In the previous code, the success block of `lhs` would jump directly to the
success block of `rhs`. However, `rhs_success_block` could already contain
statements that are specific to the RHS, and the direct goto causes them to be
executed in the LHS success path as well.
This patch therefore creates a fresh block that the LHS and RHS success blocks
can both jump to.
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).
--blessable 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.
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.
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