[SYCL][ESIMD][Doc] Add invoke_simd example (#10052)

This change adds an invoke_simd example that scales the input data and
updates related doc to point to it.

---------

Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>

sycl/doc/extensions/supported/sycl_ext_intel_esimd/README.md

@@ -84,7 +84,11 @@ the same application.
 ### SYCL and ESIMD interoperability
 
 SYCL kernels can call ESIMD functions using the special `invoke_simd` API.
+
+More examples are available [here](./examples/)
+
 More details are available in [invoke_simd spec](../../experimental/sycl_ext_oneapi_invoke_simd.asciidoc)
+
 Test cases are available [here](../../../../test-e2e/InvokeSimd/)
 
 ```cpp

sycl/doc/extensions/supported/sycl_ext_intel_esimd/examples/README.md

@@ -26,5 +26,43 @@ is to show the basic ESIMD APIs in well known examples.
      });
    }).wait_and_throw();
    ```
+2) Calling ESIMD from SYCL using invoke_simd - ["invoke_simd"](./invoke_simd.md).
+   Please see the full source code here: ["invoke_simd"](./invoke_simd.md)
+   ```c++
+   [[intel::device_indirectly_callable]] simd<int, VL> __regcall scale(
+     simd<int, VL> x, int n) SYCL_ESIMD_FUNCTION {
+     esimd::simd<int, VL> vec = x;
+     esimd::simd<int, VL> result = vec * n;
+    return result;
+   }
+
+   int main(void) { 
+     int *in = new int[SIZE];
+     int *out = new int[SIZE];
+     buffer<int, 1> bufin(in, range<1>(SIZE));
+     buffer<int, 1> bufout(out, range<1>(SIZE));
+
+     // scale factor
+     int n = 2;
+
+     sycl::range<1> GlobalRange{SIZE};
+     sycl::range<1> LocalRange{VL};
+    
+     q.submit([&](handler &cgh) {
+      auto accin = bufin.get_access<access::mode::read>(cgh);
+      auto accout = bufout.get_access<access::mode::write>(cgh);
+
+      cgh.parallel_for<class Scale>(
+          nd_range<1>(GlobalRange, LocalRange), [=](nd_item<1> item) {
+            sycl::sub_group sg = item.get_sub_group();
+            unsigned int offset = item.get_global_linear_id();
+
+            int in_val = sg.load(accin.get_pointer() + offset);
+
+            int out_val = invoke_simd(sg, scale, in_val, uniform{n});
 
-2) TODO: Add more examples here.
+            sg.store(accout.get_pointer() + offset, out_val);
+          });
+    });
+    ```
+3) TODO: Add more examples here.

sycl/doc/extensions/supported/sycl_ext_intel_esimd/examples/invoke_simd.md

@@ -0,0 +1,95 @@
+## Call ESIMD from SYCL using invoke_simd
+
+In this example, we will scale the input data by a factor of 2 using `invoke_simd`.
+
+Compile and run:
+```bash
+> clang++ -fsycl -fno-sycl-device-code-split-esimd -Xclang -fsycl-allow-func-ptr invoke_simd.cpp
+
+> IGC_VCSaveStackCallLinkage=1 IGC_VCDirectCallsOnly=1 ONEAPI_DEVICE_SELECTOR=level_zero:gpu ./a.out
+Running on Intel(R) UHD Graphics 630
+Passed
+```
+Source code:
+```c++
+#include <sycl/ext/intel/esimd.hpp>
+#include <sycl/ext/oneapi/experimental/invoke_simd.hpp>
+#include <sycl/sycl.hpp>
+#include <iostream>
+
+using namespace sycl;
+using namespace sycl::ext::oneapi::experimental;
+namespace esimd = sycl::ext::intel::esimd;
+
+constexpr int SIZE = 512;
+constexpr int VL = 16;
+
+[[intel::device_indirectly_callable]] simd<int, VL> __regcall scale(
+    simd<int, VL> x, int n) SYCL_ESIMD_FUNCTION {
+  esimd::simd<int, VL> vec = x;
+  esimd::simd<int, VL> result = vec * n;
+  return result;
+}
+
+int main(void) {
+  auto q = queue{gpu_selector_v};
+  auto dev = q.get_device();
+  std::cout << "Running on " << dev.get_info<sycl::info::device::name>()
+            << "\n";
+  bool passed = true;
+  int *in = new int[SIZE];
+  int *out = new int[SIZE];
+
+  for (int i = 0; i < SIZE; ++i) {
+    in[i] = i;
+    out[i] = 0;
+  }
+
+  // scale factor
+  int n = 2;
+
+  try {
+    buffer<int, 1> bufin(in, range<1>(SIZE));
+    buffer<int, 1> bufout(out, range<1>(SIZE));
+
+    sycl::range<1> GlobalRange{SIZE};
+    sycl::range<1> LocalRange{VL};
+
+    auto e = q.submit([&](handler &cgh) {
+      auto accin = bufin.get_access<access::mode::read>(cgh);
+      auto accout = bufout.get_access<access::mode::write>(cgh);
+
+      cgh.parallel_for<class Scale>(
+          nd_range<1>(GlobalRange, LocalRange), [=](nd_item<1> item) {
+            sycl::sub_group sg = item.get_sub_group();
+            unsigned int offset = item.get_global_linear_id();
+
+            int in_val = sg.load(accin.get_pointer() + offset);
+
+            int out_val = invoke_simd(sg, scale, in_val, uniform{n});
+
+            sg.store(accout.get_pointer() + offset, out_val);
+          });
+    });
+    e.wait();
+  } catch (sycl::exception const &e) {
+    delete[] in;
+    delete[] out;
+    std::cout << "SYCL exception caught: " << e.what() << '\n';
+    return 1;
+  }
+
+  for (int i = 0; i < SIZE; ++i) {
+    if (out[i] != in[i] * n) {
+      std::cout << "failed at index " << i << ", " << out[i] << " != " << in[i]
+                << " * " << n << "\n";
+      passed = false;
+    }
+  }
+  delete[] in;
+  delete[] out;
+  std::cout << (passed ? "Passed\n" : "FAILED\n");
+  return passed ? 0 : 1;
+}
+
+```