[turbofan][arm64] Match add with shifted operand for mult by a power of 2 plus 1.

src/utils.h

 // 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.
 
 #ifndef V8_UTILS_H_
 #define V8_UTILS_H_
 
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 49 matching lines @@
     case 8: bits++;  // Fall through.
     case 4: bits++;  // Fall through.
     case 2: bits++;  // Fall through.
     case 1: break;
   }
   DCHECK_EQ(1 << bits, original_x);
   return bits;
 }
 
 
+// X must be a power of 2.  Returns the number of trailing zeros.
+inline int WhichPowerOf2_64(uint64_t x) {
+  DCHECK(base::bits::IsPowerOfTwo64(x));
+  int bits = 0;
+#ifdef DEBUG
+  uint64_t original_x = x;
+#endif
+  if (x >= 0x100000000L) {
+    bits += 32;
+    x >>= 32;
+  }
+  if (x >= 0x10000) {
+    bits += 16;
+    x >>= 16;
+  }
+  if (x >= 0x100) {
+    bits += 8;
+    x >>= 8;
+  }
+  if (x >= 0x10) {
+    bits += 4;
+    x >>= 4;
+  }
+  switch (x) {
+    default: UNREACHABLE();
+    case 8: bits++;  // Fall through.
+    case 4: bits++;  // Fall through.
+    case 2: bits++;  // Fall through.
+    case 1: break;
+  }
+  DCHECK_EQ(1L << bits, original_x);
+  return bits;
+}
+
+
 inline int MostSignificantBit(uint32_t x) {
   static const int msb4[] = {0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4};
   int nibble = 0;
   if (x & 0xffff0000) {
     nibble += 16;
     x >>= 16;
   }
   if (x & 0xff00) {
     nibble += 8;
     x >>= 8;
@@ skipping 1595 matching lines @@
   // Takes the address of the limit variable in order to find out where
   // the top of stack is right now.
   uintptr_t limit = reinterpret_cast<uintptr_t>(&limit);
   return limit;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UTILS_H_