ARM: Implement memcpy using NEON.

src/v8utils.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 299 matching lines @@
                             bool verbose = true);
 Vector<const char> ReadFile(FILE* file,
                             bool* exists,
                             bool verbose = true);
 
 
 template <typename sourcechar, typename sinkchar>
 INLINE(static void CopyCharsUnsigned(sinkchar* dest,
                                      const sourcechar* src,
                                      int chars));
+#if defined(V8_HOST_ARCH_ARM)
+INLINE(void CopyCharsUnsigned(uint8_t* dest, const uint8_t* src, int chars));
+INLINE(void CopyCharsUnsigned(uint16_t* dest, const uint8_t* src, int chars));
+INLINE(void CopyCharsUnsigned(uint16_t* dest, const uint16_t* src, int chars));
+#endif
 
 // Copy from ASCII/16bit chars to ASCII/16bit chars.
 template <typename sourcechar, typename sinkchar>
 INLINE(void CopyChars(sinkchar* dest, const sourcechar* src, int chars));
 
 template<typename sourcechar, typename sinkchar>
 void CopyChars(sinkchar* dest, const sourcechar* src, int chars) {
   ASSERT(sizeof(sourcechar) <= 2);
   ASSERT(sizeof(sinkchar) <= 2);
   if (sizeof(sinkchar) == 1) {
@@ skipping 38 matching lines @@
       src += kStepSize;
     }
   }
 #endif
   while (dest < limit) {
     *dest++ = static_cast<sinkchar>(*src++);
   }
 }
 
 
+#if defined(V8_HOST_ARCH_ARM)
+void CopyCharsUnsigned(uint8_t* dest, const uint8_t* src, int chars) {
+  switch (static_cast<unsigned>(chars)) {
+    case 0:
+      break;
+    case 1:
+      *dest = *src;
+      break;
+    case 2:
+      memcpy(dest, src, 2);
+      break;
+    case 3:
+      memcpy(dest, src, 3);
+      break;
+    case 4:
+      memcpy(dest, src, 4);
+      break;
+    case 5:
+      memcpy(dest, src, 5);
+      break;
+    case 6:
+      memcpy(dest, src, 6);
+      break;
+    case 7:
+      memcpy(dest, src, 7);
+      break;
+    case 8:
+      memcpy(dest, src, 8);
+      break;
+    case 9:
+      memcpy(dest, src, 9);
+      break;
+    case 10:
+      memcpy(dest, src, 10);
+      break;
+    case 11:
+      memcpy(dest, src, 11);
+      break;
+    case 12:
+      memcpy(dest, src, 12);
+      break;
+    case 13:
+      memcpy(dest, src, 13);
+      break;
+    case 14:
+      memcpy(dest, src, 14);
+      break;
+    case 15:
+      memcpy(dest, src, 15);

[ulan, 2013/07/09 15:16:32]

OK, if this gives perf. improvement compared to memcpy(dest, src, chars).

[vincent.belliard.fr, 2013/07/10 15:30:38]

This gives good improvement. For small known sizes, gcc generates the good
instructions (ldrb, ldrh, ldr) to copy the needed size.

+      break;
+    default:
+      OS::MemCopy(dest, src, chars);
+      break;
+  }
+}
+
+
+void CopyCharsUnsigned(uint16_t* dest, const uint8_t* src, int chars) {
+  if (chars >= OS::kMinComplexConvertMemCopy) {
+    OS::MemCopyUint16Uint8(dest, src, chars);
+  } else {
+    OS::MemCopyUint16Uint8Wrapper(dest, src, chars);
+  }
+}
+
+
+void CopyCharsUnsigned(uint16_t* dest, const uint16_t* src, int chars) {
+  switch (static_cast<unsigned>(chars)) {
+    case 0:
+      break;
+    case 1:
+      *dest = *src;
+      break;
+    case 2:
+      memcpy(dest, src, 4);
+      break;
+    case 3:
+      memcpy(dest, src, 6);
+      break;
+    case 4:
+      memcpy(dest, src, 8);
+      break;
+    case 5:
+      memcpy(dest, src, 10);
+      break;
+    case 6:
+      memcpy(dest, src, 12);
+      break;
+    case 7:
+      memcpy(dest, src, 14);
+      break;
+    default:
+      OS::MemCopy(dest, src, chars * sizeof(*dest));
+      break;
+  }
+}
+#endif
+
+
 class StringBuilder : public SimpleStringBuilder {
  public:
   explicit StringBuilder(int size) : SimpleStringBuilder(size) { }
   StringBuilder(char* buffer, int size) : SimpleStringBuilder(buffer, size) { }
 
   // Add formatted contents to the builder just like printf().
   void AddFormatted(const char* format, ...);
 
   // Add formatted contents like printf based on a va_list.
   void AddFormattedList(const char* format, va_list list);
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_V8UTILS_H_