In the IL code produced, there are some lines missing. What task does the in between lines perform?

Question

.method private hidebysig static void  Main(string[] args) cil managed
{
  .entrypoint
  // Code size       9 (0x9)
  .maxstack  1
  .locals init ([0] class ConstReadOnly.second p)
  IL_0000:  nop
  IL_0001:  ldc.i4.5
  IL_0002:  newobj     instance void ConstReadOnly.second::.ctor(int32)
  IL_0007:  stloc.0
  IL_0008:  ret
} // end of method Program::Main

Here the IL_0002 is followed by IL_0007.
Can any one please give me the actual scenario happening here?

@Wiktor Zychla but my question is what are these inbetween lines performing and i have'nt got any clue there. — murali.j, Dec 29 '16 at 04:07

score 3 · Accepted Answer · answered Dec 27 '16 at 17:24

3

It's only labels. There's no code in between. The label represents offset from the beginning off the function in bytes.

offset_0:  nop      //size 1 byte
offset_1:  ldc.i4.5 // size 1 byte
offset_2:  newobj instance void ConstReadOnly.second::.ctor(int32) // size 5 bytes
offset_7:  stloc.0 // size 1 byte 
offset_8:  ret

You can easily change them and recompile again.

answered Dec 27 '16 at 17:24

Paweł Łukasik

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thanks @powel lukasik._can you suggest me how to track the execution of the lines of code in visual studio at memory allocation range. we can do debugging but gives no information about memory allocation._ – murali.j Dec 27 '16 at 17:35
@murali.j it's a bit unrelated to your original question. I don't think you can do that. There is a plugin to R# that shows hidden allocation - https://github.com/controlflow/resharper-heapview – Paweł Łukasik Dec 27 '16 at 17:37
lukasik yeah it is unrelated. but thanks for the information. – murali.j Dec 27 '16 at 18:10

score 1 · Answer 2 · answered Dec 28 '16 at 16:35

When I run ildasm on your code while specifying the /BYTES option, the output is:

.method private hidebysig static void  Main(string[] args) cil managed
// SIG: 00 01 01 1D 0E
{
  .entrypoint
  // Method begins at RVA 0x2048
  // Code size       9 (0x9)
  .maxstack  1
  .locals init (class ConstReadOnly.second V_0)
  IL_0000:  /* 00   |                  */ nop
  IL_0001:  /* 1B   |                  */ ldc.i4.5
  IL_0002:  /* 73   | (06)000003       */ newobj     instance void ConstReadOnly.second::.ctor(int32)
  IL_0007:  /* 0A   |                  */ stloc.0
  IL_0008:  /* 2A   |                  */ ret
} // end of method Program::Main

Here you can see the actual bytes used to represent your code on disk as comments. Notice that all instructions use just one byte, except for the newobj instruction, which is 5 bytes, which corresponds exactly to the numbers used in the line labels.

Those labels are there so that any jump instructions can show you where they jump. They don't have any relation to lines of code you wrote in C#.

In the IL code produced, there are some lines missing. What task does the in between lines perform?

2 Answers2