1 files changed, 101 insertions, 0 deletions
diff --git a/dom/base/nsTextFragmentVMX.cpp b/dom/base/nsTextFragmentVMX.cpp
new file mode 100644
index 0000000000..a071adaee7
--- /dev/null
+++ b/dom/base/nsTextFragmentVMX.cpp
@@ -0,0 +1,101 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This file should only be compiled if you're on Power ISA.
+
+#include "nscore.h"
+#include "nsAlgorithm.h"
+#include "nsTextFragmentImpl.h"
+#include <algorithm>
+#include <altivec.h>
+
+namespace mozilla {
+namespace VMX {
+
+int32_t FirstNon8Bit(const char16_t* str, const char16_t* end) {
+  const uint32_t numUnicharsPerVector = 8;
+  const uint32_t numCharsPerVector = 16;
+  // Paranoia. If this assertion is wrong, change the vector loop below.
+  MOZ_ASSERT((numCharsPerVector / numUnicharsPerVector) == sizeof(char16_t));
+
+  typedef Non8BitParameters<sizeof(size_t)> p;
+  const uint32_t alignMask = p::alignMask();
+  const size_t mask = p::mask();
+  const uint32_t numUnicharsPerWord = p::numUnicharsPerWord();
+
+  const uint32_t len = end - str;
+
+  // i shall count the index in unichars; i2 shall count the index in chars.
+  uint32_t i = 0;
+  uint32_t i2 = 0;
+
+  // Align ourselves to a 16-byte boundary, as required by VMX loads.
+  uint32_t alignLen = std::min(
+      len, uint32_t(((-NS_PTR_TO_UINT32(str)) & 0xf) / sizeof(char16_t)));
+
+  if ((len - alignLen) >= numUnicharsPerVector) {
+    for (; i < alignLen; i++) {
+      if (str[i] > 255) return i;
+    }
+
+    // Construct a vector of shorts.
+#if __LITTLE_ENDIAN__
+    const vector unsigned short gtcompare =
+        reinterpret_cast<vector unsigned short>(
+            vec_mergel(vec_splat_s8(-1), vec_splat_s8(0)));
+#else
+    const vector unsigned short gtcompare =
+        reinterpret_cast<vector unsigned short>(
+            vec_mergel(vec_splat_s8(0), vec_splat_s8(-1)));
+#endif
+    const uint32_t vectWalkEnd =
+        ((len - i) / numUnicharsPerVector) * numUnicharsPerVector;
+    i2 = i * sizeof(char16_t);
+
+    while (1) {
+      vector unsigned short vect;
+
+      // Check one VMX register (8 unichars) at a time. The vec_any_gt
+      // intrinsic does exactly what we want. This loop is manually unrolled;
+      // it yields notable performance improvements this way.
+#define CheckForASCII                                              \
+  vect = vec_ld(i2, reinterpret_cast<const unsigned short*>(str)); \
+  if (vec_any_gt(vect, gtcompare)) return i;                       \
+  i += numUnicharsPerVector;                                       \
+  if (!(i < vectWalkEnd)) break;                                   \
+  i2 += numCharsPerVector;
+
+      CheckForASCII CheckForASCII
+
+#undef CheckForASCII
+    }
+  } else {
+    // Align ourselves to a word boundary.
+    alignLen = std::min(len, uint32_t(((-NS_PTR_TO_UINT32(str)) & alignMask) /
+                                      sizeof(char16_t)));
+    for (; i < alignLen; i++) {
+      if (str[i] > 255) return i;
+    }
+  }
+
+  // Check one word at a time.
+  const uint32_t wordWalkEnd =
+      ((len - i) / numUnicharsPerWord) * numUnicharsPerWord;
+  for (; i < wordWalkEnd; i += numUnicharsPerWord) {
+    const size_t word = *reinterpret_cast<const size_t*>(str + i);
+    if (word & mask) return i;
+  }
+
+  // Take care of the remainder one character at a time.
+  for (; i < len; i++) {
+    if (str[i] > 255) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+}  // namespace VMX
+}  // namespace mozilla