[FFmpeg-cvslog] configure: Disable inline assembly with nonlocal labels with LTO on Clang on Windows

[Martin Storsjö]

ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Wed Dec 20 14:39:50 2023 +0200| [102045028ee57967973ea90acac41eb747d3c601] | committer: Martin Storsjö

configure: Disable inline assembly with nonlocal labels with LTO on Clang on Windows

The file libavcodec/x86/mlpdsp_init.c uses inline assembly with
nonlocal labels that are referenced outside of the assembly in C.
This fails to link with LTO when built with Clang when targeting
Windows.

The root cause has been reported upstream at
https://github.com/llvm/llvm-project/issues/76046.

Fixes: https://trac.ffmpeg.org/ticket/10548
Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=102045028ee57967973ea90acac41eb747d3c601
---

 configure | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/configure b/configure
index b86c1732c0..590d9c751c 100755
--- a/configure
+++ b/configure
@@ -7399,6 +7399,16 @@ if [ -n "$lto" ]; then
     check_cflags  $lto
     check_ldflags $lto $cpuflags
     disable inline_asm_direct_symbol_refs
+    if test "$cc_type" = "clang"; then
+        # Clang's LTO fails on Windows, when there are references outside
+        # of inline assembly to nonlocal labels defined within inline assembly,
+        # see https://github.com/llvm/llvm-project/issues/76046.
+        case $target_os in
+        mingw32|win32)
+            disable inline_asm_nonlocal_labels
+            ;;
+        esac
+    fi
 fi
 
 enabled ftrapv && check_cflags -ftrapv