I would like to ask if the first example is somehow slower than the second example.
Example 1: for, unsafe, unsafe, unsafe, etc
for (var i = 0; i < ...; i++) { unsafe { // ... } } Example 2: unsafe, for
unsafe { for (var i = 0; i < ...; i++) { // ... } } Nowhere in the documentation this aspect is being covered.
Question:
Can someone assume than the location of an unsafe code block does not affect performance ?
They produce the exact same IL code so no performance difference
nested: See on SharpLab
c#
using System; public class C { public void M() { var x = 0; for (var i = 0; i < 100; i++) { unsafe { x+=i; } } } } IL
.class private auto ansi '<Module>' { } // end of class <Module> .class public auto ansi beforefieldinit C extends [System.Private.CoreLib]System.Object { // Methods .method public hidebysig instance void M () cil managed { // Method begins at RVA 0x2050 // Code size 20 (0x14) .maxstack 2 .locals init ( [0] int32, [1] int32 ) IL_0000: ldc.i4.0 IL_0001: stloc.0 IL_0002: ldc.i4.0 IL_0003: stloc.1 // sequence point: hidden IL_0004: br.s IL_000e // loop start (head: IL_000e) IL_0006: ldloc.0 IL_0007: ldloc.1 IL_0008: add IL_0009: stloc.0 IL_000a: ldloc.1 IL_000b: ldc.i4.1 IL_000c: add IL_000d: stloc.1 IL_000e: ldloc.1 IL_000f: ldc.i4.s 100 IL_0011: blt.s IL_0006 // end loop IL_0013: ret } // end of method C::M .method public hidebysig specialname rtspecialname instance void .ctor () cil managed { // Method begins at RVA 0x2070 // Code size 7 (0x7) .maxstack 8 IL_0000: ldarg.0 IL_0001: call instance void [System.Private.CoreLib]System.Object::.ctor() IL_0006: ret } // end of method C::.ctor } // end of class C surrounding: See on SharpLab
c#
using System; public class C { public void M() { var x = 0; unsafe { for (var i = 0; i < 100; i++) { x+=i; } } } } IL
.class private auto ansi '<Module>' { } // end of class <Module> .class public auto ansi beforefieldinit C extends [System.Private.CoreLib]System.Object { // Methods .method public hidebysig instance void M () cil managed { // Method begins at RVA 0x2050 // Code size 20 (0x14) .maxstack 2 .locals init ( [0] int32, [1] int32 ) IL_0000: ldc.i4.0 IL_0001: stloc.0 IL_0002: ldc.i4.0 IL_0003: stloc.1 // sequence point: hidden IL_0004: br.s IL_000e // loop start (head: IL_000e) IL_0006: ldloc.0 IL_0007: ldloc.1 IL_0008: add IL_0009: stloc.0 IL_000a: ldloc.1 IL_000b: ldc.i4.1 IL_000c: add IL_000d: stloc.1 IL_000e: ldloc.1 IL_000f: ldc.i4.s 100 IL_0011: blt.s IL_0006 // end loop IL_0013: ret } // end of method C::M .method public hidebysig specialname rtspecialname instance void .ctor () cil managed { // Method begins at RVA 0x2070 // Code size 7 (0x7) .maxstack 8 IL_0000: ldarg.0 IL_0001: call instance void [System.Private.CoreLib]System.Object::.ctor() IL_0006: ret } // end of method C::.ctor } // end of class C 
