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Diffstat (limited to 'src/test/ui/mir-dataflow/README.md')
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diff --git a/src/test/ui/mir-dataflow/README.md b/src/test/ui/mir-dataflow/README.md deleted file mode 100644 index a3ab14b23..000000000 --- a/src/test/ui/mir-dataflow/README.md +++ /dev/null @@ -1,53 +0,0 @@ -This directory contains unit tests for the MIR-based dataflow -analysis. - -These unit tests check the dataflow analysis by embedding calls to a -special `rustc_peek` intrinsic within the code, in tandem with an -attribute `#[rustc_mir(rustc_peek_maybe_init)]` (\*). With that -attribute in place, `rustc_peek` calls are a signal to the compiler to -lookup the computed dataflow state for the Lvalue corresponding to the -argument expression being fed to `rustc_peek`. If the dataflow state -for that Lvalue is a 1-bit at that point in the control flow, then no -error is emitted by the compiler at that point; if it is a 0-bit, then -that invocation of `rustc_peek` will emit an error with the message -"rustc_peek: bit not set". - -(\*): Or `#[rustc_mir(rustc_peek_maybe_uninit)]`, and perhaps other -variants in the future. - -The end effect is that one can write unit tests for MIR dataflow that -perform simple-queries of the computed dataflow state, and the tests -should be able to be robust in the face of changes to how MIR is -represented or constructed. - ----- - -Sometimes understanding the dataflow results is difficult without -looking at the actual MIR control-flow graph being processed with the -corresponding GEN and KILL sets. - -For a graphviz-rendering with dataflow annotations, add the attribute -`#[rustc_mir(borrowck_graphviz_postflow="/path/to/suffix.dot")]` to -the function in question. (You can change the content of -`"suffix.dot"` to control the filenames used for the output). This -will generate a separate file for each dataflow analysis, adding a -prefix (corresponding to the name of the analysis) to the filename in -each generated output path. - - * For example, the above attribute will currently cause two files to - be generated: `/path/to/maybe_init_suffix.dot` and - `/path/to/maybe_uninit_suffix.dot`. - - * The generated `.dot` file shows both the computed dataflow results - on *entry* to each block, as well as the gen- and kill-sets that - were so-called "transfer functions" summarizing the effect of each - basic block. - - * (In addition to the `borrowck_graphviz_postflow` attribute-key - noted above, there is also `borrowck_graphviz_preflow`; it has the - same interface and generates the same set of files, but it renders - the dataflow state after building the gen- and kill-sets but - *before* running the dataflow analysis itself, so each entry-set is - just the initial default state for that dataflow analysis. This is - less useful for understanding the error message output in these - tests.) |