[SYCL] Change library loading and fix esimd selector function (#1312)

The esimd_test_utils.hpp file has been changed to provide a correct esimd_emulator selector and the library_loading.cpp has been changed to only check for esimd_emulator loading if the filter is set to esimd_emulator. This checks the functionality introduced in the following PR: intel/llvm#6870

Author: lbushi25

SYCL/Basic/library_loading.cpp

@@ -1,17 +1,20 @@
 // REQUIRES: linux
 // RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %s -o %t.out
-// RUN: env SYCL_PI_TRACE=-1 %t.out &> %t_trace.txt || true
-// RUN: FileCheck --input-file=%t_trace.txt %s
-
+// RUN: env SYCL_PI_TRACE=-1 %t.out &> %t_trace_no_filter.txt || true
+// RUN: FileCheck --input-file=%t_trace_no_filter.txt --check-prefix=CHECK-NO-FILTER %s
+// RUN: env SYCL_PI_TRACE=-1 SYCL_DEVICE_FILTER=esimd_emulator %t.out &> %t_trace_esimd_filter.txt || true
+// RUN: FileCheck --input-file=%t_trace_esimd_filter.txt --check-prefix=CHECK-ESIMD-FILTER %s
 // Checks pi traces on library loading
+
 #include <sycl/sycl.hpp>
 
 using namespace sycl;
 
 int main() {
-  // CHECK: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_cuda.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_cuda.so)}}
-  // CHECK: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_hip.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_hip.so)}}
-  // CHECK: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_esimd_emulator.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_esimd_emulator.so)}}
+  // CHECK-NO-FILTER: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_cuda.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_cuda.so)}}
+  // CHECK-NO-FILTER-NOT: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_esimd_emulator.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_esimd_emulator.so)}}
+  // CHECK-NO-FILTER: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_hip.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_hip.so)}}
+  // CHECK-ESIMD-FILTER: {{(SYCL_PI_TRACE\[-1\]: dlopen\(.*/libpi_esimd_emulator.so\) failed with)|(SYCL_PI_TRACE\[basic\]: Plugin found and successfully loaded: libpi_esimd_emulator.so)}}
   queue q;
   q.submit([&](handler &cgh) {});
 }

SYCL/ESIMD/esimd_test_utils.hpp

@@ -26,26 +26,28 @@ using namespace sycl;
 
 namespace esimd_test {
 
-// This is function provided to SYCL runtime by the application to decide
+// This is the function provided to SYCL runtime by the application to decide
 // on which device to run, or whether to run at all.
 // When selecting a device, SYCL runtime first takes (1) a selector provided by
 // the program or a default one and (2) the set of all available devices. Then
-// it passes each device to the selector. A device for which the highest number
-// is returned is selected. If a negative number was returned for all devices,
-// then the selection process will cause an exception.
+// it passes each device to the '()' operator of the selector. Device, for
+// which '()' returned the highest number, is selected. If a negative number
+// was returned for all devices, then the selection process will cause an
+// exception.
+// Require GPU device
 inline int ESIMDSelector(const device &device) {
-  if (const char *dev_filter = getenv("SYCL_DEVICE_FILTER")) {
-    std::string filter_string(dev_filter);
-    if (filter_string.find("gpu") != std::string::npos)
-      return device.is_gpu() ? 1000 : -1;
-
-    std::cerr
-        << "Supported 'SYCL_DEVICE_FILTER' env var device type is 'gpu' and "
-        << filter_string << "' does not contain that.\n";
+  const std::string intel{"Intel(R) Corporation"};
+  if (device.get_backend() == backend::ext_intel_esimd_emulator) {
+    return 1000;
+  } else if (device.is_gpu() &&
+             (device.get_info<info::device::vendor>() == intel)) {
+    // pick gpu device if esimd not available but give it a lower score in
+    // order not to compete with the esimd in environments where both are
+    // present
+    return 900;
+  } else {
     return -1;
   }
-  // If "SYCL_DEVICE_FILTER" not defined, only allow gpu device
-  return device.is_gpu() ? 1000 : -1;
 }
 
 inline auto createExceptionHandler() {