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Merge "Add fbounds-safety annotations for histogram." into main

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James Zern
2025-08-19 13:58:27 -07:00
committed by Gerrit Code Review
parent 2be405c472 fde90a49e4
commit f2061209d0
1 changed files with 20 additions and 11 deletions
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31
src/utils/huffman_encode_utils.c
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@@ -34,8 +34,11 @@ static int ValuesShouldBeCollapsedToStrideAverage(int a, int b) {
// Change the population counts in a way that the consequent // Change the population counts in a way that the consequent
// Huffman tree compression, especially its RLE-part, give smaller output. // Huffman tree compression, especially its RLE-part, give smaller output.
static void OptimizeHuffmanForRle(int length, uint8_t* const good_for_rle, static void OptimizeHuffmanForRle(int length,
uint32_t* const counts) { uint8_t* const WEBP_COUNTED_BY(length)
good_for_rle,
uint32_t* const WEBP_COUNTED_BY(length)
counts) {
// 1) Let's make the Huffman code more compatible with rle encoding. // 1) Let's make the Huffman code more compatible with rle encoding.
int i; int i;
for (; length >= 0; --length) { for (; length >= 0; --length) {
@@ -167,12 +170,11 @@ static void SetBitDepths(const HuffmanTree* const tree,
// we are not planning to use this with extremely long blocks. // we are not planning to use this with extremely long blocks.
// //
// See https://en.wikipedia.org/wiki/Huffman_coding // See https://en.wikipedia.org/wiki/Huffman_coding
static void GenerateOptimalTree(const uint32_t* const histogram, static void GenerateOptimalTree(
int histogram_size, const uint32_t* const WEBP_COUNTED_BY(histogram_size) histogram,
HuffmanTree* WEBP_BIDI_INDEXABLE tree, int histogram_size, HuffmanTree* WEBP_BIDI_INDEXABLE tree,
int tree_depth_limit, int tree_depth_limit,
uint8_t* WEBP_COUNTED_BY(histogram_size) uint8_t* WEBP_COUNTED_BY(histogram_size) const bit_depths) {
const bit_depths) {
uint32_t count_min; uint32_t count_min;
HuffmanTree* WEBP_BIDI_INDEXABLE tree_pool; HuffmanTree* WEBP_BIDI_INDEXABLE tree_pool;
int tree_size_orig = 0; int tree_size_orig = 0;
@@ -416,10 +418,17 @@ void VP8LCreateHuffmanTree(uint32_t* const histogram, int tree_depth_limit,
uint8_t* const buf_rle, HuffmanTree* const huff_tree, uint8_t* const buf_rle, HuffmanTree* const huff_tree,
HuffmanTreeCode* const huff_code) { HuffmanTreeCode* const huff_code) {
const int num_symbols = huff_code->num_symbols; const int num_symbols = huff_code->num_symbols;
WEBP_UNSAFE_MEMSET(buf_rle, 0, num_symbols * sizeof(*buf_rle)); uint32_t* const WEBP_BIDI_INDEXABLE bounded_histogram =
OptimizeHuffmanForRle(num_symbols, buf_rle, histogram); WEBP_UNSAFE_FORGE_BIDI_INDEXABLE(
uint32_t*, histogram, (size_t)num_symbols * sizeof(*histogram));
uint8_t* const WEBP_BIDI_INDEXABLE bounded_buf_rle =
WEBP_UNSAFE_FORGE_BIDI_INDEXABLE(uint8_t*, buf_rle,
(size_t)num_symbols * sizeof(*buf_rle));
memset(bounded_buf_rle, 0, num_symbols * sizeof(*buf_rle));
OptimizeHuffmanForRle(num_symbols, bounded_buf_rle, bounded_histogram);
GenerateOptimalTree( GenerateOptimalTree(
histogram, num_symbols, bounded_histogram, num_symbols,
WEBP_UNSAFE_FORGE_BIDI_INDEXABLE(HuffmanTree*, huff_tree, WEBP_UNSAFE_FORGE_BIDI_INDEXABLE(HuffmanTree*, huff_tree,
3 * num_symbols * sizeof(*huff_tree)), 3 * num_symbols * sizeof(*huff_tree)),
tree_depth_limit, huff_code->code_lengths); tree_depth_limit, huff_code->code_lengths);