[NFCI][SYCL] Remove boost::mp11 dependency from invoke_simd.hpp (#15713)

C++17 implementation is about as readable as boost-based one, and we
want to drop the external boost dependency for upstreaming purposes.

Author: aelovikov-intel

sycl/include/sycl/detail/helpers.hpp

@@ -240,11 +240,11 @@ getSPIRVMemorySemanticsMask(const access::fence_space AccessSpace,
 
 // To ensure loop unrolling is done when processing dimensions.
 template <size_t... Inds, class F>
-void loop_impl(std::integer_sequence<size_t, Inds...>, F &&f) {
+constexpr void loop_impl(std::integer_sequence<size_t, Inds...>, F &&f) {
   (f(std::integral_constant<size_t, Inds>{}), ...);
 }
 
-template <size_t count, class F> void loop(F &&f) {
+template <size_t count, class F> constexpr void loop(F &&f) {
   loop_impl(std::make_index_sequence<count>{}, std::forward<F>(f));
 }
 inline constexpr bool is_power_of_two(int x) { return (x & (x - 1)) == 0; }

sycl/include/sycl/ext/oneapi/experimental/invoke_simd.hpp

@@ -14,7 +14,6 @@
 #include <sycl/ext/oneapi/experimental/detail/invoke_simd_types.hpp>
 #include <sycl/ext/oneapi/experimental/uniform.hpp>
 
-#include <sycl/detail/boost/mp11.hpp>
 #include <sycl/sub_group.hpp>
 
 #include <functional>
@@ -71,8 +70,6 @@ namespace ext::oneapi::experimental {
 // --- Helpers
 namespace detail {
 
-namespace __MP11_NS = sycl::detail::boost::mp11;
-
 // This structure performs the SPMD-to-SIMD parameter type conversion as defined
 // by the spec.
 template <class T, int N, class = void> struct spmd2simd;
@@ -154,8 +151,7 @@ struct is_simd_or_mask_type<simd_mask<T, N>> : std::true_type {};
 // Checks if all the types in the parameter pack are uniform<T>.
 template <class... SpmdArgs> struct all_uniform_types {
   constexpr operator bool() {
-    using TypeList = __MP11_NS::mp_list<SpmdArgs...>;
-    return __MP11_NS::mp_all_of<TypeList, is_uniform_type>::value;
+    return ((is_uniform_type<SpmdArgs>::value && ...));
   }
 };
 
@@ -193,26 +189,32 @@ constexpr void verify_return_type_matches_sg_size() {
 // as prescribed by the spec assuming this subgroup size. One and only one
 // subgroup size should conform.
 template <class SimdCallable, class... SpmdArgs> struct sg_size {
-  template <class N>
-  using IsInvocableSgSize = __MP11_NS::mp_bool<std::is_invocable_v<
-      SimdCallable, typename spmd2simd<SpmdArgs, N::value>::type...>>;
-
   __DPCPP_SYCL_EXTERNAL constexpr operator int() {
-    using SupportedSgSizes = __MP11_NS::mp_list_c<int, 1, 2, 4, 8, 16, 32>;
-    using InvocableSgSizes =
-        __MP11_NS::mp_copy_if<SupportedSgSizes, IsInvocableSgSize>;
-    constexpr auto found_invoke_simd_target =
-        __MP11_NS::mp_empty<InvocableSgSizes>::value != 1;
-    if constexpr (found_invoke_simd_target) {
-      static_assert((__MP11_NS::mp_size<InvocableSgSizes>::value == 1) &&
-                    "multiple invoke_simd targets found");
-      return __MP11_NS::mp_front<InvocableSgSizes>::value;
-    }
-    static_assert(
-        found_invoke_simd_target,
-        "No callable invoke_simd target found. Confirm the "
-        "invoke_simd invocation argument types are convertible to the "
-        "invoke_simd target argument types");
+    constexpr auto x = []() constexpr {
+      constexpr int supported_sg_sizes[] = {1, 2, 4, 8, 16, 32};
+      int num_found = 0;
+      int found_sg_size = 0;
+      sycl::detail::loop<std::size(supported_sg_sizes)>([&](auto idx) {
+        constexpr auto sg_size = supported_sg_sizes[idx];
+        if (std::is_invocable_v<
+                SimdCallable, typename spmd2simd<SpmdArgs, sg_size>::type...>) {
+          ++num_found;
+          found_sg_size = sg_size;
+        }
+      });
+      return std::pair{num_found, found_sg_size};
+    }();
+
+    constexpr auto num_found = x.first;
+    constexpr auto found_sg_size = x.second;
+
+    static_assert(num_found != 0,
+                  "No callable invoke_simd target found. Confirm the "
+                  "invoke_simd invocation argument types are convertible to "
+                  "the invoke_simd target argument types");
+    static_assert(num_found == 1, "Multiple invoke_simd targets found!");
+
+    return found_sg_size;
   }
 };
 

sycl/test/invoke_simd/no_callee_found.cpp

@@ -26,5 +26,5 @@ void foo() {
 
 int main() {
   foo();
-  // CHECK: {{.*}}error:{{.*}}static assertion failed due to requirement 'found_invoke_simd_target': No callable invoke_simd target found. Confirm the invoke_simd invocation argument types are convertible to the invoke_simd target argument types{{.*}}
+  // CHECK: {{.*}}error:{{.*}}static assertion failed due to requirement 'num_found != 0': No callable invoke_simd target found. Confirm the invoke_simd invocation argument types are convertible to the invoke_simd target argument types{{.*}}
 }