JIT doesn't inline methods contain EH code

[hez2010]

Description

JIT doesn't inline methods contain EH code.

Let's say this code:

void Test()
{
	Console.WriteLine(Foo(3));
}

int Foo(int x)
{
	try
	{
		return Get(x);
	}
	catch
	{
		return 0;
	}
}

int Get(int x) => x is 1 ? throw new Exception() : x + 1;

Expected codegen for Test:

mov	ecx, 4
jmp	System.Console.WriteLine(Int32)

Actual codegen for Test:

sub	rsp, 0x28
mov	ecx, 3
call	Program.Foo(Int32)
mov	ecx, eax
add	rsp, 0x28
jmp	System.Console.WriteLine(Int32)

Note that even I added [MethodImpl(MethodImplOptions.AggressiveInlining)] on top of the method Foo, it won't be inlined either.

Configuration

.NET 6

category:cq
theme:inlining
skill-level:expert
cost:medium
impact:medium

Tagging subscribers to this area: @JulieLeeMSFT
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

JIT doesn't inline methods contain EH code.

Let's say this code:

void Test()
{
	Console.WriteLine(Foo(3));
}

int Foo(int x)
{
	try
	{
		return Get(x);
	}
	catch
	{
		return 0;
	}
}

int Get(int x) => x is 1 ? throw new Exception() : x + 1;

Expected codegen for Test:

mov	ecx, 4
jmp	System.Console.WriteLine(Int32)

Actual codegen for Test:

sub	rsp, 0x28
mov	ecx, 3
call	Program.Foo(Int32)
mov	ecx, eax
add	rsp, 0x28
jmp	System.Console.WriteLine(Int32)

Note that even I added [MethodImpl(MethodImplOptions.AggressiveInlining)] on top of the method Foo, it won't be inlined either.

Configuration

.NET 6

Author:	hez2010
Assignees:	-
Labels:	tenet-performance, area-CodeGen-coreclr, untriaged
Milestone:	-

[AndyAyersMS]

This is a long-standing limitation in the jit, and non-trivial to fix.

If you know of examples in existing code bases where you think enabling this would be helpful, please point them out.

[MichalPetryka]

If you know of examples in existing code bases where you think enabling this would be helpful, please point them out.

The most impactful cases for this would probably be usings and foreaches (the latter would maybe then allow their devirtualization in more cases which would help stuff like LINQ).