From eb4618b1b5b8079ad71a7acd4d81b2d0a983426d Mon Sep 17 00:00:00 2001
From: Rhys Perry <pendingchaos02@gmail.com>
Date: Tue, 7 Apr 2026 09:46:27 +0100
Subject: [PATCH] util: fix UBSan error with _mesa_bfloat16_bits_to_float

runtime error: left shift of 65535 by 16 places cannot be represented in type 'int'

This fixes nir_opt_algebraic_pattern_test.bf2f.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Fixes: ecd2d2cf46df ("util: Add functions to convert float to/from bfloat16")
Reviewed-by: Georg Lehmann <dadschoorse@gmail.com>
(cherry picked from commit 72f2b8a034235ff0942fcca8646ad2bb66c8b454)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40979>
---
 .pick_status.json | 2 +-
 src/util/bfloat.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index b39cb0a02f7..0a46b318698 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -3324,7 +3324,7 @@
         "description": "util: fix UBSan error with _mesa_bfloat16_bits_to_float",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "ecd2d2cf46dfc3305a6dc1497815b7b54eef513e",
         "notes": null
diff --git a/src/util/bfloat.h b/src/util/bfloat.h
index 886d55fb8ba..013c38e7e24 100644
--- a/src/util/bfloat.h
+++ b/src/util/bfloat.h
@@ -63,7 +63,7 @@ static inline float
 _mesa_bfloat16_bits_to_float(uint16_t bf)
 {
    union fi x;
-   x.ui = bf << 16;
+   x.ui = (uint32_t)bf << 16;
 
    return x.f;
 }