swiftlang/swift

[SR-6889] [IRGen Opportunity] Use argmemonly for runtime functions

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#49,438 opened on 2018年2月1日

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説明
Previous ID SR-6889
Radar None
Original Reporter @aschwaighofer
Type Improvement
Votes 0
Component/s Compiler
Labels Improvement, StarterBug
Assignee None
Priority Medium

md5: 050d922fc6f6b8f37d1f70d51229bf7b

Issue Description:

It should be possible to mark some of our runtime functions with argmemonly readonly as they receive their type arguments indirectly via an array of type arguments.

I tried this in https://github.com/apple/swift/pull/14310 but tests failed. I did not have time to investigate why.

I mentioned that if that following situation in some form or another this annotation is not legal:

Type *args[5];
pointer->field = // inlined initialization
arg[1] = pointer
argmemonly(args)

However, we believe that this situation should? not arise. It might be worth investigating the failures.

コントリビューターガイド

技術スタック
swiftcpp
領域
performance
Issue 種別
performance
難度新しい貢献者にとっての実装難度です。1 は非常に小さな変更、5 は専門的な作業です。
4
推定時間経験ある貢献者が調査、実装、テスト、pull request 準備にかけるおおよその時間範囲です。
3-5 days
活動状況Issue が今どれだけ取り組みやすいかを示します。新しい、活発、古い、ブロック中、またはメンテナー入力待ちなどです。
stale
明確さ期待される変更、受け入れ条件、次の手順がどれだけ明確かを示します。
needs investigation
前提条件
Understanding of LLVM IRFamiliarity with Swift runtime functionsKnowledge of C++
初心者向け度初回貢献者にどれだけ取り組みやすいかを 1-100 で推定したスコアです。
20
調査方針
Investigate why tests failed in the previous attempt (PR #14310). The key is to determine if the situation where 'argmemonly' is illegal can arise in the Swift runtime. Start by examining the runtime functions that receive type arguments indirectly via arrays. Look at the failing tests and understand the context. Check if there are any aliasing issues with the type arguments array. Possibly consult with maintainers or review related compiler code.