Simplify powers-of-ten cache.

src/fast-dtoa.cc

 // Copyright 2010 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 591 matching lines @@
   DiyFp w = Double(v).AsNormalizedDiyFp();
   // boundary_minus and boundary_plus are the boundaries between v and its
   // closest floating-point neighbors. Any number strictly between
   // boundary_minus and boundary_plus will round to v when convert to a double.
   // Grisu3 will never output representations that lie exactly on a boundary.
   DiyFp boundary_minus, boundary_plus;
   Double(v).NormalizedBoundaries(&boundary_minus, &boundary_plus);
   ASSERT(boundary_plus.e() == w.e());
   DiyFp ten_mk;  // Cached power of ten: 10^-k
   int mk;        // -k
-  GetCachedPower(w.e() + DiyFp::kSignificandSize, kMinimalTargetExponent,
-                 kMaximalTargetExponent, &mk, &ten_mk);
+  int ten_mk_minimal_binary_exponent =
+     kMinimalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  int ten_mk_maximal_binary_exponent =
+     kMaximalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  GetCachedPowerForBinaryExponentRange(ten_mk_minimal_binary_exponent,
+                                       ten_mk_maximal_binary_exponent,
+                                       &ten_mk, &mk);
   ASSERT((kMinimalTargetExponent <= w.e() + ten_mk.e() +
           DiyFp::kSignificandSize) &&
          (kMaximalTargetExponent >= w.e() + ten_mk.e() +
           DiyFp::kSignificandSize));
   // Note that ten_mk is only an approximation of 10^-k. A DiyFp only contains a
   // 64 bit significand and ten_mk is thus only precise up to 64 bits.
 
   // The DiyFp::Times procedure rounds its result, and ten_mk is approximated
   // too. The variable scaled_w (as well as scaled_boundary_minus/plus) are now
   // off by a small amount.
@@ skipping 31 matching lines @@
 // Grisu3 is too imprecise for real halfway cases (1.5 will not work) and
 // therefore the rounding strategy for halfway cases is irrelevant.
 static bool Grisu3Counted(double v,
                           int requested_digits,
                           Vector<char> buffer,
                           int* length,
                           int* decimal_exponent) {
   DiyFp w = Double(v).AsNormalizedDiyFp();
   DiyFp ten_mk;  // Cached power of ten: 10^-k
   int mk;        // -k
-  GetCachedPower(w.e() + DiyFp::kSignificandSize, kMinimalTargetExponent,
-                 kMaximalTargetExponent, &mk, &ten_mk);
+  int ten_mk_minimal_binary_exponent =
+     kMinimalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  int ten_mk_maximal_binary_exponent =
+     kMaximalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  GetCachedPowerForBinaryExponentRange(ten_mk_minimal_binary_exponent,
+                                       ten_mk_maximal_binary_exponent,
+                                       &ten_mk, &mk);
   ASSERT((kMinimalTargetExponent <= w.e() + ten_mk.e() +
           DiyFp::kSignificandSize) &&
          (kMaximalTargetExponent >= w.e() + ten_mk.e() +
           DiyFp::kSignificandSize));
   // Note that ten_mk is only an approximation of 10^-k. A DiyFp only contains a
   // 64 bit significand and ten_mk is thus only precise up to 64 bits.
 
   // The DiyFp::Times procedure rounds its result, and ten_mk is approximated
   // too. The variable scaled_w (as well as scaled_boundary_minus/plus) are now
   // off by a small amount.
@@ skipping 38 matching lines @@
       UNREACHABLE();
   }
   if (result) {
     *decimal_point = *length + decimal_exponent;
     buffer[*length] = '\0';
   }
   return result;
 }
 
 } }  // namespace v8::internal