enable SSE2 in skia/convolver for linux32

skia/ext/convolver_SSE2.cc

Index: skia/ext/convolver_SSE2.cc
diff --git a/skia/ext/convolver.cc b/skia/ext/convolver_SSE2.cc
similarity index 51%
copy from skia/ext/convolver.cc
copy to skia/ext/convolver_SSE2.cc
index 47e3711fac4883c361e880b9cfce9241d52410c2..a823edcb519291d89ed79c448efa98f9569bb788 100644
--- a/skia/ext/convolver.cc
+++ b/skia/ext/convolver_SSE2.cc
@@ -5,231 +5,18 @@
 #include <algorithm>
 
 #include "skia/ext/convolver.h"
+#include "skia/ext/convolver_SSE2.h"
 #include "third_party/skia/include/core/SkTypes.h"
 
-#if defined(SIMD_SSE2)
 #include <emmintrin.h>  // ARCH_CPU_X86_FAMILY was defined in build/config.h
-#endif
 
 namespace skia {
 
-namespace {
-
-// Converts the argument to an 8-bit unsigned value by clamping to the range
-// 0-255.
-inline unsigned char ClampTo8(int a) {
-  if (static_cast<unsigned>(a) < 256)
-    return a;  // Avoid the extra check in the common case.
-  if (a < 0)
-    return 0;
-  return 255;
-}
-
-// Stores a list of rows in a circular buffer. The usage is you write into it
-// by calling AdvanceRow. It will keep track of which row in the buffer it
-// should use next, and the total number of rows added.
-class CircularRowBuffer {
- public:
-  // The number of pixels in each row is given in |source_row_pixel_width|.
-  // The maximum number of rows needed in the buffer is |max_y_filter_size|
-  // (we only need to store enough rows for the biggest filter).
-  //
-  // We use the |first_input_row| to compute the coordinates of all of the
-  // following rows returned by Advance().
-  CircularRowBuffer(int dest_row_pixel_width, int max_y_filter_size,
-                    int first_input_row)
-      : row_byte_width_(dest_row_pixel_width * 4),
-        num_rows_(max_y_filter_size),
-        next_row_(0),
-        next_row_coordinate_(first_input_row) {
-    buffer_.resize(row_byte_width_ * max_y_filter_size);
-    row_addresses_.resize(num_rows_);
-  }
-
-  // Moves to the next row in the buffer, returning a pointer to the beginning
-  // of it.
-  unsigned char* AdvanceRow() {
-    unsigned char* row = &buffer_[next_row_ * row_byte_width_];
-    next_row_coordinate_++;
-
-    // Set the pointer to the next row to use, wrapping around if necessary.
-    next_row_++;
-    if (next_row_ == num_rows_)
-      next_row_ = 0;
-    return row;
-  }
-
-  // Returns a pointer to an "unrolled" array of rows. These rows will start
-  // at the y coordinate placed into |*first_row_index| and will continue in
-  // order for the maximum number of rows in this circular buffer.
-  //
-  // The |first_row_index_| may be negative. This means the circular buffer
-  // starts before the top of the image (it hasn't been filled yet).
-  unsigned char* const* GetRowAddresses(int* first_row_index) {
-    // Example for a 4-element circular buffer holding coords 6-9.
-    //   Row 0   Coord 8
-    //   Row 1   Coord 9
-    //   Row 2   Coord 6  <- next_row_ = 2, next_row_coordinate_ = 10.
-    //   Row 3   Coord 7
-    //
-    // The "next" row is also the first (lowest) coordinate. This computation
-    // may yield a negative value, but that's OK, the math will work out
-    // since the user of this buffer will compute the offset relative
-    // to the first_row_index and the negative rows will never be used.
-    *first_row_index = next_row_coordinate_ - num_rows_;
-
-    int cur_row = next_row_;
-    for (int i = 0; i < num_rows_; i++) {
-      row_addresses_[i] = &buffer_[cur_row * row_byte_width_];
-
-      // Advance to the next row, wrapping if necessary.
-      cur_row++;
-      if (cur_row == num_rows_)
-        cur_row = 0;
-    }
-    return &row_addresses_[0];
-  }
-
- private:
-  // The buffer storing the rows. They are packed, each one row_byte_width_.
-  std::vector<unsigned char> buffer_;
-
-  // Number of bytes per row in the |buffer_|.
-  int row_byte_width_;
-
-  // The number of rows available in the buffer.
-  int num_rows_;
-
-  // The next row index we should write into. This wraps around as the
-  // circular buffer is used.
-  int next_row_;
-
-  // The y coordinate of the |next_row_|. This is incremented each time a
-  // new row is appended and does not wrap.
-  int next_row_coordinate_;
-
-  // Buffer used by GetRowAddresses().
-  std::vector<unsigned char*> row_addresses_;
-};
-
-// Convolves horizontally along a single row. The row data is given in
-// |src_data| and continues for the num_values() of the filter.
-template<bool has_alpha>
-void ConvolveHorizontally(const unsigned char* src_data,
-                          const ConvolutionFilter1D& filter,
-                          unsigned char* out_row) {
-  // Loop over each pixel on this row in the output image.
-  int num_values = filter.num_values();
-  for (int out_x = 0; out_x < num_values; out_x++) {
-    // Get the filter that determines the current output pixel.
-    int filter_offset, filter_length;
-    const ConvolutionFilter1D::Fixed* filter_values =
-        filter.FilterForValue(out_x, &filter_offset, &filter_length);
-
-    // Compute the first pixel in this row that the filter affects. It will
-    // touch |filter_length| pixels (4 bytes each) after this.
-    const unsigned char* row_to_filter = &src_data[filter_offset * 4];
-
-    // Apply the filter to the row to get the destination pixel in |accum|.
-    int accum[4] = {0};
-    for (int filter_x = 0; filter_x < filter_length; filter_x++) {
-      ConvolutionFilter1D::Fixed cur_filter = filter_values[filter_x];
-      accum[0] += cur_filter * row_to_filter[filter_x * 4 + 0];
-      accum[1] += cur_filter * row_to_filter[filter_x * 4 + 1];
-      accum[2] += cur_filter * row_to_filter[filter_x * 4 + 2];
-      if (has_alpha)
-        accum[3] += cur_filter * row_to_filter[filter_x * 4 + 3];
-    }
-
-    // Bring this value back in range. All of the filter scaling factors
-    // are in fixed point with kShiftBits bits of fractional part.
-    accum[0] >>= ConvolutionFilter1D::kShiftBits;
-    accum[1] >>= ConvolutionFilter1D::kShiftBits;
-    accum[2] >>= ConvolutionFilter1D::kShiftBits;
-    if (has_alpha)
-      accum[3] >>= ConvolutionFilter1D::kShiftBits;
-
-    // Store the new pixel.
-    out_row[out_x * 4 + 0] = ClampTo8(accum[0]);
-    out_row[out_x * 4 + 1] = ClampTo8(accum[1]);
-    out_row[out_x * 4 + 2] = ClampTo8(accum[2]);
-    if (has_alpha)
-      out_row[out_x * 4 + 3] = ClampTo8(accum[3]);
-  }
-}
-
-// Does vertical convolution to produce one output row. The filter values and
-// length are given in the first two parameters. These are applied to each
-// of the rows pointed to in the |source_data_rows| array, with each row
-// being |pixel_width| wide.
-//
-// The output must have room for |pixel_width * 4| bytes.
-template<bool has_alpha>
-void ConvolveVertically(const ConvolutionFilter1D::Fixed* filter_values,
-                        int filter_length,
-                        unsigned char* const* source_data_rows,
-                        int pixel_width,
-                        unsigned char* out_row) {
-  // We go through each column in the output and do a vertical convolution,
-  // generating one output pixel each time.
-  for (int out_x = 0; out_x < pixel_width; out_x++) {
-    // Compute the number of bytes over in each row that the current column
-    // we're convolving starts at. The pixel will cover the next 4 bytes.
-    int byte_offset = out_x * 4;
-
-    // Apply the filter to one column of pixels.
-    int accum[4] = {0};
-    for (int filter_y = 0; filter_y < filter_length; filter_y++) {
-      ConvolutionFilter1D::Fixed cur_filter = filter_values[filter_y];
-      accum[0] += cur_filter * source_data_rows[filter_y][byte_offset + 0];
-      accum[1] += cur_filter * source_data_rows[filter_y][byte_offset + 1];
-      accum[2] += cur_filter * source_data_rows[filter_y][byte_offset + 2];
-      if (has_alpha)
-        accum[3] += cur_filter * source_data_rows[filter_y][byte_offset + 3];
-    }
-
-    // Bring this value back in range. All of the filter scaling factors
-    // are in fixed point with kShiftBits bits of precision.
-    accum[0] >>= ConvolutionFilter1D::kShiftBits;
-    accum[1] >>= ConvolutionFilter1D::kShiftBits;
-    accum[2] >>= ConvolutionFilter1D::kShiftBits;
-    if (has_alpha)
-      accum[3] >>= ConvolutionFilter1D::kShiftBits;
-
-    // Store the new pixel.
-    out_row[byte_offset + 0] = ClampTo8(accum[0]);
-    out_row[byte_offset + 1] = ClampTo8(accum[1]);
-    out_row[byte_offset + 2] = ClampTo8(accum[2]);
-    if (has_alpha) {
-      unsigned char alpha = ClampTo8(accum[3]);
-
-      // Make sure the alpha channel doesn't come out smaller than any of the
-      // color channels. We use premultipled alpha channels, so this should
-      // never happen, but rounding errors will cause this from time to time.
-      // These "impossible" colors will cause overflows (and hence random pixel
-      // values) when the resulting bitmap is drawn to the screen.
-      //
-      // We only need to do this when generating the final output row (here).
-      int max_color_channel = std::max(out_row[byte_offset + 0],
-          std::max(out_row[byte_offset + 1], out_row[byte_offset + 2]));
-      if (alpha < max_color_channel)
-        out_row[byte_offset + 3] = max_color_channel;
-      else
-        out_row[byte_offset + 3] = alpha;
-    } else {
-      // No alpha channel, the image is opaque.
-      out_row[byte_offset + 3] = 0xff;
-    }
-  }
-}
-
-
 // Convolves horizontally along a single row. The row data is given in
 // |src_data| and continues for the num_values() of the filter.
 void ConvolveHorizontally_SSE2(const unsigned char* src_data,
                                const ConvolutionFilter1D& filter,
                                unsigned char* out_row) {
-#if defined(SIMD_SSE2)
   int num_values = filter.num_values();
 
   int filter_offset, filter_length;
@@ -350,17 +137,15 @@ void ConvolveHorizontally_SSE2(const unsigned char* src_data,
     *(reinterpret_cast<int*>(out_row)) = _mm_cvtsi128_si32(accum);
     out_row += 4;
   }
-#endif
 }
 
 // Convolves horizontally along four rows. The row data is given in
 // |src_data| and continues for the num_values() of the filter.
 // The algorithm is almost same as |ConvolveHorizontally_SSE2|. Please
 // refer to that function for detailed comments.
-void ConvolveHorizontally4_SSE2(const unsigned char* src_data[4],
-                                const ConvolutionFilter1D& filter,
-                                unsigned char* out_row[4]) {
-#if defined(SIMD_SSE2)
+void Convolve4RowsHorizontally_SSE2(const unsigned char* src_data[4],
+                                    const ConvolutionFilter1D& filter,
+                                    unsigned char* out_row[4]) {
   int num_values = filter.num_values();
 
   int filter_offset, filter_length;
@@ -471,7 +256,6 @@ void ConvolveHorizontally4_SSE2(const unsigned char* src_data[4],
     out_row[2] += 4;
     out_row[3] += 4;
   }
-#endif
 }
 
 // Does vertical convolution to produce one output row. The filter values and
@@ -486,7 +270,6 @@ void ConvolveVertically_SSE2(const ConvolutionFilter1D::Fixed* filter_values,
                              unsigned char* const* source_data_rows,
                              int pixel_width,
                              unsigned char* out_row) {
-#if defined(SIMD_SSE2)
   int width = pixel_width & ~3;
 
   __m128i zero = _mm_setzero_si128();
@@ -647,226 +430,26 @@ void ConvolveVertically_SSE2(const ConvolutionFilter1D::Fixed* filter_values,
       out_row += 4;
     }
   }
-#endif
 }
 
-}  // namespace
-
-// ConvolutionFilter1D ---------------------------------------------------------
-
-ConvolutionFilter1D::ConvolutionFilter1D()
-    : max_filter_(0) {
-}
-
-ConvolutionFilter1D::~ConvolutionFilter1D() {
-}
-
-void ConvolutionFilter1D::AddFilter(int filter_offset,
-                                    const float* filter_values,
-                                    int filter_length) {
-  SkASSERT(filter_length > 0);
-
-  std::vector<Fixed> fixed_values;
-  fixed_values.reserve(filter_length);
-
-  for (int i = 0; i < filter_length; ++i)
-    fixed_values.push_back(FloatToFixed(filter_values[i]));
-
-  AddFilter(filter_offset, &fixed_values[0], filter_length);
-}
-
-void ConvolutionFilter1D::AddFilter(int filter_offset,
-                                    const Fixed* filter_values,
-                                    int filter_length) {
-  // It is common for leading/trailing filter values to be zeros. In such
-  // cases it is beneficial to only store the central factors.
-  // For a scaling to 1/4th in each dimension using a Lanczos-2 filter on
-  // a 1080p image this optimization gives a ~10% speed improvement.
-  int first_non_zero = 0;
-  while (first_non_zero < filter_length && filter_values[first_non_zero] == 0)
-    first_non_zero++;
-
-  if (first_non_zero < filter_length) {
-    // Here we have at least one non-zero factor.
-    int last_non_zero = filter_length - 1;
-    while (last_non_zero >= 0 && filter_values[last_non_zero] == 0)
-      last_non_zero--;
-
-    filter_offset += first_non_zero;
-    filter_length = last_non_zero + 1 - first_non_zero;
-    SkASSERT(filter_length > 0);
-
-    for (int i = first_non_zero; i <= last_non_zero; i++)
-      filter_values_.push_back(filter_values[i]);
+void ConvolveVertically_SSE2(const ConvolutionFilter1D::Fixed* filter_values,

[Stephen White, 2013/04/05 08:40:47]

It might be a good idea to add a similar wrapper for the non-SSE2 flavour as
well.  It would clean up the call site a bit to hide the template parameters in
the same way, as well as making it more symmetrical with the SSE2 path.

[hubbe, 2013/04/06 20:45:46]

Done.

+                             int filter_length,
+                             unsigned char* const* source_data_rows,
+                             int pixel_width,
+                             unsigned char* out_row,
+                             bool has_alpha) {
+  if (has_alpha) {
+    ConvolveVertically_SSE2<true>(filter_values,
+                                  filter_length,
+                                  source_data_rows,
+                                  pixel_width,
+                                  out_row);
   } else {
-    // Here all the factors were zeroes.
-    filter_length = 0;
-  }
-
-  FilterInstance instance;
-
-  // We pushed filter_length elements onto filter_values_
-  instance.data_location = (static_cast<int>(filter_values_.size()) -
-                            filter_length);
-  instance.offset = filter_offset;
-  instance.length = filter_length;
-  filters_.push_back(instance);
-
-  max_filter_ = std::max(max_filter_, filter_length);
-}
-
-void BGRAConvolve2D(const unsigned char* source_data,
-                    int source_byte_row_stride,
-                    bool source_has_alpha,
-                    const ConvolutionFilter1D& filter_x,
-                    const ConvolutionFilter1D& filter_y,
-                    int output_byte_row_stride,
-                    unsigned char* output,
-                    bool use_sse2) {
-#if !defined(SIMD_SSE2)
-  // Even we have runtime support for SSE2 instructions, since the binary
-  // was not built with SSE2 support, we had to fallback to C version.
-  use_sse2 = false;
-#endif
-
-  int max_y_filter_size = filter_y.max_filter();
-
-  // The next row in the input that we will generate a horizontally
-  // convolved row for. If the filter doesn't start at the beginning of the
-  // image (this is the case when we are only resizing a subset), then we
-  // don't want to generate any output rows before that. Compute the starting
-  // row for convolution as the first pixel for the first vertical filter.
-  int filter_offset, filter_length;
-  const ConvolutionFilter1D::Fixed* filter_values =
-      filter_y.FilterForValue(0, &filter_offset, &filter_length);
-  int next_x_row = filter_offset;
-
-  // We loop over each row in the input doing a horizontal convolution. This
-  // will result in a horizontally convolved image. We write the results into
-  // a circular buffer of convolved rows and do vertical convolution as rows
-  // are available. This prevents us from having to store the entire
-  // intermediate image and helps cache coherency.
-  // We will need four extra rows to allow horizontal convolution could be done
-  // simultaneously. We also padding each row in row buffer to be aligned-up to
-  // 16 bytes.
-  // TODO(jiesun): We do not use aligned load from row buffer in vertical
-  // convolution pass yet. Somehow Windows does not like it.
-  int row_buffer_width = (filter_x.num_values() + 15) & ~0xF;
-  int row_buffer_height = max_y_filter_size + (use_sse2 ? 4 : 0);
-  CircularRowBuffer row_buffer(row_buffer_width,
-                               row_buffer_height,
-                               filter_offset);
-
-  // Loop over every possible output row, processing just enough horizontal
-  // convolutions to run each subsequent vertical convolution.
-  SkASSERT(output_byte_row_stride >= filter_x.num_values() * 4);
-  int num_output_rows = filter_y.num_values();
-
-  // We need to check which is the last line to convolve before we advance 4
-  // lines in one iteration.
-  int last_filter_offset, last_filter_length;
-
-  // SSE2 can access up to 3 extra pixels past the end of the
-  // buffer. At the bottom of the image, we have to be careful
-  // not to access data past the end of the buffer. Normally
-  // we fall back to the C++ implementation for the last row.
-  // If the last row is less than 3 pixels wide, we may have to fall
-  // back to the C++ version for more rows. Compute how many
-  // rows we need to avoid the SSE implementation for here.
-  filter_x.FilterForValue(filter_x.num_values() - 1, &last_filter_offset,
-                          &last_filter_length);
-  int avoid_sse_rows = 1 + 3/(last_filter_offset + last_filter_length);
-
-  filter_y.FilterForValue(num_output_rows - 1, &last_filter_offset,
-                          &last_filter_length);
-
-  for (int out_y = 0; out_y < num_output_rows; out_y++) {
-    filter_values = filter_y.FilterForValue(out_y,
-                                            &filter_offset, &filter_length);
-
-    // Generate output rows until we have enough to run the current filter.
-    if (use_sse2) {
-      while (next_x_row < filter_offset + filter_length) {
-        if (next_x_row + 3 < last_filter_offset + last_filter_length -
-            avoid_sse_rows) {
-          const unsigned char* src[4];
-          unsigned char* out_row[4];
-          for (int i = 0; i < 4; ++i) {
-            src[i] = &source_data[(next_x_row + i) * source_byte_row_stride];
-            out_row[i] = row_buffer.AdvanceRow();
-          }
-          ConvolveHorizontally4_SSE2(src, filter_x, out_row);
-          next_x_row += 4;
-        } else {
-          // Check if we need to avoid SSE2 for this row.
-          if (next_x_row >= last_filter_offset + last_filter_length -
-              avoid_sse_rows) {
-            if (source_has_alpha) {
-              ConvolveHorizontally<true>(
-                  &source_data[next_x_row * source_byte_row_stride],
-                  filter_x, row_buffer.AdvanceRow());
-            } else {
-              ConvolveHorizontally<false>(
-                  &source_data[next_x_row * source_byte_row_stride],
-                  filter_x, row_buffer.AdvanceRow());
-            }
-          } else {
-            ConvolveHorizontally_SSE2(
-                &source_data[next_x_row * source_byte_row_stride],
-                filter_x, row_buffer.AdvanceRow());
-          }
-          next_x_row++;
-        }
-      }
-    } else {
-      while (next_x_row < filter_offset + filter_length) {
-        if (source_has_alpha) {
-          ConvolveHorizontally<true>(
-              &source_data[next_x_row * source_byte_row_stride],
-              filter_x, row_buffer.AdvanceRow());
-        } else {
-          ConvolveHorizontally<false>(
-              &source_data[next_x_row * source_byte_row_stride],
-              filter_x, row_buffer.AdvanceRow());
-        }
-        next_x_row++;
-      }
-    }
-
-    // Compute where in the output image this row of final data will go.
-    unsigned char* cur_output_row = &output[out_y * output_byte_row_stride];
-
-    // Get the list of rows that the circular buffer has, in order.
-    int first_row_in_circular_buffer;
-    unsigned char* const* rows_to_convolve =
-        row_buffer.GetRowAddresses(&first_row_in_circular_buffer);
-
-    // Now compute the start of the subset of those rows that the filter
-    // needs.
-    unsigned char* const* first_row_for_filter =
-        &rows_to_convolve[filter_offset - first_row_in_circular_buffer];
-
-    if (source_has_alpha) {
-      if (use_sse2) {
-        ConvolveVertically_SSE2<true>(filter_values, filter_length,
-                                      first_row_for_filter,
-                                      filter_x.num_values(), cur_output_row);
-      } else {
-        ConvolveVertically<true>(filter_values, filter_length,
-                                 first_row_for_filter,
-                                 filter_x.num_values(), cur_output_row);
-      }
-    } else {
-      if (use_sse2) {
-        ConvolveVertically_SSE2<false>(filter_values, filter_length,
-                                       first_row_for_filter,
-                                       filter_x.num_values(), cur_output_row);
-      } else {
-        ConvolveVertically<false>(filter_values, filter_length,
-                                 first_row_for_filter,
-                                 filter_x.num_values(), cur_output_row);
-      }
-    }
+    ConvolveVertically_SSE2<false>(filter_values,
+                                   filter_length,
+                                   source_data_rows,
+                                   pixel_width,
+                                   out_row);
   }
 }