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Remove excessive floating-point divides #4312

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Remove excessive floating-point divides #4312

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41faf69
Remove excessive floating-point divides
heshpdx Sep 3, 2024
7ab67f9
Apply suggestions from code review
heshpdx Sep 3, 2024
ff0a38d
Fix function definition and comment to match cpp file
heshpdx Sep 3, 2024
7852c79
Replace FDIV with FMUL in hot loop.
heshpdx Sep 23, 2024
a2a85b1
Update src/lstm/functions.h
heshpdx Sep 23, 2024
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3 changes: 2 additions & 1 deletion src/lstm/functions.h
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Original file line number Diff line number Diff line change
Expand Up @@ -200,8 +200,9 @@ inline void SoftmaxInPlace(int n, T *inout) {
inout[i] = prob;
}
if (prob_total > 0) {
T inv_prob_total = 1 / prob_total;
for (int i = 0; i < n; i++) {
inout[i] /= prob_total;
inout[i] *= inv_prob_total;
Comment on lines +203 to +205
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Isn't this kind of optimization something which a good compiler should do automatically?

}
}
}
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13 changes: 8 additions & 5 deletions src/lstm/networkio.cpp
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Expand Up @@ -224,6 +224,7 @@ void NetworkIO::Copy2DImage(int batch, Image pix, float black, float contrast, T
int target_width = stride_map_.Size(FD_WIDTH);
int num_features = NumFeatures();
bool color = num_features == 3;
float inv_contrast = 1 / contrast;
if (width > target_width) {
width = target_width;
}
Expand All @@ -236,11 +237,11 @@ void NetworkIO::Copy2DImage(int batch, Image pix, float black, float contrast, T
int f = 0;
for (int c = COLOR_RED; c <= COLOR_BLUE; ++c) {
int pixel = GET_DATA_BYTE(line + x, c);
SetPixel(t, f++, pixel, black, contrast);
SetPixel(t, f++, pixel, black, inv_contrast);
}
} else {
int pixel = GET_DATA_BYTE(line, x);
SetPixel(t, 0, pixel, black, contrast);
SetPixel(t, 0, pixel, black, inv_contrast);
}
}
}
Expand All @@ -264,6 +265,7 @@ void NetworkIO::Copy1DGreyImage(int batch, Image pix, float black, float contras
index.AddOffset(batch, FD_BATCH);
int t = index.t();
int target_width = stride_map_.Size(FD_WIDTH);
float inv_contrast = 1 / contrast;
if (width > target_width) {
width = target_width;
}
Expand All @@ -272,7 +274,7 @@ void NetworkIO::Copy1DGreyImage(int batch, Image pix, float black, float contras
for (int y = 0; y < height; ++y) {
uint32_t *line = pixGetData(pix) + wpl * y;
int pixel = GET_DATA_BYTE(line, x);
SetPixel(t, y, pixel, black, contrast);
SetPixel(t, y, pixel, black, inv_contrast);
}
}
for (; x < target_width; ++x) {
Expand All @@ -287,8 +289,9 @@ void NetworkIO::Copy1DGreyImage(int batch, Image pix, float black, float contras
// pixel: the value of the pixel from the image (in one channel)
// black: the pixel value to map to the lowest of the range of *this
// contrast: the range of pixel values to stretch to half the range of *this.
void NetworkIO::SetPixel(int t, int f, int pixel, float black, float contrast) {
float float_pixel = (pixel - black) / contrast - 1.0f;
// inv_contrast: one over the contrast, to save a divide
void NetworkIO::SetPixel(int t, int f, int pixel, float black, float inv_contrast) {
float float_pixel = (pixel - black) * inv_contrast - 1.0f;
if (int_mode_) {
i_[t][f] = ClipToRange<int>(IntCastRounded((INT8_MAX + 1) * float_pixel), -INT8_MAX, INT8_MAX);
} else {
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3 changes: 2 additions & 1 deletion src/lstm/networkio.h
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Expand Up @@ -92,7 +92,8 @@ class TESS_API NetworkIO {
// pixel: the value of the pixel from the image (in one channel)
// black: the pixel value to map to the lowest of the range of *this
// contrast: the range of pixel values to stretch to half the range of *this.
void SetPixel(int t, int f, int pixel, float black, float contrast);
// inv_contrast: one over the contrast, to save a divide
void SetPixel(int t, int f, int pixel, float black, float inv_contrast);
// Converts the array to a Pix. Must be pixDestroyed after use.
Image ToPix() const;
// Prints the first and last num timesteps of the array for each feature.
Expand Down
9 changes: 6 additions & 3 deletions src/textord/pithsync.cpp
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Expand Up @@ -120,6 +120,7 @@ void FPCUTPT::assign( // constructor
// half of pitch
int16_t half_pitch = pitch / 2 - 1;
uint32_t lead_flag; // new flag
float inv_projection_scale = 1 / projection_scale;

if (half_pitch > 31) {
half_pitch = 31;
Expand Down Expand Up @@ -166,7 +167,7 @@ void FPCUTPT::assign( // constructor
}
}
balance_count =
static_cast<int16_t>(balance_count * textord_balance_factor / projection_scale);
static_cast<int16_t>(balance_count * textord_balance_factor * inv_projection_scale);
}
r_index = segpt->region_index + 1;
total = segpt->mean_sum + dist;
Expand Down Expand Up @@ -221,6 +222,7 @@ void FPCUTPT::assign_cheap( // constructor
// half of pitch
int16_t half_pitch = pitch / 2 - 1;
uint32_t lead_flag; // new flag
float inv_projection_scale = 1 / projection_scale;

if (half_pitch > 31) {
half_pitch = 31;
Expand Down Expand Up @@ -260,7 +262,7 @@ void FPCUTPT::assign_cheap( // constructor
lead_flag &= lead_flag - 1;
}
balance_count =
static_cast<int16_t>(balance_count * textord_balance_factor / projection_scale);
static_cast<int16_t>(balance_count * textord_balance_factor * inv_projection_scale);
}
r_index = segpt->region_index + 1;
total = segpt->mean_sum + dist;
Expand Down Expand Up @@ -511,6 +513,7 @@ double check_pitch_sync3( // find segmentation
int16_t best_fake; // best fake level
int16_t best_count; // no of cuts
FPSEGPT_IT seg_it = seg_list; // output iterator
float inv_projection_scale = 1 / projection_scale;

end = (end - start) % pitch;
if (pitch < 3) {
Expand Down Expand Up @@ -597,7 +600,7 @@ double check_pitch_sync3( // find segmentation
offset = projection->pile_count(x);
faking = true;
} else {
projection_offset = static_cast<int16_t>(projection->pile_count(x) / projection_scale);
projection_offset = static_cast<int16_t>(projection->pile_count(x) * inv_projection_scale);
if (projection_offset > offset) {
offset = projection_offset;
}
Expand Down
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