }
+    if (accessors.size() > MRequirements.size())
+      throw sycl::exception(make_error_code(errc::kernel_argument),
+                            "placeholder accessor must be bound by calling "
+                            "handler::require() before it can be used.");
+  }
+
   const auto &type = getType();
   if (type == detail::CG::Kernel) {
     // If there were uses of set_specialization_constant build the kernel_bundle