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[release/7.0] Ensure that the result for PowMod is fully initialized#74672

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Merged
carlossanlop merged 2 commits into from
Aug 28, 2022
Merged

[release/7.0] Ensure that the result for PowMod is fully initialized #74672

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4b39bb4
Adding a regression test for dotnet/performance#2575
tannergooding Aug 25, 2022
e565249
Ensure that the result span is fully initialized.
tannergooding Aug 25, 2022
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30 changes: 20 additions & 10 deletions src/libraries/System.Runtime.Numerics/src/System/Numerics/BigIntegerCalculator.PowMod.cs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -35,7 +35,9 @@ stackalloc uint[StackAllocThreshold]
value.CopyTo(valueCopy);
valueCopy.Slice(value.Length).Clear();

PowCore(valueCopy, value.Length, temp, power, bits).CopyTo(bits);
Span<uint> result = PowCore(valueCopy, value.Length, temp, power, bits);
result.CopyTo(bits);
bits.Slice(result.Length).Clear();

if (tempFromPool != null)
ArrayPool<uint>.Shared.Return(tempFromPool);
Expand All@@ -50,19 +52,19 @@ private static Span<uint> PowCore(Span<uint> value, int valueLength, Span<uint>
Debug.Assert(value.Length == temp.Length);

result[0] = 1;
int bitsLength = 1;
int resultLength = 1;

// The basic pow algorithm using square-and-multiply.
while (power != 0)
{
if ((power & 1) == 1)
bitsLength = MultiplySelf(ref result, bitsLength, value.Slice(0, valueLength), ref temp);
resultLength = MultiplySelf(ref result, resultLength, value.Slice(0, valueLength), ref temp);
if (power != 1)
valueLength = SquareSelf(ref value, valueLength, ref temp);
power >>= 1;
}

return result;
return result.Slice(0, resultLength);
}

private static int MultiplySelf(ref Span<uint> left, int leftLength, ReadOnlySpan<uint> right, ref Span<uint> temp)
Expand DownExpand Up@@ -313,7 +315,9 @@ private static void PowCore(Span<uint> value, int valueLength,

if (modulus.Length < ReducerThreshold)
{
PowCore(value, valueLength, power, modulus, bits, 1, temp).CopyTo(bits);
Span<uint> result = PowCore(value, valueLength, power, modulus, bits, 1, temp);
result.CopyTo(bits);
bits.Slice(result.Length).Clear();
}
else
{
Expand DownExpand Up@@ -349,7 +353,9 @@ stackalloc uint[StackAllocThreshold]
if (rFromPool != null)
ArrayPool<uint>.Shared.Return(rFromPool);

PowCore(value, valueLength, power, reducer, bits, 1, temp).CopyTo(bits);
Span<uint> result = PowCore(value, valueLength, power, reducer, bits, 1, temp);
result.CopyTo(bits);
bits.Slice(result.Length).Clear();

if (muFromPool != null)
ArrayPool<uint>.Shared.Return(muFromPool);
Expand All@@ -369,7 +375,9 @@ private static void PowCore(Span<uint> value, int valueLength,

if (modulus.Length < ReducerThreshold)
{
PowCore(value, valueLength, power, modulus, bits, 1, temp).CopyTo(bits);
Span<uint> result = PowCore(value, valueLength, power, modulus, bits, 1, temp);
result.CopyTo(bits);
bits.Slice(result.Length).Clear();
}
else
{
Expand DownExpand Up@@ -405,7 +413,9 @@ stackalloc uint[StackAllocThreshold]
if (rFromPool != null)
ArrayPool<uint>.Shared.Return(rFromPool);

PowCore(value, valueLength, power, reducer, bits, 1, temp).CopyTo(bits);
Span<uint> result = PowCore(value, valueLength, power, reducer, bits, 1, temp);
result.CopyTo(bits);
bits.Slice(result.Length).Clear();

if (muFromPool != null)
ArrayPool<uint>.Shared.Return(muFromPool);
Expand DownExpand Up@@ -472,7 +482,7 @@ private static Span<uint> PowCore(Span<uint> value, int valueLength,
power >>= 1;
}

return result;
return result.Slice(0, resultLength);
}

private static Span<uint> PowCore(Span<uint> value, int valueLength,
Expand DownExpand Up@@ -531,7 +541,7 @@ private static Span<uint> PowCore(Span<uint> value, int valueLength,
power >>= 1;
}

return result;
return result.Slice(0, resultLength);
}
}
}
15 changes: 14 additions & 1 deletion src/libraries/System.Runtime.Numerics/tests/BigInteger/modpow.cs
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Original file line numberDiff line numberDiff line change
Expand Up@@ -275,7 +275,7 @@ public static void ModPowAxiom()
}

[Fact]
public static void RegressionIssue70330()
public static void RegressionIssueRuntime70330()
{
byte[] tempByteArray1 = { 226, 32 };
byte[] tempByteArray2 = { 113 };
Expand All@@ -286,6 +286,19 @@ public static void RegressionIssue70330()
);
}

[Fact]
public static void RegressionIssuePerformance2575()
{
byte[] tempByteArray1 = { 0x93, 0x30, 0x70, 0xD8, 0x74, 0x0A, 0x70, 0x79, 0x18, 0x5A, 0xCD, 0x2D, 0x39, 0xBF, 0x36, 0xC6, 0x24, 0xDE, 0x4B, 0xD5, 0xC7, 0xB4, 0x56, 0x23, 0xB2, 0xB4, 0xB7, 0x43, 0xE5, 0x05, 0xDD, 0xAF, 0x97, 0x81, 0x67, 0xCB, 0x67, 0xE9, 0x53, 0x5A, 0x00, 0x42, 0x9B, 0x20, 0x56, 0xFA, 0xBE, 0x27, 0x6A, 0x14, 0x36, 0x17, 0x49, 0xC5, 0xAC, 0xDF, 0xDA, 0x4C, 0x26, 0xC0, 0x52, 0x2C, 0x93, 0x13, 0x7D, 0x1E, 0x96, 0xB8, 0x58, 0x6B, 0x5F, 0x3A, 0x8B, 0xF1, 0xD5, 0x84, 0x18, 0x36, 0xCC, 0xB7, 0xF5, 0x90, 0xD9, 0xD1, 0xCE, 0xC5, 0x65, 0xD2, 0xD5, 0x87, 0xF0, 0x1B, 0xC3, 0x92, 0x07, 0xD3, 0xAF, 0x88, 0xA2, 0x38, 0x64, 0x06, 0xCE, 0xFE, 0xB5, 0xFC, 0x8C, 0x58, 0xEF, 0x27, 0xC6, 0xA4, 0x7F, 0x6E, 0xCA, 0xC2, 0x53, 0xC2, 0x44, 0xB7, 0xB8, 0xC3, 0xE2, 0xD0, 0x7A, 0x43, 0x76, 0xF8, 0x00 };
byte[] tempByteArray2 = { 0x02, 0xD4, 0x90, 0x93, 0x94, 0x52, 0xEF, 0xC1, 0xDA, 0x1B, 0xD2, 0x39, 0x0D, 0xE3, 0xAD, 0xC1, 0x4C, 0x9B, 0x54, 0xC8, 0x44, 0x7F, 0xED, 0x43, 0xEA, 0x7F, 0xA1, 0x23, 0xFE, 0x84, 0x71, 0x85, 0x93, 0x6E, 0xEC, 0x53, 0x35, 0x10, 0xEB, 0x1C, 0xDA, 0x01, 0x78, 0xA6, 0x71, 0x7E, 0xAB, 0xE0, 0x35, 0x0F, 0x2E, 0xA8, 0x21, 0x30, 0xA5, 0x83, 0xE7, 0x4C, 0xA9, 0x14, 0xB0, 0xCC, 0xC3, 0x56, 0xAA, 0x4C, 0xA5, 0x9E, 0xF6, 0x5A, 0x8B, 0x3C, 0xAF, 0x38, 0xED, 0x43, 0x06, 0x46, 0xD2, 0x6C, 0xD3, 0xC1, 0xED, 0xEE, 0x55, 0xC8, 0x63, 0x63, 0xC9, 0x69, 0x6B, 0xE8, 0x67, 0xD6, 0x6B, 0x0D, 0x3E, 0x22, 0xFC, 0x24, 0xD8, 0x0C, 0xEA, 0xDB, 0x83, 0xF2, 0xF9, 0xE9, 0x43, 0x61, 0x7C, 0xA0, 0x7A, 0x3D, 0x41, 0xEF, 0xDF, 0xD4, 0x00, 0xE1, 0xE9, 0x42, 0xD5, 0x8C, 0xEE, 0xA3, 0xD5, 0xD8, 0x00 };
byte[] tempByteArray3 = { 0xDF, 0x05, 0xE4, 0x4A, 0xAD, 0x93, 0xC6, 0xD7, 0x00 };
byte[] tempByteArray4 = { 0xC6, 0x57, 0x30, 0x3F, 0xCE, 0x21, 0xA0, 0x3D };
VerifyIdentityString(
Print(tempByteArray3) + Print(tempByteArray2) + Print(tempByteArray1) + "tModPow",
Print(tempByteArray4)
);
}

[Fact]
public static void ModPowBoundary()
{
Expand Down