[FFmpeg-cvslog] avcodec/ppc/hpeldsp_altivec: Fix left-shift of negative number

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Fri Mar 29 01:10:10 2024 +0100| [356610a2ac1db9c1908903ee48721b3ce391ba01] | committer: Andreas Rheinhardt

avcodec/ppc/hpeldsp_altivec: Fix left-shift of negative number

It is UB and affected e.g. the vp5 and vp61 FATE tests:
https://fate.ffmpeg.org/report.cgi?time=20240327083327&slot=ppc-linux-gcc-13.2-ubsan-altivec-qemu

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=356610a2ac1db9c1908903ee48721b3ce391ba01
---

 libavcodec/ppc/hpeldsp_altivec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/ppc/hpeldsp_altivec.c b/libavcodec/ppc/hpeldsp_altivec.c
index a531b6b6ec..4bf6b28ed6 100644
--- a/libavcodec/ppc/hpeldsp_altivec.c
+++ b/libavcodec/ppc/hpeldsp_altivec.c
@@ -41,9 +41,9 @@ void ff_put_pixels16_altivec(uint8_t *block, const uint8_t *pixels, ptrdiff_t li
     register vector unsigned char pixelsv1D;
 
     int i;
-    register ptrdiff_t line_size_2 = line_size << 1;
+    register ptrdiff_t line_size_2 = line_size * (1 << 1);
     register ptrdiff_t line_size_3 = line_size + line_size_2;
-    register ptrdiff_t line_size_4 = line_size << 2;
+    register ptrdiff_t line_size_4 = line_size * (1 << 2);
 
 // hand-unrolling the loop by 4 gains about 15%
 // mininum execution time goes from 74 to 60 cycles