From 23a4012aeb25b1bf19da9ad393fccf3e1e531b5c Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 21 Jan 2024 15:19:40 +0530
Subject: [PATCH] Add an env var to turn off use of SIMD instructions

---
 docs/glossary.rst   | 5 +++++
 kitty/simd-string.c | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/docs/glossary.rst b/docs/glossary.rst
index 77437b696..21f248166 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -230,3 +230,8 @@ Variables that kitty sets when running child programs
 
    Set to ``1`` when kitty is running a shell because of the ``--hold`` flag. Can
    be used to specialize shell behavior in the shell rc files as desired.
+
+.. envvar:: KITTY_NO_SIMD
+
+   Set it to any value to prevent kitty from using SIMD CPU vector
+   instructions.
diff --git a/kitty/simd-string.c b/kitty/simd-string.c
index 9c5135f45..8fc717099 100644
--- a/kitty/simd-string.c
+++ b/kitty/simd-string.c
@@ -143,6 +143,9 @@ init_simd(void *x) {
     do_check();
 #endif
 #endif
+    if (getenv("KITTY_NO_SIMD")) {
+        has_avx2 = false; has_sse4_2 = false;
+    }
 
 #undef do_check
     if (has_avx2) {