stretch engine: Hoist a options reads out of loops
clang can't easily prove that these reads are loop-invariant since they
depend on the load of a member variable. Help the compiler out.
(Found by jroelofs.)
Bug: none
Change-Id: I2ef810ab57bc98b19839faae1d05cdd9cba5f0a1
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/74590
Commit-Queue: Nico Weber <thakis@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxge/dib/cstretchengine.cpp b/core/fxge/dib/cstretchengine.cpp
index f794261..e36c418 100644
--- a/core/fxge/dib/cstretchengine.cpp
+++ b/core/fxge/dib/cstretchengine.cpp
@@ -41,11 +41,15 @@
int src_min,
int src_max,
const FXDIB_ResampleOptions& options) {
+ // Help the compiler realize that these can't change during a loop iteration:
+ const bool bilinear = options.bInterpolateBilinear;
+ const bool bicubic = options.bInterpolateBicubic;
+
m_WeightTables.clear();
m_dwWeightTablesSize = 0;
const double scale = static_cast<float>(src_len) / dest_len;
const double base = dest_len < 0 ? src_len : 0;
- const int ext_size = options.bInterpolateBicubic ? 3 : 1;
+ const int ext_size = bicubic ? 3 : 1;
m_ItemSize =
sizeof(int) * 2 +
static_cast<int>(sizeof(int) *
@@ -61,7 +65,7 @@
for (int dest_pixel = dest_min; dest_pixel < dest_max; ++dest_pixel) {
PixelWeight& pixel_weights = *GetPixelWeight(dest_pixel);
double src_pos = dest_pixel * scale + scale / 2 + base;
- if (options.bInterpolateBilinear) {
+ if (bilinear) {
pixel_weights.m_SrcStart =
static_cast<int>(floor(static_cast<float>(src_pos) - 1.0f / 2));
pixel_weights.m_SrcEnd =
@@ -77,7 +81,7 @@
65536);
pixel_weights.m_Weights[0] = 65536 - pixel_weights.m_Weights[1];
}
- } else if (options.bInterpolateBicubic) {
+ } else if (bicubic) {
pixel_weights.m_SrcStart =
static_cast<int>(floor(static_cast<float>(src_pos) - 1.0f / 2));
pixel_weights.m_SrcEnd =
@@ -350,6 +354,9 @@
if (m_pSource->SkipToScanline(m_CurRow, pPause))
return true;
+ // Help the compiler realize that this can't change during a loop iteration:
+ const bool bicubic = m_ResampleOptions.bInterpolateBicubic;
+
int Bpp = m_DestBpp / 8;
static const int kStrechPauseRows = 10;
int rows_to_go = kStrechPauseRows;
@@ -387,7 +394,7 @@
if (src_scan[j / 8] & (1 << (7 - j % 8)))
dest_a += pixel_weight * 255;
}
- if (m_ResampleOptions.bInterpolateBicubic)
+ if (bicubic)
dest_a = pdfium::clamp(dest_a, 0, kMaxDestValue);
*dest_scan++ = static_cast<uint8_t>(dest_a >> 16);
}
@@ -405,7 +412,7 @@
int pixel_weight = *pWeight;
dest_a += pixel_weight * src_scan[j];
}
- if (m_ResampleOptions.bInterpolateBicubic)
+ if (bicubic)
dest_a = pdfium::clamp(dest_a, 0, kMaxDestValue);
*dest_scan++ = static_cast<uint8_t>(dest_a >> 16);
}
@@ -426,7 +433,7 @@
dest_r += pixel_weight * src_scan[j];
dest_a += pixel_weight;
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_r = pdfium::clamp(dest_r, 0, kMaxDestValue);
dest_a = pdfium::clamp(dest_a, 0, 65536);
}
@@ -458,7 +465,7 @@
dest_r_y += pixel_weight * static_cast<uint8_t>(argb_cmyk >> 8);
}
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_r_y = pdfium::clamp(dest_r_y, 0, kMaxDestValue);
dest_g_m = pdfium::clamp(dest_g_m, 0, kMaxDestValue);
dest_b_c = pdfium::clamp(dest_b_c, 0, kMaxDestValue);
@@ -495,7 +502,7 @@
}
dest_a += pixel_weight;
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_b_c = pdfium::clamp(dest_b_c, 0, kMaxDestValue);
dest_g_m = pdfium::clamp(dest_g_m, 0, kMaxDestValue);
dest_r_y = pdfium::clamp(dest_r_y, 0, kMaxDestValue);
@@ -525,7 +532,7 @@
dest_g_m += pixel_weight * (*src_pixel++);
dest_r_y += pixel_weight * (*src_pixel);
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_b_c = pdfium::clamp(dest_b_c, 0, kMaxDestValue);
dest_g_m = pdfium::clamp(dest_g_m, 0, kMaxDestValue);
dest_r_y = pdfium::clamp(dest_r_y, 0, kMaxDestValue);
@@ -561,7 +568,7 @@
dest_r_y += pixel_weight * (*src_pixel);
dest_a += pixel_weight;
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_r_y = pdfium::clamp(dest_r_y, 0, kMaxDestValue);
dest_g_m = pdfium::clamp(dest_g_m, 0, kMaxDestValue);
dest_b_c = pdfium::clamp(dest_b_c, 0, kMaxDestValue);
@@ -595,6 +602,9 @@
if (!ret)
return;
+ // Help the compiler realize that this can't change during a loop iteration:
+ const bool bicubic = m_ResampleOptions.bInterpolateBicubic;
+
const int DestBpp = m_DestBpp / 8;
for (int row = m_DestClip.top; row < m_DestClip.bottom; ++row) {
unsigned char* dest_scan = m_DestScanline.data();
@@ -617,7 +627,7 @@
dest_a +=
pixel_weight * src_scan[(j - m_SrcClip.top) * m_InterPitch];
}
- if (m_ResampleOptions.bInterpolateBicubic)
+ if (bicubic)
dest_a = pdfium::clamp(dest_a, 0, kMaxDestValue);
*dest_scan = static_cast<uint8_t>(dest_a >> 16);
dest_scan += DestBpp;
@@ -643,7 +653,7 @@
dest_a += pixel_weight *
src_scan_mask[(j - m_SrcClip.top) * m_ExtraMaskPitch];
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_k = pdfium::clamp(dest_k, 0, kMaxDestValue);
dest_a = pdfium::clamp(dest_a, 0, kMaxDestValue);
}
@@ -673,7 +683,7 @@
dest_g_m += pixel_weight * (*src_pixel++);
dest_r_y += pixel_weight * (*src_pixel);
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_r_y = pdfium::clamp(dest_r_y, 0, kMaxDestValue);
dest_g_m = pdfium::clamp(dest_g_m, 0, kMaxDestValue);
dest_b_c = pdfium::clamp(dest_b_c, 0, kMaxDestValue);
@@ -716,7 +726,7 @@
else
dest_a += pixel_weight * mask_v;
}
- if (m_ResampleOptions.bInterpolateBicubic) {
+ if (bicubic) {
dest_r_y = pdfium::clamp(dest_r_y, 0, kMaxDestValue);
dest_g_m = pdfium::clamp(dest_g_m, 0, kMaxDestValue);
dest_b_c = pdfium::clamp(dest_b_c, 0, kMaxDestValue);
