shithub: dav1d

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Make access into noskip_mask safe across sb64 tile threads

--- a/src/cdef_apply.c

+++ b/src/cdef_apply.c

@@ -152,10 +152,10 @@

                 // check if this 8x8 block had any coded coefficients; if not,

                 // go to the next block

-                const unsigned bx_mask = 3U << (bx & 30);

-                const int by_idx = by & 30;

-                if (!((lflvl[sb128x].noskip_mask[by_idx + 0] |

-                       lflvl[sb128x].noskip_mask[by_idx + 1]) & bx_mask))

+                const unsigned bx_mask = 3U << (bx & 14);

+                const int by_idx = by & 30, bx_idx = (bx & 16) >> 4;

+                if (!((lflvl[sb128x].noskip_mask[by_idx + 0][bx_idx] |

+                       lflvl[sb128x].noskip_mask[by_idx + 1][bx_idx]) & bx_mask))

                 {

                     last_skip = 1;

                     goto next_b;

--- a/src/decode.c

+++ b/src/decode.c

@@ -1811,10 +1811,14 @@

     memset(&t->l.skip[by4], b->skip, bh4);

     memset(&t->a->skip[bx4], b->skip, bw4);

     if (!b->skip) {

-        uint32_t *noskip_mask = &t->lf_mask->noskip_mask[by4];

-        const unsigned mask = ((1ULL << bw4) - 1) << bx4;

-        for (int y = 0; y < bh4; y++)

-            *noskip_mask++ |= mask;

+        uint16_t (*noskip_mask)[2] = &t->lf_mask->noskip_mask[by4];

+        const unsigned mask = (~0U >> (32 - bw4)) << (bx4 & 15);

+        const int bx_idx = (bx4 & 16) >> 4;

+        for (int y = 0; y < bh4; y++, noskip_mask++) {

+            (*noskip_mask)[bx_idx] |= mask;

+            if (bw4 == 32) // this should be mask >> 16, but it's 0xffffffff anyway

+                (*noskip_mask)[1] |= mask;

+        }

     }

     return 0;

--- a/src/lf_mask.h

+++ b/src/lf_mask.h

@@ -53,7 +53,7 @@

     uint32_t filter_y[2 /* 0=col, 1=row */][32][3];

     uint32_t filter_uv[2 /* 0=col, 1=row */][32][2];

     int8_t cdef_idx[4]; // -1 means "unset"

-    uint32_t noskip_mask[32];

+    uint16_t noskip_mask[32][2];

     Av1RestorationUnit lr[3][4];

 } Av1Filter;