Span<byte> from local variable bug in .net 7.x Release #89666
Description
Description
When using Span to map a local variable to an array, after a certain number of iterations, changing the local variable does not change the bytes in the Span
int value = 0;
Span<byte> span = MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref value, 1));
for (int i = 0; i < numEntries; i++)
{
//value = 0; bug fix for .net 7.x Release
value = random.Next();
file.Write(span);
}
Reproduction Steps
using System.Runtime.InteropServices;
#if DEBUG
string config = "Deb";
#else
string config = "Rel";
#endif
string template = "{0}.{1}.dat.{2}";
test(5000, 0);
test(5000, 1);
test(5000, 2);
cmp(0, 1);
cmp(0, 2);
cmp(1, 2);
void cmp(int fIdx, int sIdx)
{
byte[] f = File.ReadAllBytes(string.Format(template, config, Environment.Version, fIdx));
byte[] s = File.ReadAllBytes(string.Format(template, config, Environment.Version, sIdx));
for (int i = 0; i < f.Length; i++)
{
if (f[i] != s[i])
{
Console.WriteLine("first diff {0} ~ {1}, offset={2}, {3}/{4}", f[i], s[i], i, string.Format(template, config, Environment.Version, fIdx), string.Format(template, config, Environment.Version, sIdx));
return;
}
}
Console.WriteLine("{0}/{1} is equal", string.Format(template, config, Environment.Version, fIdx), string.Format(template, config, Environment.Version, sIdx));
}
void test(long numEntries, int idx)
{
Random random = new Random(1);
using var file = File.OpenWrite(string.Format(template, config, Environment.Version, idx));
file.SetLength(0);
int value = 0;
Span<byte> span = MemoryMarshal.AsBytes(MemoryMarshal.CreateSpan(ref value, 1));
for (int i = 0; i < numEntries; i++)
{
//value = 0; bug fix for .net 7.x Release
value = random.Next();
file.Write(span);
}
}
Expected behavior
all output files must be identical
Actual behavior
Results
first diff 15 ~ 222, offset=19996, Rel.7.0.9.dat.0/Rel.7.0.9.dat.1
first diff 96 ~ 241, offset=3996, Rel.7.0.9.dat.0/Rel.7.0.9.dat.2
first diff 96 ~ 241, offset=3996, Rel.7.0.9.dat.1/Rel.7.0.9.dat.2
Deb.7.0.9.dat.0/Deb.7.0.9.dat.1 is equal
Deb.7.0.9.dat.0/Deb.7.0.9.dat.2 is equal
Deb.7.0.9.dat.1/Deb.7.0.9.dat.2 is equal
Rel.6.0.20.dat.0/Rel.6.0.20.dat.1 is equal
Rel.6.0.20.dat.0/Rel.6.0.20.dat.2 is equal
Rel.6.0.20.dat.1/Rel.6.0.20.dat.2 is equal
Regression?
No response
Known Workarounds
No response
Configuration
.net 6.0.20
.net 7.0.9
Windows Server 2022
Other information
No response