[bigint] Implement Divide and Remainder

Bug: v8:6791
Change-Id: I5ab97feeb25da29bc76cd28088836b4f12d1d916
Reviewed-on: https://chromium-review.googlesource.com/678037
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Daniel Ehrenberg <littledan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48152}

src/base/bits.h

@@ -117,6 +117,7 @@ inline unsigned CountLeadingZeros64(uint64_t value) {
 #endif
 }
 
+DEFINE_32_64_OVERLOADS(CountLeadingZeros)
 
 // ReverseBits(value) returns |value| in reverse bit order.
 template <typename T>

src/messages.h

@@ -503,6 +503,7 @@ class ErrorUtils : public AllStatic {
   T(SuperAlreadyCalled, "Super constructor may only be called once")           \
   T(UnsupportedSuper, "Unsupported reference to 'super'")                      \
   /* RangeError */                                                             \
+  T(BigIntDivZero, "Division by zero")                                         \
   T(DateRange, "Provided date is not in valid range.")                         \
   T(ExpectedTimezoneID,                                                        \
     "Expected Area/Location(/Location)* for time zone, got %")                 \

src/objects/bigint.h

@@ -103,6 +103,26 @@ class BigInt : public HeapObject {
   static void MultiplyAccumulate(Handle<BigInt> multiplicand,
                                  digit_t multiplier, Handle<BigInt> accumulator,
                                  int accumulator_index);
+  static void InternalMultiplyAdd(BigInt* source, digit_t factor,
+                                  digit_t summand, int n, BigInt* result);
+
+  // Specialized helpers for Divide/Remainder.
+  static void AbsoluteDivSmall(Handle<BigInt> x, digit_t divisor,
+                               Handle<BigInt>* quotient, digit_t* remainder);
+  static void AbsoluteDivLarge(Handle<BigInt> dividend, Handle<BigInt> divisor,
+                               Handle<BigInt>* quotient,
+                               Handle<BigInt>* remainder);
+  static bool DoubleDigitGreaterThan(digit_t x_high, digit_t x_low,
+                                     digit_t y_high, digit_t y_low);
+  digit_t InplaceAdd(BigInt* summand, int start_index);
+  digit_t InplaceSub(BigInt* subtrahend, int start_index);
+  void InplaceRightShift(int shift);
+  enum SpecialLeftShiftMode {
+    kSameSizeResult,
+    kAlwaysAddOneDigit,
+  };
+  static Handle<BigInt> SpecialLeftShift(Handle<BigInt> x, int shift,
+                                         SpecialLeftShiftMode mode);
 
   static MaybeHandle<String> ToStringBasePowerOfTwo(Handle<BigInt> x,
                                                     int radix);
@@ -111,6 +131,8 @@ class BigInt : public HeapObject {
   static inline digit_t digit_add(digit_t a, digit_t b, digit_t* carry);
   static inline digit_t digit_sub(digit_t a, digit_t b, digit_t* borrow);
   static inline digit_t digit_mul(digit_t a, digit_t b, digit_t* high);
+  static inline digit_t digit_div(digit_t high, digit_t low, digit_t divisor,
+                                  digit_t* remainder);
 
   class LengthBits : public BitField<int, 0, kMaxLengthBits> {};
   class SignBits : public BitField<bool, LengthBits::kNext, 1> {};