Revert "Remove V8_HOST_CAN_READ_UNALIGNED and its uses."

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 #include <limits>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 6534 matching lines @@
   DisallowHeapAllocation no_gc;
   // We rely on the distance between upper and lower case letters
   // being a known power of 2.
   DCHECK('a' - 'A' == (1 << 5));
   // Boundaries for the range of input characters than require conversion.
   static const char lo = Converter::kIsToLower ? 'A' - 1 : 'a' - 1;
   static const char hi = Converter::kIsToLower ? 'Z' + 1 : 'z' + 1;
   bool changed = false;
   uintptr_t or_acc = 0;
   const char* const limit = src + length;
-
-  // dst is newly allocated and always aligned.
-  DCHECK(IsAligned(reinterpret_cast<intptr_t>(dst), sizeof(uintptr_t)));
-  // Only attempt processing one word at a time if src is also aligned.
-  if (IsAligned(reinterpret_cast<intptr_t>(src), sizeof(uintptr_t))) {
-    // Process the prefix of the input that requires no conversion one aligned
-    // (machine) word at a time.
-    while (src <= limit - sizeof(uintptr_t)) {
-      const uintptr_t w = *reinterpret_cast<const uintptr_t*>(src);
-      or_acc |= w;
-      if (AsciiRangeMask(w, lo, hi) != 0) {
-        changed = true;
-        break;
-      }
-      *reinterpret_cast<uintptr_t*>(dst) = w;
-      src += sizeof(uintptr_t);
-      dst += sizeof(uintptr_t);
+#ifdef V8_HOST_CAN_READ_UNALIGNED
+  // Process the prefix of the input that requires no conversion one
+  // (machine) word at a time.
+  while (src <= limit - sizeof(uintptr_t)) {
+    const uintptr_t w = *reinterpret_cast<const uintptr_t*>(src);
+    or_acc |= w;
+    if (AsciiRangeMask(w, lo, hi) != 0) {
+      changed = true;
+      break;
     }
-    // Process the remainder of the input performing conversion when
-    // required one word at a time.
-    while (src <= limit - sizeof(uintptr_t)) {
-      const uintptr_t w = *reinterpret_cast<const uintptr_t*>(src);
-      or_acc |= w;
-      uintptr_t m = AsciiRangeMask(w, lo, hi);
-      // The mask has high (7th) bit set in every byte that needs
-      // conversion and we know that the distance between cases is
-      // 1 << 5.
-      *reinterpret_cast<uintptr_t*>(dst) = w ^ (m >> 2);
-      src += sizeof(uintptr_t);
-      dst += sizeof(uintptr_t);
-    }
+    *reinterpret_cast<uintptr_t*>(dst) = w;
+    src += sizeof(uintptr_t);
+    dst += sizeof(uintptr_t);
   }
+  // Process the remainder of the input performing conversion when
+  // required one word at a time.
+  while (src <= limit - sizeof(uintptr_t)) {
+    const uintptr_t w = *reinterpret_cast<const uintptr_t*>(src);
+    or_acc |= w;
+    uintptr_t m = AsciiRangeMask(w, lo, hi);
+    // The mask has high (7th) bit set in every byte that needs
+    // conversion and we know that the distance between cases is
+    // 1 << 5.
+    *reinterpret_cast<uintptr_t*>(dst) = w ^ (m >> 2);
+    src += sizeof(uintptr_t);
+    dst += sizeof(uintptr_t);
+  }
+#endif
   // Process the last few bytes of the input (or the whole input if
   // unaligned access is not supported).
   while (src < limit) {
     char c = *src;
     or_acc |= c;
     if (lo < c && c < hi) {
       c ^= (1 << 5);
       changed = true;
     }
     *dst = c;
     ++src;
     ++dst;
   }
-
-  if ((or_acc & kAsciiMask) != 0) return false;
+  if ((or_acc & kAsciiMask) != 0) {
+    return false;
+  }
 
   DCHECK(CheckFastAsciiConvert(
              saved_dst, saved_src, length, changed, Converter::kIsToLower));
 
   *changed_out = changed;
   return true;
 }
 
 }  // namespace
 
@@ skipping 9069 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal