70 lines
2.2 KiB
Markdown
70 lines
2.2 KiB
Markdown
This folder contains tests for MIR optimizations.
|
|
|
|
The `mir-opt` test format emits MIR to extra files that you can automatically update by specifying
|
|
`--bless` on the command line (just like `ui` tests updating `.stderr` files).
|
|
|
|
# `--bless`able test format
|
|
|
|
By default 32 bit and 64 bit targets use the same dump files, which can be problematic in the
|
|
presence of pointers in constants or other bit width dependent things. In that case you can add
|
|
|
|
```
|
|
// EMIT_MIR_FOR_EACH_BIT_WIDTH
|
|
```
|
|
|
|
to your test, causing separate files to be generated for 32bit and 64bit systems.
|
|
|
|
## Unit testing
|
|
|
|
If you are only testing the behavior of a particular mir-opt pass on some specific input (as is
|
|
usually the case), you should add
|
|
|
|
```
|
|
// unit-test: PassName
|
|
```
|
|
|
|
to the top of the file. This makes sure that other passes don't run which means you'll get the input
|
|
you expected and your test won't break when other code changes.
|
|
|
|
## Emit a diff of the mir for a specific optimization
|
|
|
|
This is what you want most often when you want to see how an optimization changes the MIR.
|
|
|
|
```
|
|
// EMIT_MIR $file_name_of_some_mir_dump.diff
|
|
```
|
|
|
|
## Emit mir after a specific optimization
|
|
|
|
Use this if you are just interested in the final state after an optimization.
|
|
|
|
```
|
|
// EMIT_MIR $file_name_of_some_mir_dump.after.mir
|
|
```
|
|
|
|
## Emit mir before a specific optimization
|
|
|
|
This exists mainly for completeness and is rarely useful.
|
|
|
|
```
|
|
// EMIT_MIR $file_name_of_some_mir_dump.before.mir
|
|
```
|
|
|
|
# FileCheck directives
|
|
|
|
The LLVM FileCheck tool is used to verify the contents of output MIR against `CHECK` directives
|
|
present in the test file. This works on the runtime MIR, generated by `--emit=mir`, and not
|
|
on the output of a individual passes.
|
|
|
|
Use `// skip-filecheck` to prevent FileCheck from running.
|
|
|
|
To check MIR for function `foo`, start with a `// CHECK-LABEL fn foo(` directive.
|
|
|
|
`{{regex}}` syntax allows to match `regex`.
|
|
|
|
`[[name:regex]]` syntax allows to bind `name` to a string matching `regex`, and refer to it
|
|
as `[[name]]` in later directives, `regex` should be written not to match a leading space.
|
|
Use `[[my_local:_.*]]` to name a local, and `[[my_bb:bb.*]]` to name a block.
|
|
|
|
Documentation for FileCheck is available here: https://www.llvm.org/docs/CommandGuide/FileCheck.html
|