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-rw-r--r--dom/base/nsTextFragmentVMX.cpp101
1 files changed, 101 insertions, 0 deletions
diff --git a/dom/base/nsTextFragmentVMX.cpp b/dom/base/nsTextFragmentVMX.cpp
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+++ 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