[ESIMD] Conditionally revert the recent changes for slm_gather() (#12341)

The previous fix (#12316) added usage
of llvm.masked.gather for slm_gather(). Such usage does not work with
current GPU drivers if ESIMD function is called via invoke_simd() API.

The fix here returns the previous lowering to GenX instead of
llvm.masked.gather.
Using the lowering to llvm.masked.gather can be used if define
__ESIMD_GATHER_SCATTER_LLVM_IR macro (turned off by default).

Signed-off-by: Klochkov, Vyacheslav N <[email protected]>

Author: v-klochkov

sycl/include/sycl/ext/intel/esimd/memory.hpp

@@ -3146,9 +3146,16 @@ slm_gather(simd<uint32_t, N> byte_offsets, simd_mask<N> mask,
       detail::getPropertyValue<PropertyListT, alignment_key>(sizeof(T));
   static_assert(Alignment >= sizeof(T),
                 "slm_gather() requires at least element-size alignment");
-  simd<MsgT, N> PassThru; // it is intentionally undefined
-  return __esimd_slm_gather_ld<MsgT, N, Alignment>(
-      byte_offsets.data(), mask.data(), PassThru.data());
+  if constexpr (detail::isMaskedGatherScatterLLVMAvailable()) {
+    simd<MsgT, N> PassThru; // it is intentionally undefined
+    return __esimd_slm_gather_ld<MsgT, N, Alignment>(
+        byte_offsets.data(), mask.data(), PassThru.data());
+  } else {
+    static_assert(N == 1 || N == 8 || N == 16 || N == 32,
+                  "Unsupported vector length");
+    detail::LocalAccessorMarker acc;
+    return detail::gather_impl<T, N>(acc, byte_offsets, 0, mask);
+  }
 }
 
 template <typename T, int N,

sycl/test-e2e/InvokeSimd/Regression/slm_gather_scatter.cpp

@@ -0,0 +1,155 @@
+// GPU driver had an error in handling of SLM aligned block_loads/stores,
+// which has been fixed only in "1.3.26816", and in win/opencl version going
+// _after_ 101.4575.
+// REQUIRES-INTEL-DRIVER: lin: 26816, win: 101.4576
+//
+// RUN: %{build} -fno-sycl-device-code-split-esimd -Xclang -fsycl-allow-func-ptr -o %t.out
+// RUN: env IGC_VCSaveStackCallLinkage=1 IGC_VCDirectCallsOnly=1 %{run} %t.out
+//
+// VISALTO enable run
+// RUN: env IGC_VISALTO=63 IGC_VCSaveStackCallLinkage=1 IGC_VCDirectCallsOnly=1 %{run} %t.out
+
+/*
+ * Test check basic support of local memory access in invoke_simd.
+ */
+
+#include "../invoke_simd_utils.hpp"
+
+#include <sycl/ext/intel/esimd.hpp>
+#include <sycl/ext/oneapi/experimental/invoke_simd.hpp>
+#include <sycl/sycl.hpp>
+
+#include <functional>
+#include <iostream>
+#include <type_traits>
+
+// TODO: When gpu driver can pass/accept accessor by value,
+// the work-around undef #ifdef US_ACC_PTR should be removed.
+#define USE_ACC_PTR
+
+/* Subgroup size attribute is optional
+ * In case it is absent compiler decides what subgroup size to use
+ */
+#ifdef IMPL_SUBGROUP
+#define SUBGROUP_ATTR
+#else
+#define SUBGROUP_ATTR [[intel::reqd_sub_group_size(VL)]]
+#endif
+
+using namespace sycl;
+using namespace sycl::ext::oneapi::experimental;
+namespace esimd = sycl::ext::intel::esimd;
+
+using dtype = int;
+
+constexpr int VL = 16;
+constexpr uint32_t LocalRange = VL * 2;          // 2 sub-groups per 1 group.
+constexpr uint32_t GlobalRange = LocalRange * 2; // 2 groups.
+
+ESIMD_INLINE void slm_load_store_test(
+    local_accessor<dtype, 1> LocalAcc, uint32_t LAByteOffset, dtype *A,
+    dtype *C, esimd::simd<uint32_t, VL> GlobalByteOffsets) SYCL_ESIMD_FUNCTION {
+
+  uint32_t LocalAccOffset =
+      static_cast<uint32_t>(
+          reinterpret_cast<std::uintptr_t>(LocalAcc.get_pointer().get())) +
+      LAByteOffset;
+  esimd::simd<uint32_t, VL> Offsets(LocalAccOffset, sizeof(dtype));
+  auto Local1 = esimd::slm_gather<dtype, VL>(Offsets);
+  Offsets += static_cast<uint32_t>(LocalRange * sizeof(dtype));
+  auto Local2 = esimd::slm_gather<dtype, VL>(Offsets);
+
+  auto Global = esimd::gather(A, GlobalByteOffsets);
+  auto Res = Global + Local1 + Local2;
+  esimd::slm_scatter(Offsets, Res);
+}
+
+[[intel::device_indirectly_callable]] SYCL_EXTERNAL void __regcall invoke_slm_load_store_test(
+#ifdef USE_ACC_PTR
+    local_accessor<dtype, 1> *LocalAcc,
+#else
+    local_accessor<dtype, 1> LocalAcc,
+#endif
+    uint32_t SLMByteOffset, dtype *A, dtype *C,
+    simd<uint32_t, VL> GlobalByteOffsets) SYCL_ESIMD_FUNCTION {
+#ifdef USE_ACC_PTR
+  slm_load_store_test(*LocalAcc, SLMByteOffset, A, C, GlobalByteOffsets);
+#else
+  slm_load_store_test(LocalAcc, SLMByteOffset, A, C, GlobalByteOffsets);
+#endif
+}
+
+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>()
+            << std::endl;
+
+  auto DeviceSLMSize = Dev.get_info<sycl::info::device::local_mem_size>();
+  std::cout << "Local Memory Size: " << DeviceSLMSize << std::endl;
+
+  sycl::nd_range<1> NDRange{range<1>{GlobalRange}, range<1>{LocalRange}};
+
+  // The test is going to use (LocalRange * 2) elements of dtype type.
+  if (DeviceSLMSize < LocalRange * 2 * sizeof(dtype)) {
+    // Report an error - the test needs a fix.
+    std::cerr << "Error: Test needs more SLM memory than device has"
+              << std::endl;
+    return 1;
+  }
+
+  auto *A = malloc_shared<dtype>(GlobalRange, Q);
+  auto *C = malloc_shared<dtype>(GlobalRange, Q);
+
+  for (auto i = 0; i < GlobalRange; i++) {
+    A[i] = i;
+    C[i] = 0;
+  }
+  try {
+    Q.submit([&](handler &CGH) {
+       auto LocalAcc = local_accessor<dtype, 1>(LocalRange * 2, CGH);
+       CGH.parallel_for(NDRange, [=](nd_item<1> Item) SUBGROUP_ATTR {
+         uint32_t GlobalId = Item.get_global_id(0);
+         uint32_t LocalId = Item.get_local_id(0);
+         auto LocalAccCopy = LocalAcc;
+         LocalAccCopy[LocalId] = GlobalId * 100;
+         LocalAccCopy[LocalId + LocalRange] = GlobalId * 10000;
+         Item.barrier();
+
+         uint32_t LAByteOffset = (LocalId / VL) * VL * sizeof(dtype);
+         uint32_t GlobalByteOffset = GlobalId * sizeof(dtype);
+         sycl::sub_group SG = Item.get_sub_group();
+#ifdef USE_ACC_PTR
+         auto LocalAccArg = uniform{&LocalAccCopy};
+#else
+         auto LocalAccArg = uniform{LocalAccCopy};
+#endif
+         invoke_simd(SG, invoke_slm_load_store_test, LocalAccArg,
+                     uniform{LAByteOffset}, uniform{A}, uniform{C},
+                     GlobalByteOffset);
+         C[GlobalId] = LocalAccCopy[LocalId + LocalRange];
+       });
+     }).wait();
+  } catch (sycl::exception const &e) {
+    std::cout << "SYCL exception caught: " << e.what() << '\n';
+    free(A, Q);
+    free(C, Q);
+    return e.code().value();
+  }
+
+  bool Pass = true;
+  for (auto i = 0; i < GlobalRange; i++) {
+    dtype Expected = A[i] + i * (10000 + 100);
+    if (C[i] != Expected) {
+      std::cout << "Error: C[" << i << "]:" << C[i]
+                << " != [expected]:" << Expected << std::endl;
+      Pass = false;
+    }
+  }
+
+  free(A, Q);
+  free(C, Q);
+
+  std::cout << "Test result: " << (Pass ? "Pass" : "Fail") << std::endl;
+  return Pass ? 0 : 1;
+}