[SR-6889] [IRGen Opportunity] Use argmemonly for runtime functions · swiftlang/swift#49438

(0 评论) (0 反应) (0 负责人)Swift (69,989 star) (10,719 fork)batch import

compilergood first issueimprovement

描述


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.

贡献者指南

技术栈: swiftcpp
领域: performance
议题类型: performance
难度: 4
预计时间: 3-5 days
活动状态: stale
清晰度: needs investigation
前置要求: Understanding of LLVM IRFamiliarity with Swift runtime functionsKnowledge of C++
新手友好度: 20
研究方向: 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.