MozillaThunderbird/mozilla-bmo1504834-part2.patch

# HG changeset patch
# Parent  0e579dcbf7328dda4512cbdafc9b42acec4935ea
Skia does not support big endian. The places to fix are too numerous and upstream (skia, not Mozilla)
has no interest in maintaining big endian.
So here we try to swizzle the input for skia, so that skia always works on LE, and when it comes
out again, we transform back to BE.

diff -r 0e579dcbf732 gfx/2d/ConvolutionFilter.cpp
--- a/gfx/2d/ConvolutionFilter.cpp	Wed Jan 08 12:17:44 2020 +0100
+++ b/gfx/2d/ConvolutionFilter.cpp	Wed Jan 08 12:17:49 2020 +0100
@@ -35,9 +35,38 @@
   return true;
 }
 
+static void ByteSwapArray(uint8_t *u8Array, int32_t size) {
+    uint32_t *array = reinterpret_cast<uint32_t*>(u8Array);
+    for (int pxl = 0; pxl < size; ++pxl) {
+        // Use an endian swap to move the bytes, i.e. BGRA -> ARGB.
+        uint32_t rgba = array[pxl];
+        array[pxl] = NativeEndian::swapToLittleEndian(rgba);
+    }
+}
+
 void ConvolutionFilter::ConvolveHorizontally(const uint8_t* aSrc, uint8_t* aDst,
                                              bool aHasAlpha) {
+#if MOZ_BIG_ENDIAN()
+    int outputSize = mFilter->numValues();
+
+    // Input size isn't handed in, so we have to calculate it quickly
+    int inputSize = 0;
+    for (int xx = 0; xx < outputSize; ++xx) {
+        // Get the filter that determines the current output pixel.
+        int filterOffset, filterLength;
+        mFilter->FilterForValue(xx, &filterOffset, &filterLength);
+        inputSize = std::max(inputSize, filterOffset + filterLength);
+    }
+
+    ByteSwapArray((uint8_t*)aSrc, inputSize);
+#endif
+
   SkOpts::convolve_horizontally(aSrc, *mFilter, aDst, aHasAlpha);
+
+#if MOZ_BIG_ENDIAN()
+    ByteSwapArray((uint8_t*)aSrc, inputSize);
+    ByteSwapArray(aDst, outputSize);
+#endif
 }
 
 void ConvolutionFilter::ConvolveVertically(uint8_t* const* aSrc, uint8_t* aDst,
@@ -49,8 +78,26 @@
   int32_t filterLength;
   auto filterValues =
       mFilter->FilterForValue(aRowIndex, &filterOffset, &filterLength);
+
+#if MOZ_BIG_ENDIAN()
+  for (int filterY = 0; filterY < filterLength; filterY++) {
+      // Skia only knows LE, so we have to swizzle the input
+    ByteSwapArray(aSrc[filterY], aRowSize);
+  }
+#endif
+
   SkOpts::convolve_vertically(filterValues, filterLength, aSrc, aRowSize, aDst,
                               aHasAlpha);
+
+#if MOZ_BIG_ENDIAN()
+  // After skia is finished, we swizzle back to BE, in case
+  // the input is used again somewhere else
+  for (int filterY = 0; filterY < filterLength; filterY++) {
+    ByteSwapArray(aSrc[filterY], aRowSize);
+  }
+  // The destination array as well
+  ByteSwapArray(aDst, aRowSize);
+#endif
 }
 
 /* ConvolutionFilter::ComputeResizeFactor is derived from Skia's
diff -r 0e579dcbf732 gfx/skia/skia/include/core/SkPreConfig.h
--- a/gfx/skia/skia/include/core/SkPreConfig.h	Wed Jan 08 12:17:44 2020 +0100
+++ b/gfx/skia/skia/include/core/SkPreConfig.h	Wed Jan 08 12:17:49 2020 +0100
@@ -73,7 +73,7 @@
       defined(__ppc__) || defined(__hppa) || \
       defined(__PPC__) || defined(__PPC64__) || \
       defined(_MIPSEB) || defined(__ARMEB__) || \
-      defined(__s390__) || \
+      defined(__s390__) || defined(__s390x__) || \
       (defined(__sh__) && defined(__BIG_ENDIAN__)) || \
       (defined(__ia64) && defined(__BIG_ENDIAN__))
          #define SK_CPU_BENDIAN