Guarded Devirtualization in CoreCLR
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coreclr
Languages & Compilers2015–2025
dotnet / coreclr · Archived
coreclr
CoreCLR is the runtime for .NET Core. It includes the garbage collector, JIT compiler, primitive data types and low-level classes.
97Distinct people
137Mentions
2Explicit recommenders
12.8KGitHub stars
What to know before exploring
What it is
CoreCLR is the runtime for .NET Core. It includes the garbage collector, JIT compiler, primitive data types and low-level classes.
GitHub
Where it is used
No documented product use was verified in the last source check.
What people are saying
> ... is one of my favorite side effects of it being open sourced. Agree! I would never have the time or expertise to work all this out just using WinDBG or similar. Having the…
matthewwarren used a recommendation phrase. 2 indexed comments match. This is a phrase match, not a verdict.
No classified warning is attached to this page. Read the discussions before treating silence as approval.
Also in these discussions
- dotnet/corefx · linked in 7 of the same discussions
- dotnet/roslyn · linked in 4 of the same discussions
- aspnet/mvc · linked in 2 of the same discussions
Mentioned in the same Hacker News threads. That is not proof they are substitutes.
This week on Hacker News
Nov 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 1:03:20 AM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by year137 dated mentions
Observed mentions: 2015-02-03 18:07:42 UTC to 2025-04-14 18:28:02 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2015 | 2015-01-01 00:00:00 UTC | 2016-01-01 00:00:00 UTC | 44 | 6 | 38 |
| 2016 | 2016-01-01 00:00:00 UTC | 2017-01-01 00:00:00 UTC | 23 | 3 | 20 |
| 2017 | 2017-01-01 00:00:00 UTC | 2018-01-01 00:00:00 UTC | 24 | 5 | 19 |
| 2018 | 2018-01-01 00:00:00 UTC | 2019-01-01 00:00:00 UTC | 17 | 3 | 14 |
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 23 | 3 | 20 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 3 | 0 | 3 |
| 2021 | 2021-01-01 00:00:00 UTC | 2022-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2022 | 2022-01-01 00:00:00 UTC | 2023-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2024 | 2024-01-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2025 | 2025-01-01 00:00:00 UTC | 2026-01-01 00:00:00 UTC | 1 | 0 | 1 |
From the project README
An excerpt from the repository, fetched Nov 13, 2026.
Read the project’s introduction
Going forward, the .NET team is using https://github.com/dotnet/runtime to
develop the code and issues formerly in this repository.
Please see the following for more context:
dotnet/announcements#119 "Consolidating .NET GitHub repos"
Read the full README on GitHubWhat Hacker News says
17 sourcesThe problem with .NET Core compared to Java is that it's still less portable at the moment - it doesn't work on any of the BSDs, for example. Someone's working on it, though.
https://github.com/dotnet/coreclr/issues/18067
In Announcing .NET Foundation Open MembershipDeep knowledge in a framework's code is unnecessary if you want to contribute
1 points · Open discussionPerformance Tracing .NET Core on Linux
1 points · Open discussionSpan<T> only requires .NET Standard 1.0, so it came out for Core and Framework at the same time [1].
.NET Framework only has the portable implementation though. The fast implementation requires support in the runtime, and Framework may never support fast Span<T> [2].
[1] https://www.nuget.org/packages/System.Memory/4.4.0-preview1-...
[2] https://github.com/dotnet/coreclr/issues/18280#issuecomment-...
In ASP.NET Core 3.0 will only run on .NET Corechar ref (managed pointer) is cast to byte ref https://github.com/dotnet/coreclr/blob/04d9b557ef8b7c60a1194...
Then it uses SpanHelpers.SequenceEqual for byte which is vectorized
https://github.com/dotnet/coreclr/blob/04d9b557ef8b7c60a1194...
In Bing.com now runs on .NET CoreThe first commit says "Vectorization of string.Equals". It now uses SpanHelpers.SequenceEqual. How is that vectorized when it's just an unrolled loop from what I see? Does vectorization not mean using SIMD instructions? It also means improving data dependencies?
https://github.com/dotnet/coreclr/blob/48cb3fa29a63219a9669a...
In Bing.com now runs on .NET CoreAnother exciting development in moving beyond UTF-16: Microsoft is experimenting with adding a native UTF-8 string in .NET next to the existing UTF-16 string:
https://github.com/dotnet/coreclr/commits/feature/utf8string
In Introducing the Windows Pseudo Console (ConPty)> - .NET is "multiplatform", but clearly second-class in terms of tooling and perf on non-windows platforms.
I agree, and we found this out recently the hard way.
For example, the CoreCLR does NOT build on 32-bit Linux as of now [1]. While our software has absolutely no reason to complain (and doesn't on Windows!), we can't target 32-bit Linux users.
[1]: https://github.com/dotnet/coreclr/issues/9265
In Where did the Microsoft tech stack disappear?That's garbled in several ways I'm afraid.
Firstly type erasure and escape analysis are un-related. Whether an object escapes or not is unrelated to things like whether it's a List<Integer> or List<int>.
Secondly .NET doesn't do escape analysis at all:
https://github.com/dotnet/coreclr/issues/1784
Thirdly HotSpot will happily escape analyze and then scalar replace regular objects, it isn't limited to ints and floats. It can make a big difference in many situations.
Fourthly and finally, if it were "easy to see where data escapes" in Go there wouldn't need to be tools to help the programmer find out, and Go developers wouldn't spend time manually tweaking to try and ensure the optimisation works.
In Getting to Go: Garbage collection and runtime issues> ... is one of my favorite side effects of it being open sourced.
Agree!
I would never have the time or expertise to work all this out just using WinDBG or similar. Having the source, including decent comments and things like the BOTR [0] is amazing for exploring the internals!
[0]: https://github.com/dotnet/coreclr/tree/master/Documentation/...
In .NET JIT and CLR – Joined at the HipMuch of the context is in dotnet/coreclr #13388 [1].
At the risk of repeating the content of the blog post ... The issue was reported in August, 2017 and fixed later in the same month. The fix shipped in a .NET Core patch update in September. We attempted to get the fix into .NET Framework 4.7.2 but missed that scheduling. We're now looking at making the fix in a .NET Framework patch release.
[1] https://github.com/dotnet/coreclr/issues/13388
In Why Skylake CPUs Are Sometimes 50% SlowerIt's very frustrating having all of these tools only support Windows.
Despite all the wonderful work Microsoft has done with CoreCLR, the "IDE" debugger is still only available under a license that only permits use with Visual Studio and VSCode [1] and mdbg is still nowhere to be found for CoreCLR [2].
1: https://github.com/dotnet/core/issues/505
2: https://github.com/dotnet/coreclr/issues/1145
From what I've gathered, the best you have right now for doing command line debugging is the "SOS" plugin for lldb, which seems to require building the lldb plugin and sometimes even lldb (!!) yourself [3][4].
3: https://github.com/dotnet/coreclr/blob/master/Documentation/...
4: http://blogs.microsoft.co.il/sasha/2017/02/26/analyzing-a-ne...
Not very fun if you're not using Windows.
In Tools for Exploring .NET InternalsYeah, that's what impressed me as well!
Turns out that even more components could be written in C#, but the ROI just isn't worth it, see https://github.com/dotnet/coreclr/issues/17576 for an interesting discussion
In CoreRT – A .NET Runtime for AOTAs part of Google Summer of Code a participant is looking at porting .net core to FreeBSD https://github.com/dotnet/coreclr/issues/18067
In Announcing .NET Core 2.1Showing the 15 most recent of 17 sources. Enable JavaScript to search and browse every indexed mention.