[FFmpeg-devel] [PATCH] avcodec/x86/hevc: fix luma 12b overflow

* [FFmpeg-devel] [PATCH] avcodec/x86/hevc: fix luma 12b overflow
@ 2024-02-25  8:27 J. Dekker
  2024-02-25 15:56 ` Ronald S. Bultje
  0 siblings, 1 reply; 9+ messages in thread
From: J. Dekker @ 2024-02-25  8:27 UTC (permalink / raw)
  To: ffmpeg-devel

Weak filter can overflow in delta0 calculation before >> 4 in int16.

Signed-off-by: J. Dekker <jdek@itanimul.li>
---

 I do not know x86 simd at all, so this is just an attempt to fix
 the implementation rather than write extremely performant code.

 Suggestions welcome.

 libavcodec/x86/hevc_deblock.asm | 47 +++++++++++++++++++++++++++++++++
 libavcodec/x86/hevcdsp_init.c   |  8 ------
 2 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/libavcodec/x86/hevc_deblock.asm b/libavcodec/x86/hevc_deblock.asm
index 85ee4800bb..ce9221ebc7 100644
--- a/libavcodec/x86/hevc_deblock.asm
+++ b/libavcodec/x86/hevc_deblock.asm
@@ -541,6 +541,7 @@ ALIGN 16
     add             betaq, r13
     shr             betaq, 3; ((beta + (beta >> 1)) >> 3))
 
+%if %1 < 12
     mova            m13, [pw_8]
     psubw           m12, m4, m3 ; q0 - p0
     psllw           m10, m12, 3; 8 * (q0 - p0)
@@ -553,7 +554,49 @@ ALIGN 16
     paddw           m12, m13; + 8
     psraw           m12, 4; >> 4 , delta0
     PABSW           m13, m12; abs(delta0)
+%else
+    psubw           m12, m4, m3 ; q0 - p0
+    pmovsxwd        m13, m12 ; m13 low
+    movhlps         m12, m12
+    pmovsxwd        m12, m12 ; m12 high
+
+    ; m8 low, m10 high
+    pslld            m8, m13, 3; 8 * (q0 - p0)
+    pslld           m10, m12, 3
+
+    paddd            m8, m13 ; 9 * (q0 - p0)
+    paddd           m10, m12
+
+    psubw           m12, m5, m2 ; q1 - p1
+    pmovsxwd        m13, m12 ; m13 low
+    movhlps         m12, m12
+    pmovsxwd        m12, m12 ; m12 high
 
+    psubd            m8, m13 ; 9 * (q0 - p0) - ( q1 - p1 )
+    psubd           m10, m12
+
+    pslld           m13, m13, 1; 2 * ( q1 - p1 )
+    pslld           m12, m12, 1
+
+    psubd            m8, m13; 9 * (q0 - p0) - 3 * ( q1 - p1 )
+    psubd           m10, m12
+
+    mova            m13, [pw_8]
+    pmovsxwd        m13, m13
+
+    paddd            m8, m13 ; + 8
+    paddd           m10, m13
+
+    psrad            m8, 4; >> 4 , delta0
+    psrad           m10, 4
+
+    packssdw        m12, m8
+    packssdw        m10, m10
+
+    psrldq          m12, 8
+    punpcklqdq      m12, m10
+    PABSW           m13, m12; abs(delta0)
+%endif
 
     psllw           m10, m9, 2; 8 * tc
     paddw           m10, m9; 10 * tc
@@ -746,6 +789,7 @@ cglobal hevc_v_loop_filter_luma_10, 4, 14, 16, pix, stride, beta, tc, pix0, src3
 .bypassluma:
     RET
 
+%if cpuflag(avx)
 cglobal hevc_v_loop_filter_luma_12, 4, 14, 16, pix, stride, beta, tc, pix0, src3stride
     sub            pixq, 8
     lea           pix0q, [3 * strideq]
@@ -757,6 +801,7 @@ cglobal hevc_v_loop_filter_luma_12, 4, 14, 16, pix, stride, beta, tc, pix0, src3
     TRANSPOSE8x8W_STORE PASS8ROWS(src3strideq, pixq, r1, pix0q), [pw_pixel_max_12]
 .bypassluma:
     RET
+%endif
 
 ;-----------------------------------------------------------------------------
 ; void ff_hevc_h_loop_filter_luma(uint8_t *_pix, ptrdiff_t _stride, int beta,
@@ -829,6 +874,7 @@ cglobal hevc_h_loop_filter_luma_10, 4, 14, 16, pix, stride, beta, tc, pix0, src3
 .bypassluma:
     RET
 
+%if cpuflag(avx)
 cglobal hevc_h_loop_filter_luma_12, 4, 14, 16, pix, stride, beta, tc, pix0, src3stride
     lea                  src3strideq, [3 * strideq]
     mov                        pix0q, pixq
@@ -859,6 +905,7 @@ cglobal hevc_h_loop_filter_luma_12, 4, 14, 16, pix, stride, beta, tc, pix0, src3
     movdqu     [pixq  + 2 * strideq], m6;  q2
 .bypassluma:
     RET
+%endif
 
 %endmacro
 
diff --git a/libavcodec/x86/hevcdsp_init.c b/libavcodec/x86/hevcdsp_init.c
index f5bc342cd5..e3fcb7b591 100644
--- a/libavcodec/x86/hevcdsp_init.c
+++ b/libavcodec/x86/hevcdsp_init.c
@@ -1205,10 +1205,6 @@ void ff_hevc_dsp_init_x86(HEVCDSPContext *c, const int bit_depth)
         if (EXTERNAL_SSE2(cpu_flags)) {
             c->hevc_v_loop_filter_chroma = ff_hevc_v_loop_filter_chroma_12_sse2;
             c->hevc_h_loop_filter_chroma = ff_hevc_h_loop_filter_chroma_12_sse2;
-            if (ARCH_X86_64) {
-                c->hevc_v_loop_filter_luma = ff_hevc_v_loop_filter_luma_12_sse2;
-                c->hevc_h_loop_filter_luma = ff_hevc_h_loop_filter_luma_12_sse2;
-            }
             SAO_BAND_INIT(12, sse2);
             SAO_EDGE_INIT(12, sse2);
 
@@ -1216,10 +1212,6 @@ void ff_hevc_dsp_init_x86(HEVCDSPContext *c, const int bit_depth)
             c->idct_dc[2] = ff_hevc_idct_16x16_dc_12_sse2;
             c->idct_dc[3] = ff_hevc_idct_32x32_dc_12_sse2;
         }
-        if (EXTERNAL_SSSE3(cpu_flags) && ARCH_X86_64) {
-            c->hevc_v_loop_filter_luma = ff_hevc_v_loop_filter_luma_12_ssse3;
-            c->hevc_h_loop_filter_luma = ff_hevc_h_loop_filter_luma_12_ssse3;
-        }
         if (EXTERNAL_SSE4(cpu_flags) && ARCH_X86_64) {
             EPEL_LINKS(c->put_hevc_epel, 0, 0, pel_pixels, 12, sse4);
             EPEL_LINKS(c->put_hevc_epel, 0, 1, epel_h,     12, sse4);
-- 
2.43.2

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