Skip to content

Avoid an allocation in BigInteger.Parse("-2147483648") #104666

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
tannergooding merged 2 commits into from
Dec 4, 2024
Merged

Avoid an allocation in BigInteger.Parse("-2147483648") #104666

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
e9364f2
Avoid an allocation in BigInteger.Parse("-2147483648")
kzrnm Jul 9, 2024
410ee80
Merge branch 'main' into BigIntegerSmall
danmoseley Dec 2, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
17 changes: 12 additions & 5 deletions src/libraries/System.Runtime.Numerics/src/System/Numerics/BigInteger.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -511,16 +511,23 @@ internal BigInteger(ReadOnlySpan<uint> value, bool negative)
{
this = default;
}
else if (value.Length == 1 && value[0] < kuMaskHighBit)
else if (value.Length == 1)
{
// Values like (Int32.MaxValue+1) are stored as "0x80000000" and as such cannot be packed into _sign
_sign = negative ? -(int)value[0] : (int)value[0];
_bits = null;
if (_sign == int.MinValue)
if (value[0] < kuMaskHighBit)
{
_sign = negative ? -(int)value[0] : (int)value[0];
_bits = null;
}
else if (negative && value[0] == kuMaskHighBit)
{
// Although Int32.MinValue fits in _sign, we represent this case differently for negate
this = s_bnMinInt;
}
else
{
_sign = negative ? -1 : +1;
_bits = [value[0]];
}
}
else
{
Expand Down
21 changes: 17 additions & 4 deletions src/libraries/System.Runtime.Numerics/tests/BigInteger/parse.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -233,10 +233,23 @@ private static void VerifyDefaultParse(Random random)
// BasicTests
VerifyFailParseToString(null, typeof(ArgumentNullException));
VerifyFailParseToString(string.Empty, typeof(FormatException));
VerifyParseToString("0");
VerifyParseToString("000");
VerifyParseToString("1");
VerifyParseToString("001");

foreach (var value in new string[]
{
"0",
"000",
"1",
"001",
int.MaxValue.ToString(),
int.MinValue.ToString(),
long.MaxValue.ToString(),
long.MinValue.ToString(),
Int128.MaxValue.ToString(),
Int128.MinValue.ToString(),
})
{
VerifyParseToString(value);
}

// SimpleNumbers - Small
for (int i = 0; i < s_samples; i++)
Expand Down