issue-link js-issue-link" data-error-text="Failed to load title" data-id="2092541973" data-permission-text="Title is private" data-url="https://github.com/JuliaDebug/LoweredCodeUtils.jl/issues/99" data-hovercard-type="pull_request" data-hovercard-url="/JuliaDebug/LoweredCodeUtils.jl/pull/99/hovercard" href="https://github.com/JuliaDebug/LoweredCodeUtils.jl/pull/99">#99. This is built on top of #116. With this PR, the following test cases now pass correctly: ```julia #Final block is not a `return`: Need to use #`config::SelectiveEvalRecurse` explicitly ex = quote x = 1 yy = 7 @Label loop x += 1 x < 5 || return yy @goto loop end frame = Frame(ModSelective, ex) src = frame.framecode.src edges = CodeEdges(ModSelective, src) config = SelectiveEvalRecurse() isrequired = lines_required(GlobalRef(ModSelective, :x), src, edges, config) selective_eval_fromstart!(config, frame, isrequired, true) @test ModSelective.x == 5 @test !isdefined(ModSelective, :yy) ``` The basic approach is overloading `JuliaInterpreter.step_expr!` and `LoweredCodeUtils.next_or_nothing!` for the new `SelectiveEvalController` type, as described below, to perform correct selective execution. When `SelectiveEvalController` is passed as the `recurse` argument of `selective_eval!`, the selective execution is adjusted as follows: - **Implicit return**: In Julia's IR representation (`CodeInfo`), the final block does not necessarily return and may `goto` another block. And if the `return` statement is not included in the slice in such cases, it is necessary to terminate `selective_eval!` when execution reaches such implicit return statements. `controller.implicit_returns` records the PCs of such return statements, and `selective_eval!` will return when reaching those statements. This is the core part of the fix for the test cases in #99. - **CFG short-cut**: When the successors of a conditional branch are inactive, and it is safe to move the program counter from the conditional branch to the nearest common post-dominator of those successors, this short-cut is taken. This short-cut is not merely an optimization but is actually essential for the correctness of the selective execution. This is because, in `CodeInfo`, even if we simply fall-through dead blocks (i.e., increment the program counter without executing the statements of those blocks), it does not necessarily lead to the nearest common post-dominator block. And now [`lines_required`](@ref) or [`lines_required!`](@ref) will update the `SelectiveEvalController` passed as their argument to be appropriate for the program slice generated. One thing to note is that currently, the `controller` is not be recursed. That said, in Revise, which is the main consumer of LCU, there is no need for recursive selective execution, and so `selective_eval!` does not provide a system for inter-procedural selective evaluation. Accordingly `SelectiveEvalController` does not recurse too, but this can be left as a future extension.

proper termination, take 2#117aviatesk wants to merge 1 commit intomasterJuliaDebug/LoweredCodeUtils.jl:masterfrom avi/implicit-returnJuliaDebug/LoweredCodeUtils.jl:avi/implicit-returnCopy head branch name to clipboard

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proper termination, take 2

proper termination, take 2#117
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