Changeset 231845 in webkit

Timestamp:

May 16, 2018 7:26:30 AM (6 years ago)

Author:

Caio Lima

Message:

[ESNext][BigInt] Implement support for "/" operation
​https://bugs.webkit.org/show_bug.cgi?id=183996

Reviewed by Yusuke Suzuki.

JSTests:

• bigIntTests.yaml:
• stress/big-int-div-jit.js: Added.
• stress/big-int-div-memory-stress.js: Added.
• stress/big-int-div-to-primitive-precedence.js: Added.
• stress/big-int-div-to-primitive.js: Added.
• stress/big-int-div-type-error.js: Added.
• stress/big-int-div-wrapped-value.js: Added.
• stress/big-int-division.js: Added.

Source/JavaScriptCore:

This patch is introducing the support for BigInt into divide
operation int LLInt and JIT layers.

• dfg/DFGOperations.cpp:
• runtime/CommonSlowPaths.cpp:

(JSC::SLOW_PATH_DECL):

• runtime/JSBigInt.cpp:

(JSC::JSBigInt::divide):
(JSC::JSBigInt::copy):
(JSC::JSBigInt::unaryMinus):
(JSC::JSBigInt::absoluteCompare):
(JSC::JSBigInt::absoluteDivLarge):
(JSC::JSBigInt::productGreaterThan):
(JSC::JSBigInt::inplaceAdd):
(JSC::JSBigInt::inplaceSub):
(JSC::JSBigInt::inplaceRightShift):
(JSC::JSBigInt::specialLeftShift):
(JSC::JSBigInt::digit):
(JSC::JSBigInt::setDigit):

• runtime/JSBigInt.h:

Location:

trunk

Files:

• JSTests/ChangeLog (modified) (1 diff)
• JSTests/bigIntTests.yaml (modified) (1 diff)
• JSTests/stress/big-int-div-jit.js (added)
• JSTests/stress/big-int-div-memory-stress.js (added)
• JSTests/stress/big-int-div-to-primitive.js (added)
• JSTests/stress/big-int-div-type-error.js (added)
• JSTests/stress/big-int-div-wrapped-value.js (added)
• JSTests/stress/big-int-division.js (added)
• Source/JavaScriptCore/ChangeLog (modified) (1 diff)
• Source/JavaScriptCore/dfg/DFGOperations.cpp (modified) (2 diffs)
• Source/JavaScriptCore/runtime/BigIntPrototype.cpp (modified) (1 diff)
• Source/JavaScriptCore/runtime/CommonSlowPaths.cpp (modified) (1 diff)
• Source/JavaScriptCore/runtime/JSBigInt.cpp (modified) (11 diffs)
• Source/JavaScriptCore/runtime/JSBigInt.h (modified) (5 diffs)
• Source/JavaScriptCore/runtime/JSCJSValue.cpp (modified) (1 diff)

trunk/JSTests/ChangeLog

@@ +1 @@
+2018-05-16  Caio Lima  <ticaiolima@gmail.com>
+
+        [ESNext][BigInt] Implement support for "/" operation
+        https://bugs.webkit.org/show_bug.cgi?id=183996
+
+        Reviewed by Yusuke Suzuki.
+
+        * bigIntTests.yaml:
+        * stress/big-int-div-jit.js: Added.
+        * stress/big-int-div-memory-stress.js: Added.
+        * stress/big-int-div-to-primitive-precedence.js: Added.
+        * stress/big-int-div-to-primitive.js: Added.
+        * stress/big-int-div-type-error.js: Added.
+        * stress/big-int-div-wrapped-value.js: Added.
+        * stress/big-int-division.js: Added.
+
 2018-05-14  Leo Balter  <leonardo.balter@gmail.com>
 

trunk/JSTests/bigIntTests.yaml

@@ -119 +119 @@
   cmd: runBigIntEnabled
 
+- path: stress/big-int-div-jit.js
+  cmd: runBigIntEnabled
+
+- path: stress/big-int-div-memory-stress.js
+  cmd: runBigIntEnabled
+
+- path: stress/big-int-div-to-primitive.js
+  cmd: runBigIntEnabled
+
+- path: stress/big-int-div-type-error.js
+  cmd: runBigIntEnabled
+
+- path: stress/big-int-div-wrapped-value.js
+  cmd: runBigIntEnabled
+
+- path: stress/big-int-division.js
+  cmd: runBigIntEnabled

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2018-05-16  Caio Lima  <ticaiolima@gmail.com>
+
+        [ESNext][BigInt] Implement support for "/" operation
+        https://bugs.webkit.org/show_bug.cgi?id=183996
+
+        Reviewed by Yusuke Suzuki.
+
+        This patch is introducing the support for BigInt into divide
+        operation int LLInt and JIT layers.
+
+        * dfg/DFGOperations.cpp:
+        * runtime/CommonSlowPaths.cpp:
+        (JSC::SLOW_PATH_DECL):
+        * runtime/JSBigInt.cpp:
+        (JSC::JSBigInt::divide):
+        (JSC::JSBigInt::copy):
+        (JSC::JSBigInt::unaryMinus):
+        (JSC::JSBigInt::absoluteCompare):
+        (JSC::JSBigInt::absoluteDivLarge):
+        (JSC::JSBigInt::productGreaterThan):
+        (JSC::JSBigInt::inplaceAdd):
+        (JSC::JSBigInt::inplaceSub):
+        (JSC::JSBigInt::inplaceRightShift):
+        (JSC::JSBigInt::specialLeftShift):
+        (JSC::JSBigInt::digit):
+        (JSC::JSBigInt::setDigit):
+        * runtime/JSBigInt.h:
+
 2018-05-16  Alberto Garcia  <berto@igalia.com>
 

trunk/Source/JavaScriptCore/dfg/DFGOperations.cpp

@@ -76 +76 @@
 #include "VMInlines.h"
 #include <wtf/InlineASM.h>
+#include <wtf/Variant.h>
 
 #if ENABLE(JIT)
@@ -425 +426 @@
     JSValue op2 = JSValue::decode(encodedOp2);
 
-    double a = op1.toNumber(exec);
+    auto leftNumeric = op1.toNumeric(exec);
     RETURN_IF_EXCEPTION(scope, encodedJSValue());
+    auto rightNumeric = op2.toNumeric(exec);
+    RETURN_IF_EXCEPTION(scope, encodedJSValue());
+
+    if (WTF::holds_alternative<JSBigInt*>(leftNumeric) || WTF::holds_alternative<JSBigInt*>(rightNumeric)) {
+        if (WTF::holds_alternative<JSBigInt*>(leftNumeric) && WTF::holds_alternative<JSBigInt*>(rightNumeric)) {
+            JSBigInt* result = JSBigInt::divide(exec, WTF::get<JSBigInt*>(leftNumeric), WTF::get<JSBigInt*>(rightNumeric));
+            RETURN_IF_EXCEPTION(scope, encodedJSValue());
+            return JSValue::encode(result);
+        }
+
+        return throwVMTypeError(exec, scope, "Invalid operand in BigInt operation.");
+    }
+
     scope.release();
-    double b = op2.toNumber(exec);
+
+    double a = WTF::get<double>(leftNumeric);
+    double b = WTF::get<double>(rightNumeric);
     return JSValue::encode(jsNumber(a / b));
 }

trunk/Source/JavaScriptCore/runtime/BigIntPrototype.cpp

@@ -104 +104 @@
     RETURN_IF_EXCEPTION(scope, encodedJSValue());
 
-    String resultString = value->toString(*state, radix);
+    String resultString = value->toString(state, radix);
     RETURN_IF_EXCEPTION(scope, encodedJSValue());
     scope.release();

trunk/Source/JavaScriptCore/runtime/CommonSlowPaths.cpp

@@ -517 +517 @@
     JSValue left = OP_C(2).jsValue();
     JSValue right = OP_C(3).jsValue();
-    double a = left.toNumber(exec);
-    if (UNLIKELY(throwScope.exception()))
-        RETURN(JSValue());
-    double b = right.toNumber(exec);
-    if (UNLIKELY(throwScope.exception()))
-        RETURN(JSValue());
+    auto leftNumeric = left.toNumeric(exec);
+    CHECK_EXCEPTION();
+    auto rightNumeric = right.toNumeric(exec);
+    CHECK_EXCEPTION();
+
+    if (WTF::holds_alternative<JSBigInt*>(leftNumeric) || WTF::holds_alternative<JSBigInt*>(rightNumeric)) {
+        if (WTF::holds_alternative<JSBigInt*>(leftNumeric) && WTF::holds_alternative<JSBigInt*>(rightNumeric)) {
+            JSValue result(JSBigInt::divide(exec, WTF::get<JSBigInt*>(leftNumeric), WTF::get<JSBigInt*>(rightNumeric)));
+            CHECK_EXCEPTION();
+            RETURN_WITH_PROFILING(result, {
+                updateArithProfileForBinaryArithOp(exec, pc, result, left, right);
+            });
+        }
+
+        THROW(createTypeError(exec, "Invalid mix of BigInt and other type in division."));
+    }
+
+    double a = WTF::get<double>(leftNumeric);
+    double b = WTF::get<double>(rightNumeric);
     JSValue result = jsNumber(a / b);
     RETURN_WITH_PROFILING(result, {

trunk/Source/JavaScriptCore/runtime/JSBigInt.cpp

@@ -228 +228 @@
 }
 
-String JSBigInt::toString(ExecState& state, unsigned radix)
+String JSBigInt::toString(ExecState* state, unsigned radix)
 {
     if (this->isZero())
-        return state.vm().smallStrings.singleCharacterStringRep('0');
+        return state->vm().smallStrings.singleCharacterStringRep('0');
 
     return toStringGeneric(state, this, radix);
@@ -269 +269 @@
     result->setSign(x->sign() != y->sign());
     return result->rightTrim(vm);
+}
+
+JSBigInt* JSBigInt::divide(ExecState* state, JSBigInt* x, JSBigInt* y)
+{
+    // 1. If y is 0n, throw a RangeError exception.
+    VM& vm = state->vm();
+    auto scope = DECLARE_THROW_SCOPE(vm);
+
+    if (y->isZero()) {
+        throwRangeError(state, scope, ASCIILiteral("0 is an invalid divisor value."));
+        return nullptr;
+    }
+
+    // 2. Let quotient be the mathematical value of x divided by y.
+    // 3. Return a BigInt representing quotient rounded towards 0 to the next
+    //    integral value.
+    if (absoluteCompare(x, y) == ComparisonResult::LessThan)
+        return createZero(vm);
+
+    JSBigInt* quotient = nullptr;
+    bool resultSign = x->sign() != y->sign();
+    if (y->length() == 1) {
+        Digit divisor = y->digit(0);
+        if (divisor == 1)
+            return resultSign == x->sign() ? x : unaryMinus(vm, x);
+
+        Digit remainder;
+        absoluteDivWithDigitDivisor(vm, x, divisor, &quotient, remainder);
+    } else
+        absoluteDivWithBigIntDivisor(vm, x, y, &quotient, nullptr);
+
+    quotient->setSign(resultSign);
+    return quotient->rightTrim(vm);
+}
+
+JSBigInt* JSBigInt::copy(VM& vm, JSBigInt* x)
+{
+    ASSERT(!x->isZero());
+
+    JSBigInt* result = JSBigInt::createWithLength(vm, x->length());
+    std::copy(x->dataStorage(), x->dataStorage() + x->length(), result->dataStorage());
+    result->setSign(x->sign());
+    return result;
+}
+
+JSBigInt* JSBigInt::unaryMinus(VM& vm, JSBigInt* x)
+{
+    if (x->isZero())
+        return x;
+
+    JSBigInt* result = copy(vm, x);
+    result->setSign(!x->sign());
+    return result;
 }
 
@@ -523 +576 @@
 }
 
+inline JSBigInt::ComparisonResult JSBigInt::absoluteCompare(JSBigInt* x, JSBigInt* y)
+{
+    ASSERT(!x->length() || x->digit(0));
+    ASSERT(!y->length() || y->digit(0));
+
+    int diff = x->length() - y->length();
+    if (diff)
+        return diff < 0 ? ComparisonResult::LessThan : ComparisonResult::GreaterThan;
+
+    int i = x->length() - 1;
+    while (i >= 0 && x->digit(i) == y->digit(i))
+        i--;
+
+    if (i < 0)
+        return ComparisonResult::Equal;
+
+    return x->digit(i) > y->digit(i) ? ComparisonResult::GreaterThan : ComparisonResult::LessThan;
+}
+
 // Divides {x} by {divisor}, returning the result in {quotient} and {remainder}.
 // Mathematically, the contract is:
@@ -530 +602 @@
 // {quotient} can be the same as {x} for an in-place division. {quotient} can
 // also be nullptr if the caller is only interested in the remainder.
-void JSBigInt::absoluteDivSmall(ExecState& state, JSBigInt* x, Digit divisor, JSBigInt** quotient, Digit& remainder)
+void JSBigInt::absoluteDivWithDigitDivisor(VM& vm, JSBigInt* x, Digit divisor, JSBigInt** quotient, Digit& remainder)
 {
     ASSERT(divisor);
 
-    VM& vm = state.vm();
     ASSERT(!x->isZero());
     remainder = 0;
@@ -556 +627 @@
             digitDiv(remainder, x->digit(i), divisor, remainder);
     }
+}
+
+// Divides {dividend} by {divisor}, returning the result in {quotient} and
+// {remainder}. Mathematically, the contract is:
+// quotient = (dividend - remainder) / divisor, with 0 <= remainder < divisor.
+// Both {quotient} and {remainder} are optional, for callers that are only
+// interested in one of them.
+// See Knuth, Volume 2, section 4.3.1, Algorithm D.
+void JSBigInt::absoluteDivWithBigIntDivisor(VM& vm, JSBigInt* dividend, JSBigInt* divisor, JSBigInt** quotient, JSBigInt** remainder)
+{
+    ASSERT(divisor->length() >= 2);
+    ASSERT(dividend->length() >= divisor->length());
+
+    // The unusual variable names inside this function are consistent with
+    // Knuth's book, as well as with Go's implementation of this algorithm.
+    // Maintaining this consistency is probably more useful than trying to
+    // come up with more descriptive names for them.
+    unsigned n = divisor->length();
+    unsigned m = dividend->length() - n;
+    
+    // The quotient to be computed.
+    JSBigInt* q = nullptr;
+    if (quotient != nullptr)
+        q = createWithLength(vm, m + 1);
+    
+    // In each iteration, {qhatv} holds {divisor} * {current quotient digit}.
+    // "v" is the book's name for {divisor}, "qhat" the current quotient digit.
+    JSBigInt* qhatv = createWithLength(vm, m + 1);
+    
+    // D1.
+    // Left-shift inputs so that the divisor's MSB is set. This is necessary
+    // to prevent the digit-wise divisions (see digit_div call below) from
+    // overflowing (they take a two digits wide input, and return a one digit
+    // result).
+    Digit lastDigit = divisor->digit(n - 1);
+    unsigned shift = sizeof(lastDigit) == 8 ? clz64(lastDigit) : clz32(lastDigit);
+
+    if (shift > 0)
+        divisor = absoluteLeftShiftAlwaysCopy(vm, divisor, shift, LeftShiftMode::SameSizeResult);
+
+    // Holds the (continuously updated) remaining part of the dividend, which
+    // eventually becomes the remainder.
+    JSBigInt* u = absoluteLeftShiftAlwaysCopy(vm, dividend, shift, LeftShiftMode::AlwaysAddOneDigit);
+
+    // D2.
+    // Iterate over the dividend's digit (like the "grad school" algorithm).
+    // {vn1} is the divisor's most significant digit.
+    Digit vn1 = divisor->digit(n - 1);
+    for (int j = m; j >= 0; j--) {
+        // D3.
+        // Estimate the current iteration's quotient digit (see Knuth for details).
+        // {qhat} is the current quotient digit.
+        Digit qhat = std::numeric_limits<Digit>::max();
+
+        // {ujn} is the dividend's most significant remaining digit.
+        Digit ujn = u->digit(j + n);
+        if (ujn != vn1) {
+            // {rhat} is the current iteration's remainder.
+            Digit rhat = 0;
+            // Estimate the current quotient digit by dividing the most significant
+            // digits of dividend and divisor. The result will not be too small,
+            // but could be a bit too large.
+            qhat = digitDiv(ujn, u->digit(j + n - 1), vn1, rhat);
+            
+            // Decrement the quotient estimate as needed by looking at the next
+            // digit, i.e. by testing whether
+            // qhat * v_{n-2} > (rhat << digitBits) + u_{j+n-2}.
+            Digit vn2 = divisor->digit(n - 2);
+            Digit ujn2 = u->digit(j + n - 2);
+            while (productGreaterThan(qhat, vn2, rhat, ujn2)) {
+                qhat--;
+                Digit prevRhat = rhat;
+                rhat += vn1;
+                // v[n-1] >= 0, so this tests for overflow.
+                if (rhat < prevRhat)
+                    break;
+            }
+        }
+
+        // D4.
+        // Multiply the divisor with the current quotient digit, and subtract
+        // it from the dividend. If there was "borrow", then the quotient digit
+        // was one too high, so we must correct it and undo one subtraction of
+        // the (shifted) divisor.
+        internalMultiplyAdd(divisor, qhat, 0, n, qhatv);
+        Digit c = u->absoluteInplaceSub(qhatv, j);
+        if (c) {
+            c = u->absoluteInplaceAdd(divisor, j);
+            u->setDigit(j + n, u->digit(j + n) + c);
+            qhat--;
+        }
+        
+        if (quotient != nullptr)
+            q->setDigit(j, qhat);
+    }
+
+    if (quotient != nullptr) {
+        // Caller will right-trim.
+        *quotient = q;
+    }
+
+    if (remainder != nullptr) {
+        u->inplaceRightShift(shift);
+        *remainder = u;
+    }
+}
+
+// Returns whether (factor1 * factor2) > (high << kDigitBits) + low.
+inline bool JSBigInt::productGreaterThan(Digit factor1, Digit factor2, Digit high, Digit low)
+{
+    Digit resultHigh;
+    Digit resultLow = digitMul(factor1, factor2, resultHigh);
+    return resultHigh > high || (resultHigh == high && resultLow > low);
+}
+
+// Adds {summand} onto {this}, starting with {summand}'s 0th digit
+// at {this}'s {startIndex}'th digit. Returns the "carry" (0 or 1).
+JSBigInt::Digit JSBigInt::absoluteInplaceAdd(JSBigInt* summand, unsigned startIndex)
+{
+    Digit carry = 0;
+    unsigned n = summand->length();
+    ASSERT(length() >= startIndex + n);
+    for (unsigned i = 0; i < n; i++) {
+        Digit newCarry = 0;
+        Digit sum = digitAdd(digit(startIndex + i), summand->digit(i), newCarry);
+        sum = digitAdd(sum, carry, newCarry);
+        setDigit(startIndex + i, sum);
+        carry = newCarry;
+    }
+
+    return carry;
+}
+
+// Subtracts {subtrahend} from {this}, starting with {subtrahend}'s 0th digit
+// at {this}'s {startIndex}-th digit. Returns the "borrow" (0 or 1).
+JSBigInt::Digit JSBigInt::absoluteInplaceSub(JSBigInt* subtrahend, unsigned startIndex)
+{
+    Digit borrow = 0;
+    unsigned n = subtrahend->length();
+    ASSERT(length() >= startIndex + n);
+    for (unsigned i = 0; i < n; i++) {
+        Digit newBorrow = 0;
+        Digit difference = digitSub(digit(startIndex + i), subtrahend->digit(i), newBorrow);
+        difference = digitSub(difference, borrow, newBorrow);
+        setDigit(startIndex + i, difference);
+        borrow = newBorrow;
+    }
+
+    return borrow;
+}
+
+void JSBigInt::inplaceRightShift(unsigned shift)
+{
+    ASSERT(shift < digitBits);
+    ASSERT(!(digit(0) & ((static_cast<Digit>(1) << shift) - 1)));
+
+    if (!shift)
+        return;
+
+    Digit carry = digit(0) >> shift;
+    unsigned last = length() - 1;
+    for (unsigned i = 0; i < last; i++) {
+        Digit d = digit(i + 1);
+        setDigit(i, (d << (digitBits - shift)) | carry);
+        carry = d >> shift;
+    }
+    setDigit(last, carry);
+}
+
+// Always copies the input, even when {shift} == 0.
+JSBigInt* JSBigInt::absoluteLeftShiftAlwaysCopy(VM& vm, JSBigInt* x, unsigned shift, LeftShiftMode mode)
+{
+    ASSERT(shift < digitBits);
+    ASSERT(!x->isZero());
+
+    unsigned n = x->length();
+    unsigned resultLength = mode == LeftShiftMode::AlwaysAddOneDigit ? n + 1 : n;
+    JSBigInt* result = createWithLength(vm, resultLength);
+
+    if (!shift) {
+        for (unsigned i = 0; i < n; i++)
+            result->setDigit(i, x->digit(i));
+        if (mode == LeftShiftMode::AlwaysAddOneDigit)
+            result->setDigit(n, 0);
+
+        return result;
+    }
+
+    Digit carry = 0;
+    for (unsigned i = 0; i < n; i++) {
+        Digit d = x->digit(i);
+        result->setDigit(i, (d << shift) | carry);
+        carry = d >> (digitBits - shift);
+    }
+
+    if (mode == LeftShiftMode::AlwaysAddOneDigit)
+        result->setDigit(n, carry);
+    else {
+        ASSERT(mode == LeftShiftMode::SameSizeResult);
+        ASSERT(!carry);
+    }
+
+    return result;
 }
 
@@ -605 +879 @@
 }
 
-String JSBigInt::toStringGeneric(ExecState& state, JSBigInt* x, unsigned radix)
+String JSBigInt::toStringGeneric(ExecState* state, JSBigInt* x, unsigned radix)
 {
     // FIXME: [JSC] Revisit usage of Vector into JSBigInt::toString
@@ -611 +885 @@
     Vector<LChar> resultString;
 
+    VM& vm = state->vm();
+
     ASSERT(radix >= 2 && radix <= 36);
     ASSERT(!x->isZero());
@@ -621 +897 @@
 
     if (maximumCharactersRequired > JSString::MaxLength) {
-        auto scope = DECLARE_THROW_SCOPE(state.vm());
-        throwOutOfMemoryError(&state, scope);
+        auto scope = DECLARE_THROW_SCOPE(vm);
+        throwOutOfMemoryError(state, scope);
         return String();
     }
@@ -647 +923 @@
         do {
             Digit chunk;
-            absoluteDivSmall(state, *dividend, chunkDivisor, &rest, chunk);
+            absoluteDivWithDigitDivisor(vm, *dividend, chunkDivisor, &rest, chunk);
             ASSERT(rest);
 
@@ -695 +971 @@
         return this;
 
-    ASSERT(m_length);
-
-    int nonZeroIndex = m_length - 1;
-    while (nonZeroIndex >= 0 && !digit(nonZeroIndex))
+    unsigned nonZeroIndex = m_length - 1;
+    while (!digit(nonZeroIndex))
         nonZeroIndex--;
 
-    if (nonZeroIndex == static_cast<int>(m_length - 1))
+    if (nonZeroIndex == m_length - 1)
         return this;
 
@@ -875 +1149 @@
 }
 
-JSBigInt::Digit JSBigInt::digit(unsigned n)
-{
-    ASSERT(n >= 0 && n < length());
+inline JSBigInt::Digit JSBigInt::digit(unsigned n)
+{
+    ASSERT(n < length());
     return dataStorage()[n];
 }
 
-void JSBigInt::setDigit(unsigned n, Digit value)
-{
-    ASSERT(n >= 0 && n < length());
+inline void JSBigInt::setDigit(unsigned n, Digit value)
+{
+    ASSERT(n < length());
     dataStorage()[n] = value;
 }

trunk/Source/JavaScriptCore/runtime/JSBigInt.h

@@ -83 +83 @@
 
     std::optional<uint8_t> singleDigitValueForString();
-    String toString(ExecState&, unsigned radix);
+    String toString(ExecState*, unsigned radix);
     
     JS_EXPORT_PRIVATE static bool equals(JSBigInt*, JSBigInt*);
@@ -95 +95 @@
     static JSBigInt* multiply(ExecState*, JSBigInt* x, JSBigInt* y);
     
+    static JSBigInt* divide(ExecState*, JSBigInt* x, JSBigInt* y);
+    static JSBigInt* unaryMinus(VM&, JSBigInt* x);
+    
 private:
 
-    enum ComparisonResult {
+    enum class ComparisonResult {
         Equal,
         Undefined,
@@ -119 +122 @@
     static uint64_t calculateMaximumCharactersRequired(unsigned length, unsigned radix, Digit lastDigit, bool sign);
     
-    static void absoluteDivSmall(ExecState&, JSBigInt* x, Digit divisor, JSBigInt** quotient, Digit& remainder);
+    static ComparisonResult absoluteCompare(JSBigInt* x, JSBigInt* y);
+    static void absoluteDivWithDigitDivisor(VM&, JSBigInt* x, Digit divisor, JSBigInt** quotient, Digit& remainder);
     static void internalMultiplyAdd(JSBigInt* source, Digit factor, Digit summand, unsigned, JSBigInt* result);
     static void multiplyAccumulate(JSBigInt* multiplicand, Digit multiplier, JSBigInt* accumulator, unsigned accumulatorIndex);
+    static void absoluteDivWithBigIntDivisor(VM&, JSBigInt* dividend, JSBigInt* divisor, JSBigInt** quotient, JSBigInt** remainder);
+    
+    enum class LeftShiftMode {
+        SameSizeResult,
+        AlwaysAddOneDigit
+    };
+    
+    static JSBigInt* absoluteLeftShiftAlwaysCopy(VM&, JSBigInt* x, unsigned shift, LeftShiftMode);
+    static bool productGreaterThan(Digit factor1, Digit factor2, Digit high, Digit low);
+
+    Digit absoluteInplaceAdd(JSBigInt* summand, unsigned startIndex);
+    Digit absoluteInplaceSub(JSBigInt* subtrahend, unsigned startIndex);
+    void inplaceRightShift(unsigned shift);
 
     // Digit arithmetic helpers.
@@ -130 +147 @@
     static Digit digitPow(Digit base, Digit exponent);
 
-    static String toStringGeneric(ExecState&, JSBigInt*, unsigned radix);
+    static String toStringGeneric(ExecState*, JSBigInt*, unsigned radix);
 
     bool isZero();
@@ -144 +161 @@
     static JSBigInt* allocateFor(ExecState*, VM&, unsigned radix, unsigned charcount);
 
+    static JSBigInt* copy(VM&, JSBigInt* x);
     JSBigInt* rightTrim(VM&);
 

trunk/Source/JavaScriptCore/runtime/JSCJSValue.cpp

@@ -383 +383 @@
         if (auto digit = bigInt->singleDigitValueForString())
             return vm.smallStrings.singleCharacterString(*digit + '0');
-        JSString* returnString = jsNontrivialString(&vm, bigInt->toString(*exec, 10));
+        JSString* returnString = jsNontrivialString(&vm, bigInt->toString(exec, 10));
         RETURN_IF_EXCEPTION(scope, errorValue());
         return returnString;