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LibVideo/VP9: Index inter-frame references with named fields or an enum

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Previously, we were using size_t, often coerced from bool or u8, to
index reference pairs. Now, they must either be taken directly from
named fields or indexed using the `ReferenceIndex` enum with options
`primary` and `secondary`. With a more explicit method of indexing
these, the compiler can aid in using reference pairs correctly, and
fuzzers may be able to detect undefined behavior more easily.
This commit is contained in:
Zaggy1024 2022-11-25 03:03:22 -06:00 • committed by Andreas Kling
parent 3af4deba6d
commit f4761dab09
8 changed files with 174 additions and 157 deletions
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39
Userland/Libraries/LibVideo/VP9/Context.h
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@ -19,27 +19,30 @@
namespace Video::VP9 {
template<typename T>
struct Pair {
T a;
T b;
struct ReferencePair {
T primary;
T secondary;
T& operator[](u8 index)
T& operator[](ReferenceIndex index)
{
if (index == 0)
return a;
if (index == 1)
return b;
VERIFY_NOT_REACHED();
switch (index) {
case ReferenceIndex::Primary:
return primary;
case ReferenceIndex::Secondary:
return secondary;
default:
VERIFY_NOT_REACHED();
}
}
T const& operator[](u8 index) const
T const& operator[](ReferenceIndex index) const
{
return const_cast<Pair<T>&>(*this)[index];
return const_cast<ReferencePair<T>&>(*this)[index];
}
};
typedef Pair<ReferenceFrameType> ReferenceFramePair;
typedef Pair<MotionVector> MotionVectorPair;
typedef ReferencePair<ReferenceFrameType> ReferenceFramePair;
typedef ReferencePair<MotionVector> MotionVectorPair;
template<typename T>
class Vector2D;
@ -201,8 +204,8 @@ struct TokensContext {
// Block context that is kept for the lifetime of a frame.
struct FrameBlockContext {
bool is_intra_predicted() const { return ref_frames[0] == ReferenceFrameType::None; }
bool is_single_reference() const { return ref_frames[1] == ReferenceFrameType::None; }
bool is_intra_predicted() const { return ref_frames.primary == ReferenceFrameType::None; }
bool is_single_reference() const { return ref_frames.secondary == ReferenceFrameType::None; }
MotionVectorPair primary_motion_vector_pair() const { return sub_block_motion_vectors[3]; }
bool is_available { false };
@ -410,8 +413,8 @@ struct BlockContext {
TXSize tx_size { TXSize::TX_4x4 };
ReferenceFramePair reference_frame_types;
bool is_inter_predicted() const { return reference_frame_types[0] > ReferenceFrameType::None; }
bool is_compound() const { return reference_frame_types[1] > ReferenceFrameType::None; }
bool is_inter_predicted() const { return reference_frame_types.primary != ReferenceFrameType::None; }
bool is_compound() const { return reference_frame_types.secondary != ReferenceFrameType::None; }
Array<PredictionMode, 4> sub_block_prediction_modes;
PredictionMode y_prediction_mode() const { return sub_block_prediction_modes.last(); }
@ -428,7 +431,7 @@ struct BlockMotionVectorCandidateSet {
MotionVector best_vector;
};
using BlockMotionVectorCandidates = Pair<BlockMotionVectorCandidateSet>;
using BlockMotionVectorCandidates = ReferencePair<BlockMotionVectorCandidateSet>;
struct MotionVectorCandidate {
ReferenceFrameType type;