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LibCrypto+LibJS: Move Power to method of {Unsigned,Signed}BigInteger

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Having it as a method instead of a free function is necessary for the
next commits and generally allows for optimizations that require deeper
access into the `UnsignedBigInteger` / `SignedBigInteger`.

Also restrict the exponent to 32 bits to avoid huge memory allocations.
This commit is contained in:
devgianlu 2025-04-26 11:17:32 +02:00 • committed by Jelle Raaijmakers
commit 5a4cfd05d0
Notes: github-actions[bot] 2025-05-23 09:58:36 +00:00
7 changed files with 53 additions and 46 deletions
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10
Libraries/LibJS/Runtime/Value.cpp
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@ -15,7 +15,6 @@
#include <AK/StringFloatingPointConversions.h>
#include <AK/Utf8View.h>
#include <LibCrypto/BigInt/SignedBigInteger.h>
#include <LibCrypto/NumberTheory/ModularFunctions.h>
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Accessor.h>
#include <LibJS/Runtime/Array.h>
@ -1599,7 +1598,7 @@ ThrowCompletionOr<Value> left_shift(VM& vm, Value lhs, Value rhs)
return vm.throw_completion<RangeError>(ErrorType::BigIntSizeExceeded);
// 6.1.6.2.9 BigInt::leftShift ( x, y ), https://tc39.es/ecma262/#sec-numeric-types-bigint-leftShift
auto multiplier_divisor = Crypto::SignedBigInteger { Crypto::NumberTheory::Power(Crypto::UnsignedBigInteger(2), rhs_bigint) };
auto multiplier_divisor = Crypto::SignedBigInteger { Crypto::UnsignedBigInteger(2).pow(rhs_bigint.to_u64()) };
// 1. If y < 0ℤ, then
if (rhs_numeric.as_bigint().big_integer().is_negative()) {
@ -2075,9 +2074,14 @@ ThrowCompletionOr<Value> exp(VM& vm, Value lhs, Value rhs)
// 1. If exponent < 0ℤ, throw a RangeError exception.
if (exponent.is_negative())
return vm.throw_completion<RangeError>(ErrorType::NegativeExponent);
// AD-HOC: Prevent allocating huge amounts of memory.
if (exponent.unsigned_value().byte_length() > sizeof(u32))
return vm.throw_completion<RangeError>(ErrorType::BigIntSizeExceeded);
// 2. If base is 0ℤ and exponent is 0ℤ, return 1ℤ.
// 3. Return the BigInt value that represents ℝ(base) raised to the power ℝ(exponent).
return BigInt::create(vm, Crypto::NumberTheory::Power(base, exponent));
return BigInt::create(vm, base.pow(exponent.to_u64()));
}
return vm.throw_completion<TypeError>(ErrorType::BigIntBadOperatorOtherType, "exponentiation");
}