[XPU] speed up for special case of strided_slice op. (#55166)

paddle/phi/kernels/xpu/stride_slice_grad_kernel.cc

@@ -16,6 +16,7 @@
 
 #include "paddle/phi/backends/xpu/enforce_xpu.h"
 #include "paddle/phi/core/kernel_registry.h"
+#include "paddle/phi/kernels/xpu/stride_slice_util.h"
 
 namespace phi {
 
@@ -77,6 +78,71 @@ void StridedSliceRawGradKernel(const Context& dev_ctx,
     strides_in[cur_axe] = strides_[i];
   }
 
+  if (is_strided_slice_special_case(xshape, starts_in, ends_in, strides_in)) {
+    PADDLE_ENFORCE_EQ(
+        x.numel(),
+        x_grad->numel(),
+        errors::PreconditionNotMet(
+            "x.numel() should be equal to x_grad->numel() in special case."));
+    PADDLE_ENFORCE_EQ(
+        x.numel(),
+        out_grad.numel() * 2,
+        errors::PreconditionNotMet("x.numel() should be equal to "
+                                   "out_grad->numel() * 2 in special case."));
+
+    /*
+     * sample input: [1 2 3 4 5]
+     * starts = [0/1]
+     * strides = [2]
+     * sample output: [1 0 2 0 3 0 4 0 5 0] (last value in starts is 0)
+     * sample output: [0 1 0 2 0 3 0 4 0 5] (last value in starts is 1)
+     */
+    xpu::ctx_guard RAII_GUARD(dev_ctx.x_context());
+    XPUType* x_transpose = RAII_GUARD.alloc_l3_or_gm<XPUType>(x.numel());
+
+    // step 1: set all value to 0
+
+    // int constant(Context* ctx, T* x, int len, T val)
+    int r = xpu::constant(
+        dev_ctx.x_context(), x_transpose, x.numel(), static_cast<XPUType>(0));
+    PADDLE_ENFORCE_XDNN_SUCCESS(r, "constant");
+
+    /*
+     * step 2: copy dy to dx:
+     * if starts from 0: [1 2 3 4 5 0 0 0 0 0]
+     * if starts from 1: [0 0 0 0 0 1 2 3 4 5]
+     */
+    int offset = 0;
+    if (starts_in.back() == 1) {
+      offset = x.numel() / 2;
+    }
+    // int copy(Context* ctx, const T* x, T* y, int64_t len)
+    r = xpu::copy<XPUType>(dev_ctx.x_context(),
+                           reinterpret_cast<const XPUType*>(out_grad.data<T>()),
+                           x_transpose + offset,
+                           x.numel() / 2);
+    PADDLE_ENFORCE_XDNN_SUCCESS(r, "copy");
+    /*
+     * step3: transpose, input shape is (2, x.numel/2):
+     * input:
+     * [1 2 3 4 5
+     *  0 0 0 0 0]
+     * after transpose:
+     * [1 0
+     *  2 0
+     *  3 0
+     *  4 0
+     *  5 0]
+     */
+    r = xpu::transpose<XPUType>(dev_ctx.x_context(),
+                                x_transpose,
+                                reinterpret_cast<XPUType*>(x_grad->data<T>()),
+                                {2, x.numel() / 2},
+                                {1, 0});
+    PADDLE_ENFORCE_XDNN_SUCCESS(r, "transpose");
+    return;
+  }
+
   int r = xpu::strided_slice_grad(
       dev_ctx.x_context(),
       reinterpret_cast<const XPUType*>(out_grad.data<T>()),

paddle/phi/kernels/xpu/stride_slice_kernel.cc

@@ -17,6 +17,7 @@
 #include "paddle/phi/backends/xpu/enforce_xpu.h"
 #include "paddle/phi/core/kernel_registry.h"
 #include "paddle/phi/kernels/funcs/strided_slice.h"
+#include "paddle/phi/kernels/xpu/stride_slice_util.h"
 
 namespace phi {
 
@@ -99,6 +100,57 @@ void StridedSliceRawKernel(const Context& dev_ctx,
     strides_in[cur_axe] = strides_[i];
   }
 
+  if (is_strided_slice_special_case(xshape, starts_in, ends_in, strides_in)) {
+    PADDLE_ENFORCE_EQ(
+        x.numel(),
+        out->numel() * 2,
+        errors::PreconditionNotMet(
+            "x.numel() should be equal to out->numel() * 2 in special case."));
+    /*
+     * sample input: [1 2 3 4 5 6 7 8 9 10]
+     * starts = [0/1]
+     * strides = [2]
+     * sample output: [1 3 5 7 9] (last value in starts is 0)
+     * sample output: [2 4 6 8 10] (last value in starts is 1)
+     */
+    xpu::ctx_guard RAII_GUARD(dev_ctx.x_context());
+    XPUType* x_transpose = RAII_GUARD.alloc_l3_or_gm<XPUType>(x.numel());
+    /*
+     * step 1: transpose, input shape is (x.numel/2, 2):
+     * input:
+     * [1 2
+     *  3 4
+     *  5 6
+     *  7 8
+     *  9 10]
+     * after transpose:
+     * [1 3 5 7 9
+     *  2 4 6 8 10]
+     */
+    // int transpose(Context* ctx, const T* x, T* y, const std::vector<int>&
+    // xshape, const std::vector<int>& permute)
+    int r =
+        xpu::transpose<XPUType>(dev_ctx.x_context(),
+                                reinterpret_cast<const XPUType*>(x.data<T>()),
+                                x_transpose,
+                                {x.numel() / 2, 2},
+                                {1, 0});
+    PADDLE_ENFORCE_XDNN_SUCCESS(r, "transpose");
+    // step 2: if starts from 0, use "first half" data as result, otherwise use
+    // "second half".
+    int offset = 0;
+    if (starts_in.back() == 1) {
+      offset = x.numel() / 2;
+    }
+    // int copy(Context* ctx, const T* x, T* y, int64_t len)
+    r = xpu::copy<XPUType>(dev_ctx.x_context(),
+                           x_transpose + offset,
+                           reinterpret_cast<XPUType*>(out->data<T>()),
+                           x.numel() / 2);
+    PADDLE_ENFORCE_XDNN_SUCCESS(r, "copy");
+    return;
+  }
+
   int r = xpu::strided_slice(dev_ctx.x_context(),
                              reinterpret_cast<const XPUType*>(x.data<T>()),
                              reinterpret_cast<XPUType*>(out->data<T>()),

paddle/phi/kernels/xpu/stride_slice_util.h

@@ -0,0 +1,54 @@
+// Copyright (c) 2023 PaddlePaddle Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include <vector>
+
+namespace phi {
+
+inline bool is_strided_slice_special_case(const std::vector<int>& xshape,
+                                          const std::vector<int>& starts,
+                                          const std::vector<int>& ends,
+                                          const std::vector<int>& strides) {
+  // starts match {0, 0, ..., 0, 0} or {0, 0, ..., 0, 1}
+  for (size_t i = 0; i < starts.size() - 1; i++) {
+    if (starts[i] != 0) {
+      return false;
+    }
+  }
+  if (starts.back() != 0 && starts.back() != 1) {
+    return false;
+  }
+  // xshape match ends
+  if (xshape != ends) {
+    return false;
+  }
+  // strides match {1, 1, ..., 1, 2}
+  for (size_t i = 0; i < strides.size() - 1; i++) {
+    if (strides[i] != 1) {
+      return false;
+    }
+  }
+  if (strides.back() != 2) {
+    return false;
+  }
+  // last dim of xshape is even number
+  if (xshape.back() % 2 != 0) {
+    return false;
+  }
+  return true;
+}
+
+}  // namespace phi

test/xpu/test_strided_slice_op_xpu.py

@@ -174,6 +174,24 @@ def initTestCase(self):
             self.strides = [1, 1, 1, 1, 1, 2]
             self.infer_flags = [1, 1, 1, 1, 1]
 
+    class XPUTestStrideSliceOp_eb_1(XPUTestStrideSliceOp):
+        def initTestCase(self):
+            self.inshape = (1, 4, 4096, 128)
+            self.axes = [0, 1, 2, 3]
+            self.starts = [0, 0, 0, 0]
+            self.ends = [1, 4, 4096, 128]
+            self.strides = [1, 1, 1, 2]
+            self.infer_flags = [1, 1, 1, 1]
+
+    class XPUTestStrideSliceOp_eb_2(XPUTestStrideSliceOp):
+        def initTestCase(self):
+            self.inshape = (1, 4, 4096, 128)
+            self.axes = [0, 1, 2, 3]
+            self.starts = [0, 0, 0, 1]
+            self.ends = [1, 4, 4096, 128]
+            self.strides = [1, 1, 1, 2]
+            self.infer_flags = [1, 1, 1, 1]
+
 
 support_types = get_xpu_op_support_types('strided_slice')
 for stype in support_types: