Merging upstream version 1.75.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/mir-opt/README.md b/tests/mir-opt/README.md
index 0721d9f70..39a7b5aea 100644
--- a/tests/mir-opt/README.md
+++ b/tests/mir-opt/README.md
@@ -49,3 +49,21 @@ 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