[FFmpeg-cvslog] avformat/flvenc: Avoid avio_write(pb, "", 0)

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Tue Mar 19 04:17:18 2024 +0100| [ee736ff80ed967999645147c974cd1941d5e6a21] | committer: Andreas Rheinhardt

avformat/flvenc: Avoid avio_write(pb, "", 0)

When the compiler chooses to inline put_amf_string(pb, ""),
the avio_write(pb, "", 0) can be avoided. Happens with
Clang-17 with -O1 and higher and GCC 13 with -O2 and higher
here.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ee736ff80ed967999645147c974cd1941d5e6a21
---

 libavformat/flvenc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavformat/flvenc.c b/libavformat/flvenc.c
index 7e410e627e..a7d4fa46a2 100644
--- a/libavformat/flvenc.c
+++ b/libavformat/flvenc.c
@@ -231,6 +231,9 @@ static void put_amf_string(AVIOContext *pb, const char *str)
 {
     size_t len = strlen(str);
     avio_wb16(pb, len);
+    // Avoid avio_write() if put_amf_string(pb, "") is inlined.
+    if (av_builtin_constant_p(len == 0) && len == 0)
+        return;
     avio_write(pb, str, len);
 }