Remove wasteful virtuals according to SizeBench #11889

lhecker · 2021-12-07T02:46:17Z

This commit removes some pure virtual base classes from conhost,
found with the help of SizeBench. This reduces binary size by 5kB.
The reduction in code size however is the main benefit of this.

Additionally this fixes a mysterious, undebuggable crash in
~RenderThread(), caused by a Control Flow Guard failure when
the class was destroyed over its IRenderThread interface.

PR Checklist

I work here
Tests added/passed

Validation Steps Performed

Printing text works ✅
Printing VT works ✅
Performance is alright ✅

lhecker · 2021-12-07T02:51:43Z

@miniksa Some of these removals might be bad. Can you check which one's I need to revert?

For instance this pulls in interactivity/win32 code into interactivity/base and that's kinda whack.

On the other hand some of these changes actually make sense once you check neighboring code. For example, SetTerminalOwner(ITerminalOwner*) was changed to SetTerminalOwner(VtIo*) and that sounds weird right? Until you realize that the function in question is called VtEngine::SetTerminalOwner and suddenly it kinda makes sense.
~~(Also this PR removes almost a metric ton of code (literally actually, because it removes almost 1000 lines lol), so that's also nice.)~~

So... yeah. Just let me know what to revert and I'll do that. No hard feelings. The IRenderThread removal is the only thing that'd I'd like to really-really merge.

src/interactivity/base/InteractivityFactory.hpp

miniksa

do I have hidden pending comments

EDIT: no it lost them somewhere damn it

src/server/ApiMessage.h

src/host/_stream.cpp

miniksa

65/65. I think I called out the important bits.

zadjii-msft

I'm okay with this. I really liked how we used to have all these neat little silos that didn't know about the impl details of other parts of the codebase. But, I get that it's bad for performance, and we never really leveraged that siloing, so 🤷

zadjii-msft · 2021-12-15T11:37:00Z

src/renderer/inc/IRenderEngine.hpp

@@ -31,7 +31,7 @@ namespace Microsoft::Console::Render
        std::optional<CursorOptions> cursorInfo;
    };

-    class IRenderEngine
+    class __declspec(novtable) IRenderEngine


Should we have been doing this just always? I literally had no idea this existed, but seems really valuable for interfaces

Yeah, we probably should ;P

zadjii-msft

wait I'm dismissing my own review since this still doesn't build yet, wanna make sure the headers don't get included in a totally bonkers fashion

lhecker · 2021-12-15T23:18:56Z

I fixed the compilation error btw. 🙂

DHowett

I wish we could have the value of an interface (SPECIFICALLY: the restriction on what somebody holding a pointer can do. I don't care about swapping the impementation) without the cost.

DHowett · 2021-12-16T23:07:01Z

src/renderer/inc/IRenderEngine.hpp

@@ -31,7 +31,7 @@ namespace Microsoft::Console::Render
        std::optional<CursorOptions> cursorInfo;
    };

-    class IRenderEngine
+    class __declspec(novtable) IRenderEngine


Yeah, we probably should ;P

DHowett · 2021-12-16T23:08:02Z

src/renderer/vt/vtrenderer.hpp

@@ -15,13 +15,13 @@ Author(s):

 #pragma once

+#include <../host/VtIo.hpp>


I know you've explained that these don't matter to this specific compiler, but I do think we should follow the prevailing style!

That is: "".

Actually this is even worse! This file is src/renderer/vt/vtrenderer.hpp and I'm trying to include src/host/VtIo.hpp.

With "" this would then be a MS specific search path, because MSVC is the only compiler which allows "" includes to search in the current directories of previously included files. I've replaced it with "../../host/VtIo.hpp".

DHowett · 2021-12-16T23:08:23Z

src/renderer/vt/vtrenderer.hpp

@@ -31,9 +31,14 @@ namespace TerminalCoreUnitTests
 };
 #endif

+namespace Microsoft::Console::VirtualTerminal
+{
+    class VtIo;


You included the header and forward-declared VtIo?

DHowett · 2021-12-16T23:11:07Z

Also this PR removes almost a metric ton of code (literally actually, because it removes almost 1000 lines lol), so that's also nice.

Given that we are not making as extensive of changes as we were when you wrote this, are we still saving a whole 10kb?

lhecker · 2021-12-16T23:23:35Z

I wish we could have the value of an interface (SPECIFICALLY: the restriction on what somebody holding a pointer can do. I don't care about swapping the impementation) without the cost.

Honestly, I feel like we can still do that. I just personally feel like we don't necessarily need to keep interfaces if no one has been using them for years. This makes it very unlikely anyone will make use of them in the next years either. If we need to turn any of these structs into an interface one day, it's likely easier to "interfacify" code than remove those interfaces, since at the point you "interfacify" them you already have the knowledge about the requirements of at least 2 implementations and not just the one for which it was originally written.

I'll fix the issues in a minute and go over the PR again.

ghost · 2022-01-07T17:55:38Z

Hello @DHowett!

Because this pull request has the AutoMerge label, I will be glad to assist with helping to merge this pull request once all check-in policies pass.

p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (`@msftbot`) and give me an instruction to get started! Learn more here.

ghost · 2022-02-03T18:24:27Z

🎉Windows Terminal Preview v1.13.10336.0 has been released which incorporates this pull request.:tada:

Handy links:

lhecker requested a review from miniksa December 7, 2021 02:46

lhecker force-pushed the dev/lhecker/remove-wasteful-virtuals branch from 2f0ff80 to f42c8fc Compare December 7, 2021 15:26

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lhecker added this to the Engineering Improvements 2021 milestone Dec 7, 2021

lhecker force-pushed the dev/lhecker/remove-wasteful-virtuals branch from 07c82d3 to e352a45 Compare December 7, 2021 16:40

lhecker added Area-CodeHealth Issues related to code cleanliness, linting, rules, warnings, errors, static analysis, etc. Product-Conhost For issues in the Console codebase labels Dec 7, 2021

lhecker mentioned this pull request Dec 10, 2021

There's a weird crash(?) tearing down the Renderer? #11891

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miniksa reviewed Dec 10, 2021

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lhecker force-pushed the dev/lhecker/remove-wasteful-virtuals branch from e352a45 to 185064e Compare December 14, 2021 16:54

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lhecker force-pushed the dev/lhecker/remove-wasteful-virtuals branch from 185064e to 05ff1c0 Compare December 14, 2021 17:05

Remove wasteful virtuals according to SizeBench

cfab0f1

lhecker force-pushed the dev/lhecker/remove-wasteful-virtuals branch from 05ff1c0 to cfab0f1 Compare December 14, 2021 17:06

zadjii-msft approved these changes Dec 15, 2021

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ghost added the Needs-Author-Feedback The original author of the issue/PR needs to come back and respond to something label Dec 15, 2021

Fix compilation error

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ghost removed the Needs-Author-Feedback The original author of the issue/PR needs to come back and respond to something label Dec 15, 2021

lhecker marked this pull request as ready for review December 15, 2021 23:18

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ghost merged commit 825efda into main Jan 7, 2022

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Remove wasteful virtuals according to SizeBench #11889

Remove wasteful virtuals according to SizeBench #11889

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ghost commented Feb 3, 2022

		@@ -15,13 +15,13 @@ Author(s):

		#pragma once

		#include <../host/VtIo.hpp>

Remove wasteful virtuals according to SizeBench #11889

Remove wasteful virtuals according to SizeBench #11889

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lhecker commented Dec 7, 2021 • edited

PR Checklist

Validation Steps Performed

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p.s. you can customize the way I help with merging this pull request, such as holding this pull request until a specific person approves. Simply @mention me (`@msftbot`) and give me an instruction to get started! Learn more here.