Methods are not getting inlined

[bugproof]

Why DecimalExtensions:Round is not getting inlined? I followed instructions here https://github.com/dotnet/coreclr/blob/master/Documentation/building/viewing-jit-dumps.md to get the jit dump. I published the program in release. As you can see it still calls DecimalExtensions:Round instead of calling Decimal:Round directly.

using System;
using System.Runtime.CompilerServices;

public static class DecimalExtensions
{
    [MethodImpl(MethodImplOptions.AggressiveInlining)] // doesn't help
    public static decimal Round(this decimal @this)
    {
        return decimal.Round(@this);
    }
}

public static class Program
{
    public static void Main()
    {
        Console.WriteLine(1.2134m.Round());
        Console.WriteLine(decimal.Round(1.2134m));
    }
}

The dump:

G_M20519_IG01:        ; func=00, offs=000000H, size=0013H, gcrefRegs=00000000 {}, byrefRegs=00000000 {}, byref, nogc <-- Prolog IG

IN002e: 000000 push     rbp
IN002f: 000001 sub      rsp, 192
IN0030: 000008 vzeroupper
IN0031: 00000B lea      rbp, [rsp+C0H]

G_M20519_IG02:        ; offs=000013H, size=00D3H, gcrefRegs=00000000 {}, byrefRegs=00000000 {}, byref

IN0001: 000013 lea      rcx, bword ptr [V01 rbp-10H]
IN0002: 000017 vxorps   xmm0, xmm0
IN0003: 00001C vmovdqu  qword ptr [rcx], xmm0
IN0004: 000021 xor      ecx, ecx
IN0005: 000023 mov      dword ptr [V00+0x20 rsp+20H], ecx
IN0006: 000027 mov      dword ptr [V00+0x28 rsp+28H], 4
IN0007: 00002F lea      rcx, bword ptr [V01 rbp-10H]
IN0008: 000033 mov      edx, 0x2F66
IN0009: 000038 xor      r8d, r8d
IN000a: 00003B xor      r9d, r9d
IN000b: 00003E call     Decimal:.ctor(int,int,int,bool,ubyte):this
IN000c: 000043 lea      rcx, bword ptr [V02 rbp-20H]
IN000d: 000047 mov      qword ptr [V06 rbp-58H], rcx
IN000e: 00004B vmovdqu  xmm0, qword ptr [V01 rbp-10H]
IN000f: 000051 vmovdqu  qword ptr [V05 rbp-50H], xmm0
IN0010: 000057 mov      rcx, qword ptr [V06 rbp-58H]
IN0011: 00005B lea      rdx, bword ptr [V05 rbp-50H]
IN0012: 00005F call     DecimalExtensions:Round(struct):struct
IN0013: 000064 vmovdqu  xmm0, qword ptr [V02 rbp-20H]
IN0014: 00006A vmovdqu  qword ptr [V07 rbp-68H], xmm0
IN0015: 000070 lea      rcx, bword ptr [V07 rbp-68H]
IN0016: 000074 call     Console:WriteLine(struct)
IN0017: 000079 lea      rcx, bword ptr [V03 rbp-30H]
IN0018: 00007D vxorps   xmm0, xmm0
IN0019: 000082 vmovdqu  qword ptr [rcx], xmm0
IN001a: 000087 xor      ecx, ecx
IN001b: 000089 mov      dword ptr [V00+0x20 rsp+20H], ecx
IN001c: 00008D mov      dword ptr [V00+0x28 rsp+28H], 4
IN001d: 000095 lea      rcx, bword ptr [V03 rbp-30H]
IN001e: 000099 mov      edx, 0x2F66
IN001f: 00009E xor      r8d, r8d
IN0020: 0000A1 xor      r9d, r9d
IN0021: 0000A4 call     Decimal:.ctor(int,int,int,bool,ubyte):this
IN0022: 0000A9 lea      rcx, bword ptr [V04 rbp-40H]
IN0023: 0000AD mov      qword ptr [V09 rbp-80H], rcx
IN0024: 0000B1 vmovdqu  xmm0, qword ptr [V03 rbp-30H]
IN0025: 0000B7 vmovdqu  qword ptr [V08 rbp-78H], xmm0
IN0026: 0000BD mov      rcx, qword ptr [V09 rbp-80H]
IN0027: 0000C1 lea      rdx, bword ptr [V08 rbp-78H]
IN0028: 0000C5 call     Decimal:Round(struct):struct
IN0029: 0000CA vmovdqu  xmm0, qword ptr [V04 rbp-40H]
IN002a: 0000D0 vmovdqu  qword ptr [V10 rbp-90H], xmm0
IN002b: 0000D9 lea      rcx, bword ptr [V10 rbp-90H]
IN002c: 0000E0 call     Console:WriteLine(struct)
IN002d: 0000E5 nop

G_M20519_IG03:        ; offs=0000E6H, size=0006H, epilog, nogc, emitadd

IN0032: 0000E6 lea      rsp, [rbp]
IN0033: 0000EA pop      rbp
IN0034: 0000EB ret

[benaadams]

Try setting the environment variable

set COMPlus_JitPrintInlinedMethods=1

Should give more info?

[bugproof]

With COMPlus_JitPrintInlinedMethods=1:

****** DONE compiling Program:Main()
**************** Inline Tree
Inlines into 06000000 DomainBoundILStubClass:IL_STUB_PInvoke(int):long
  [0 IL=0010 TR=000011 060030F5] [FAILED: noinline per IL/cached result] StubHelpers:ClearLastError()
  [0 IL=0030 TR=000025 060030F6] [FAILED: noinline per IL/cached result] StubHelpers:SetLastError()
Budget: initialTime=192, finalTime=192, initialBudget=1920, currentBudget=1920
Budget: initialSize=1134, finalSize=1134
**************** Inline Tree
Inlines into 06000000 DomainBoundILStubClass:IL_STUB_PInvoke(long,long,int,byref,long):int
  [0 IL=0035 TR=000031 060030F5] [FAILED: noinline per IL/cached result] StubHelpers:ClearLastError()
  [0 IL=0055 TR=000049 060030F6] [FAILED: noinline per IL/cached result] StubHelpers:SetLastError()
Budget: initialTime=303, finalTime=303, initialBudget=3030, currentBudget=3030
Budget: initialSize=1978, finalSize=1978
**************** Inline Tree
Inlines into 06000000 DomainBoundILStubClass:IL_STUB_PInvoke():int
  [0 IL=0004 TR=000005 060030F5] [FAILED: noinline per IL/cached result] StubHelpers:ClearLastError()
  [0 IL=0024 TR=000018 060030F6] [FAILED: noinline per IL/cached result] StubHelpers:SetLastError()
Budget: initialTime=168, finalTime=168, initialBudget=1680, currentBudget=1680
Budget: initialSize=952, finalSize=952
**************** Inline Tree
Inlines into 06000000 DomainBoundILStubClass:IL_STUB_PInvoke(long):int
  [0 IL=0009 TR=000010 060030F5] [FAILED: noinline per IL/cached result] StubHelpers:ClearLastError()
  [0 IL=0029 TR=000024 060030F6] [FAILED: noinline per IL/cached result] StubHelpers:SetLastError()
Budget: initialTime=189, finalTime=189, initialBudget=1890, currentBudget=1890
Budget: initialSize=1111, finalSize=1111
**************** Inline Tree
Inlines into 06000000 DomainBoundILStubClass:IL_STUB_PInvoke(int,int,long,int,long,int,long,long):int
Budget: initialTime=372, finalTime=372, initialBudget=3720, currentBudget=3720
Budget: initialSize=2502, finalSize=2502

[benaadams]

Guessing is with Core 2.2+; likely to be teired jitting? Try switching it off

COMPlus_TieredCompilation=0

Method needs to be called 10 times I think to recompile with inlining active with tiered Jit I believe

[bugproof]

@benadams with tiered jitting switched off it seems to inline correctly, however, it's not listed when using COMPlus_JitPrintInlinedMethods=1 ( the output of inlined methods doesn't change)

[benaadams]

With teiring enabled then it should inline on the 11th iteration of

public static void Run()
{
    Console.WriteLine(1.2134m.Round());
    Console.WriteLine(decimal.Round(1.2134m));
}

public static void Main()
{
    for (var i = 0; i < 20; i++)
    {
        Run();
    }
}

[AndyAyersMS]

Also make sure you are copying a check or debug built JIT into a release build of the runtime/framework.

The debug build of the System.Private.CoreLib will have an attribute that inhibits all jit optimization. The checked build will still contain assertion checks.

[RussKeldorph]

@Necronux Is this issue answered to your satisfaction? Can you close?