[llvm] [docs] Mention ffmpeg and dav1d in llvm-test-suite (PR #120570)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo created https://github.com/llvm/llvm-project/pull/120570

Since https://github.com/llvm/llvm-test-suite/pull/182 and https://github.com/llvm/llvm-test-suite/pull/188, these projects can now be added as external projects within llvm-test-suite.

>From e1500bfda5c189a128db677f756a101aac9cc5c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin at martin.st>
Date: Thu, 19 Dec 2024 14:43:04 +0200
Subject: [PATCH] [docs] Mention ffmpeg and dav1d in llvm-test-suite

Since https://github.com/llvm/llvm-test-suite/pull/182 and
https://github.com/llvm/llvm-test-suite/pull/188, these projects
can now be added as external projects within llvm-test-suite.
---
 llvm/docs/TestSuiteGuide.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/llvm/docs/TestSuiteGuide.md b/llvm/docs/TestSuiteGuide.md
index 35984bd6f7b3b3..2761fb8199e640 100644
--- a/llvm/docs/TestSuiteGuide.md
+++ b/llvm/docs/TestSuiteGuide.md
@@ -367,6 +367,18 @@ For the SPEC benchmarks you can switch between the `test`, `train` and
 `ref` input datasets via the `TEST_SUITE_RUN_TYPE` configuration option.
 The `train` dataset is used by default.
 
+In addition to SPEC, the multimedia frameworks ffmpeg and dav1d can also
+be hooked up as external projects in the same way. Adding them doesn't
+add the respective projects' full testsuites though. But by including
+them in llvm-test-suite, a lot more of potentially vectorizable code
+gets compiled - which also can catch compiler bugs merely by triggering
+code generation asserts. There is a small code correctness test that compares
+the output of the compiler generated functions against handwritten assembly
+versions. (On x86, this requires the nasm tool.) The projects also contain
+microbenchmarks for measuring the performance of some functions. See
+the `README.md` files in the respective `ffmpeg` and `dav1d` directories
+under `llvm-test-suite/External` for further details.
+
 
 Custom Suites
 -------------