This appears to be a JIT bug; I’ve tested with:
// ... existing code unchanged
for (int i = 0; i < N - Old.Length; i++)
{
// Console.WriteLine(i); // <== comment/uncomment this line
dd[i] = d;
}
and adding the Console.WriteLine(i) fixes it. The only IL change is:
// ...
L_0040: ldc.i4.0
L_0041: stloc.3
L_0042: br.s L_004d
L_0044: ldarg.0
L_0045: ldind.ref
L_0046: ldloc.3
L_0047: ldloc.1
L_0048: stelem.r8
L_0049: ldloc.3
L_004a: ldc.i4.1
L_004b: add
L_004c: stloc.3
L_004d: ldloc.3
L_004e: ldarg.1
L_004f: ldloc.0
L_0050: ldlen
L_0051: conv.i4
L_0052: sub
L_0053: blt.s L_0044
L_0055: ret
vs
// ...
L_0040: ldc.i4.0
L_0041: stloc.3
L_0042: br.s L_0053
L_0044: ldloc.3
L_0045: call void [System.Console]System.Console::WriteLine(int32)
L_004a: ldarg.0
L_004b: ldind.ref
L_004c: ldloc.3
L_004d: ldloc.1
L_004e: stelem.r8
L_004f: ldloc.3
L_0050: ldc.i4.1
L_0051: add
L_0052: stloc.3
L_0053: ldloc.3
L_0054: ldarg.1
L_0055: ldloc.0
L_0056: ldlen
L_0057: conv.i4
L_0058: sub
L_0059: blt.s L_0044
L_005b: ret
which looks exactly right (the only difference is the extra ldloc.3 and call void [System.Console]System.Console::WriteLine(int32), and a different but equivalent target for br.s).
It’ll need a JIT fix, I suspect.
Environment:
Environment.Version: 4.0.30319.42000<TargetFramework>netcoreapp2.0</TargetFramework>- VS: 15.5.0 Preview 5.0
dotnet --version: 2.1.1