nop

It's not a big secret that x86 (and x86_64) processors have not only the single-byte NOP instruction, but also various types of multi-byte NOP-like instructions. There's the ones I've managed to find: Recommended by AMD, ref. AMD Software Optimization Guide for AMD Family 15h Processors, document #47414 , section 5.8 "Code Padding with Operand-Size Override and Multibyte NOP", page 94) 90 NOP1_OVERRIDE_NOP 6690 NOP2_OVERRIDE_NOP 0f1f00 NOP3_OVERRIDE_NOP 0f1f4000 NOP4_OVERRIDE_NOP 0f1f440000 NOP5_OVERRIDE_NOP 660f1f440000 NOP6_OVERRIDE_NOP 0f1f8000000000 NOP7_OVERRIDE_NOP 0f1f840000000000 NOP8

I was trawling through some of the IL of one of my assemblies (via ILDasm) and I noticed that all of my methods begin with a nop instruction. Does anyone know why that is? The assembly was compiled in debug mode. Nop instructions do not do anything (i.e have no side effects), but act as a convenient instruction to place a breakpoint. Tip If you need a place for an additional breakpoint for debugging purposes, you can force the inclusion of a Nop in a Debug build by adding a pair of empty braces, e.g. _grid.PreviewMouseRightButtonDown += (sender, e) => { _isRightMouseDown = true; RowColumnIndex