52 lines
1.4 KiB
Markdown
52 lines
1.4 KiB
Markdown
This folder contains tests for MIR optimizations.
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The `mir-opt` test format emits MIR to extra files that you can automatically update by specifying
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`--bless` on the command line (just like `ui` tests updating `.stderr` files).
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# `--bless`able test format
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By default 32 bit and 64 bit targets use the same dump files, which can be problematic in the
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presence of pointers in constants or other bit width dependent things. In that case you can add
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```
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// EMIT_MIR_FOR_EACH_BIT_WIDTH
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```
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to your test, causing separate files to be generated for 32bit and 64bit systems.
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## Unit testing
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If you are only testing the behavior of a particular mir-opt pass on some specific input (as is
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usually the case), you should add
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```
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// unit-test: PassName
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```
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to the top of the file. This makes sure that other passes don't run which means you'll get the input
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you expected and your test won't break when other code changes.
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## Emit a diff of the mir for a specific optimization
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This is what you want most often when you want to see how an optimization changes the MIR.
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```
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// EMIT_MIR $file_name_of_some_mir_dump.diff
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```
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## Emit mir after a specific optimization
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Use this if you are just interested in the final state after an optimization.
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```
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// EMIT_MIR $file_name_of_some_mir_dump.after.mir
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```
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## Emit mir before a specific optimization
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This exists mainly for completeness and is rarely useful.
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```
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// EMIT_MIR $file_name_of_some_mir_dump.before.mir
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```
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