diff -r 84cdfb476431 -r 8e9195853a32 mozilla-bmo1504834-part2.patch
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mozilla-bmo1504834-part2.patch	Tue Nov 19 22:54:22 2019 +0100
@@ -0,0 +1,112 @@
+# HG changeset patch
+# Parent  6fa4b62427433e8f445d05c557e5db096667d880
+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 --git a/gfx/2d/ConvolutionFilter.cpp b/gfx/2d/ConvolutionFilter.cpp
+--- a/gfx/2d/ConvolutionFilter.cpp
++++ b/gfx/2d/ConvolutionFilter.cpp
+@@ -30,32 +30,79 @@ bool ConvolutionFilter::GetFilterOffsetA
+                                                  int32_t* aResultLength) {
+   if (aRowIndex >= mFilter->numValues()) {
+     return false;
+   }
+   mFilter->FilterForValue(aRowIndex, aResultOffset, aResultLength);
+   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,
+                                            int32_t aRowIndex, int32_t aRowSize,
+                                            bool aHasAlpha) {
+   MOZ_ASSERT(aRowIndex < mFilter->numValues());
+ 
+   int32_t filterOffset;
+   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
+  * SkBitmapScaler/SkResizeFilter::computeFactors. It is governed by Skia's
+  * BSD-style license (see gfx/skia/LICENSE) and the following copyright:
+  * Copyright (c) 2015 Google Inc.
+  */
+ bool ConvolutionFilter::ComputeResizeFilter(ResizeMethod aResizeMethod,
+diff --git a/gfx/skia/skia/include/core/SkPreConfig.h b/gfx/skia/skia/include/core/SkPreConfig.h
+--- a/gfx/skia/skia/include/core/SkPreConfig.h
++++ b/gfx/skia/skia/include/core/SkPreConfig.h
+@@ -68,17 +68,17 @@
+         #define SK_CPU_BENDIAN
+     #elif defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
+         #define SK_CPU_LENDIAN
+     #elif defined(__sparc) || defined(__sparc__) || \
+       defined(_POWER) || defined(__powerpc__) || \
+       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
+     #else
+         #define SK_CPU_LENDIAN
+     #endif
+ #endif
+