../deps/brotli/c/enc/backward_references

Bug Summary

File:	out/../deps/brotli/c/enc/backward_references_hq.c
Warning:	line 428, column 37 The left operand of '+' is a garbage value
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clang -cc1 -cc1 -triple x86_64-unknown-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name backward_references_hq.c -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/home/maurizio/node-v18.6.0/out -resource-dir /usr/local/lib/clang/16.0.0 -D V8_DEPRECATION_WARNINGS -D V8_IMMINENT_DEPRECATION_WARNINGS -D _GLIBCXX_USE_CXX11_ABI=1 -D NODE_OPENSSL_CONF_NAME=nodejs_conf -D NODE_OPENSSL_HAS_QUIC -D __STDC_FORMAT_MACROS -D OPENSSL_NO_PINSHARED -D OPENSSL_THREADS -D OS_LINUX -I ../deps/brotli/c/include -internal-isystem /usr/local/lib/clang/16.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/8/../../../../x86_64-redhat-linux/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -Wno-unused-parameter -fdebug-compilation-dir=/home/maurizio/node-v18.6.0/out -ferror-limit 19 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-08-22-142216-507842-1 -x c ../deps/brotli/c/enc/backward_references_hq.c
1/* Copyright 2013 Google Inc. All Rights Reserved.

 Distributed under MIT license.
 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5*/

7/* Function to find backward reference copies. */

9#include "./backward_references_hq.h"

11#include <string.h>  /* memcpy, memset */

13#include "../common/constants.h"
14#include "../common/context.h"
15#include "../common/platform.h"
16#include <brotli/types.h>
17#include "./command.h"
18#include "./fast_log.h"
19#include "./find_match_length.h"
20#include "./literal_cost.h"
21#include "./memory.h"
22#include "./params.h"
23#include "./prefix.h"
24#include "./quality.h"

26#if defined(__cplusplus) || defined(c_plusplus)
27extern "C" {
28#endif

30/* BrotliCalculateDistanceCodeLimit(BROTLI_MAX_ALLOWED_DISTANCE, 3, 120). */
31#define BROTLI_MAX_EFFECTIVE_DISTANCE_ALPHABET_SIZE544 544

33static const float kInfinity = 1.7e38f;  /* ~= 2 ^ 127 */

35static const uint32_t kDistanceCacheIndex[] = {
0, 1, 2, 3, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1,
37};
38static const int kDistanceCacheOffset[] = {
0, 0, 0, 0, -1, 1, -2, 2, -3, 3, -1, 1, -2, 2, -3, 3
40};

42void BrotliInitZopfliNodes(ZopfliNode* array, size_t length) {
ZopfliNode stub;
size_t i;
stub.length = 1;
stub.distance = 0;
stub.dcode_insert_length = 0;
stub.u.cost = kInfinity;
for (i = 0; i < length; ++i) array[i] = stub;
50}

52static BROTLI_INLINEinline __attribute__((__always_inline__)) uint32_t ZopfliNodeCopyLength(const ZopfliNode* self) {
return self->length & 0x1FFFFFF;
54}

56static BROTLI_INLINEinline __attribute__((__always_inline__)) uint32_t ZopfliNodeLengthCode(const ZopfliNode* self) {
const uint32_t modifier = self->length >> 25;
return ZopfliNodeCopyLength(self) + 9u - modifier;
59}

61static BROTLI_INLINEinline __attribute__((__always_inline__)) uint32_t ZopfliNodeCopyDistance(const ZopfliNode* self) {
return self->distance;
63}

65static BROTLI_INLINEinline __attribute__((__always_inline__)) uint32_t ZopfliNodeDistanceCode(const ZopfliNode* self) {
const uint32_t short_code = self->dcode_insert_length >> 27;
return short_code == 0 ?
    ZopfliNodeCopyDistance(self) + BROTLI_NUM_DISTANCE_SHORT_CODES16 - 1 :
    short_code - 1;
70}

72static BROTLI_INLINEinline __attribute__((__always_inline__)) uint32_t ZopfliNodeCommandLength(const ZopfliNode* self) {
return ZopfliNodeCopyLength(self) + (self->dcode_insert_length & 0x7FFFFFF);
74}

76/* Histogram based cost model for zopflification. */
77typedef struct ZopfliCostModel {
/* The insert and copy length symbols. */
float cost_cmd_[BROTLI_NUM_COMMAND_SYMBOLS704];
float* cost_dist_;
uint32_t distance_histogram_size;
/* Cumulative costs of literals per position in the stream. */
float* literal_costs_;
float min_cost_cmd_;
size_t num_bytes_;
86} ZopfliCostModel;

88static void InitZopfliCostModel(
  MemoryManager* m, ZopfliCostModel* self, const BrotliDistanceParams* dist,
  size_t num_bytes) {
self->num_bytes_ = num_bytes;
self->literal_costs_ = BROTLI_ALLOC(m, float, num_bytes + 2)((num_bytes + 2) > 0 ? ((float*)BrotliAllocate((m), (num_bytes
 + 2) * sizeof(float))) : ((void*)0));
self->cost_dist_ = BROTLI_ALLOC(m, float, dist->alphabet_size_limit)((dist->alphabet_size_limit) > 0 ? ((float*)BrotliAllocate
((m), (dist->alphabet_size_limit) * sizeof(float))) : ((void
*)0));
self->distance_histogram_size = dist->alphabet_size_limit;
if (BROTLI_IS_OOM(m)(!!0)) return;
96}

98static void CleanupZopfliCostModel(MemoryManager* m, ZopfliCostModel* self) {
BROTLI_FREE(m, self->literal_costs_){ BrotliFree((m), (self->literal_costs_)); self->literal_costs_
 = ((void*)0); };
BROTLI_FREE(m, self->cost_dist_){ BrotliFree((m), (self->cost_dist_)); self->cost_dist_
 = ((void*)0); };
101}

103static void SetCost(const uint32_t* histogram, size_t histogram_size,
                  BROTLI_BOOLint literal_histogram, float* cost) {
size_t sum = 0;
size_t missing_symbol_sum;
float log2sum;
float missing_symbol_cost;
size_t i;
for (i = 0; i < histogram_size; i++) {
  sum += histogram[i];
}
log2sum = (float)FastLog2(sum);
missing_symbol_sum = sum;
if (!literal_histogram) {
  for (i = 0; i < histogram_size; i++) {
    if (histogram[i] == 0) missing_symbol_sum++;
  }
}
missing_symbol_cost = (float)FastLog2(missing_symbol_sum) + 2;
for (i = 0; i < histogram_size; i++) {
  if (histogram[i] == 0) {
    cost[i] = missing_symbol_cost;
    continue;
  }

  /* Shannon bits for this symbol. */
  cost[i] = log2sum - (float)FastLog2(histogram[i]);

  /* Cannot be coded with less than 1 bit */
  if (cost[i] < 1) cost[i] = 1;
}
133}

135static void ZopfliCostModelSetFromCommands(ZopfliCostModel* self,
                                         size_t position,
                                         const uint8_t* ringbuffer,
                                         size_t ringbuffer_mask,
                                         const Command* commands,
                                         size_t num_commands,
                                         size_t last_insert_len) {
uint32_t histogram_literal[BROTLI_NUM_LITERAL_SYMBOLS256];
uint32_t histogram_cmd[BROTLI_NUM_COMMAND_SYMBOLS704];
uint32_t histogram_dist[BROTLI_MAX_EFFECTIVE_DISTANCE_ALPHABET_SIZE544];
float cost_literal[BROTLI_NUM_LITERAL_SYMBOLS256];
size_t pos = position - last_insert_len;
float min_cost_cmd = kInfinity;
size_t i;
float* cost_cmd = self->cost_cmd_;

memset(histogram_literal, 0, sizeof(histogram_literal));
memset(histogram_cmd, 0, sizeof(histogram_cmd));
memset(histogram_dist, 0, sizeof(histogram_dist));

for (i = 0; i < num_commands; i++) {
  size_t inslength = commands[i].insert_len_;
  size_t copylength = CommandCopyLen(&commands[i]);
  size_t distcode = commands[i].dist_prefix_ & 0x3FF;
  size_t cmdcode = commands[i].cmd_prefix_;
  size_t j;

  histogram_cmd[cmdcode]++;
  if (cmdcode >= 128) histogram_dist[distcode]++;

  for (j = 0; j < inslength; j++) {
    histogram_literal[ringbuffer[(pos + j) & ringbuffer_mask]]++;
  }

  pos += inslength + copylength;
}

SetCost(histogram_literal, BROTLI_NUM_LITERAL_SYMBOLS256, BROTLI_TRUE1,
        cost_literal);
SetCost(histogram_cmd, BROTLI_NUM_COMMAND_SYMBOLS704, BROTLI_FALSE0,
        cost_cmd);
SetCost(histogram_dist, self->distance_histogram_size, BROTLI_FALSE0,
        self->cost_dist_);

for (i = 0; i < BROTLI_NUM_COMMAND_SYMBOLS704; ++i) {
  min_cost_cmd = BROTLI_MIN(float, min_cost_cmd, cost_cmd[i])(brotli_min_float((min_cost_cmd), (cost_cmd[i])));
}
self->min_cost_cmd_ = min_cost_cmd;

{
  float* literal_costs = self->literal_costs_;
  float literal_carry = 0.0;
  size_t num_bytes = self->num_bytes_;
  literal_costs[0] = 0.0;
  for (i = 0; i < num_bytes; ++i) {
    literal_carry +=
        cost_literal[ringbuffer[(position + i) & ringbuffer_mask]];
    literal_costs[i + 1] = literal_costs[i] + literal_carry;
    literal_carry -= literal_costs[i + 1] - literal_costs[i];
  }
}
196}

198static void ZopfliCostModelSetFromLiteralCosts(ZopfliCostModel* self,
                                             size_t position,
                                             const uint8_t* ringbuffer,
                                             size_t ringbuffer_mask) {
float* literal_costs = self->literal_costs_;
float literal_carry = 0.0;
float* cost_dist = self->cost_dist_;
float* cost_cmd = self->cost_cmd_;
size_t num_bytes = self->num_bytes_;
size_t i;
BrotliEstimateBitCostsForLiterals(position, num_bytes, ringbuffer_mask,
                                  ringbuffer, &literal_costs[1]);
literal_costs[0] = 0.0;
for (i = 0; i < num_bytes; ++i) {
  literal_carry += literal_costs[i + 1];
  literal_costs[i + 1] = literal_costs[i] + literal_carry;
  literal_carry -= literal_costs[i + 1] - literal_costs[i];
}
for (i = 0; i < BROTLI_NUM_COMMAND_SYMBOLS704; ++i) {
  cost_cmd[i] = (float)FastLog2(11 + (uint32_t)i);
}
for (i = 0; i < self->distance_histogram_size; ++i) {
  cost_dist[i] = (float)FastLog2(20 + (uint32_t)i);
}
self->min_cost_cmd_ = (float)FastLog2(11);
223}

225static BROTLI_INLINEinline __attribute__((__always_inline__)) float ZopfliCostModelGetCommandCost(
  const ZopfliCostModel* self, uint16_t cmdcode) {
return self->cost_cmd_[cmdcode];
228}

230static BROTLI_INLINEinline __attribute__((__always_inline__)) float ZopfliCostModelGetDistanceCost(
  const ZopfliCostModel* self, size_t distcode) {
return self->cost_dist_[distcode];
233}

235static BROTLI_INLINEinline __attribute__((__always_inline__)) float ZopfliCostModelGetLiteralCosts(
  const ZopfliCostModel* self, size_t from, size_t to) {
return self->literal_costs_[to] - self->literal_costs_[from];
238}

240static BROTLI_INLINEinline __attribute__((__always_inline__)) float ZopfliCostModelGetMinCostCmd(
  const ZopfliCostModel* self) {
return self->min_cost_cmd_;
243}

245/* REQUIRES: len >= 2, start_pos <= pos */
246/* REQUIRES: cost < kInfinity, nodes[start_pos].cost < kInfinity */
247/* Maintains the "ZopfliNode array invariant". */
248static BROTLI_INLINEinline __attribute__((__always_inline__)) void UpdateZopfliNode(ZopfliNode* nodes, size_t pos,
  size_t start_pos, size_t len, size_t len_code, size_t dist,
  size_t short_code, float cost) {
ZopfliNode* next = &nodes[pos + len];
next->length = (uint32_t)(len | ((len + 9u - len_code) << 25));
next->distance = (uint32_t)dist;
next->dcode_insert_length = (uint32_t)(
    (short_code << 27) | (pos - start_pos));
next->u.cost = cost;
257}

259typedef struct PosData {
size_t pos;
int distance_cache[4];
float costdiff;
float cost;
264} PosData;

266/* Maintains the smallest 8 cost difference together with their positions */
267typedef struct StartPosQueue {
PosData q_[8];
size_t idx_;
270} StartPosQueue;

272static BROTLI_INLINEinline __attribute__((__always_inline__)) void InitStartPosQueue(StartPosQueue* self) {
self->idx_ = 0;
274}

276static size_t StartPosQueueSize(const StartPosQueue* self) {
return BROTLI_MIN(size_t, self->idx_, 8)(brotli_min_size_t((self->idx_), (8)));
278}

280static void StartPosQueuePush(StartPosQueue* self, const PosData* posdata) {
size_t offset = ~(self->idx_++) & 7;
size_t len = StartPosQueueSize(self);
size_t i;
PosData* q = self->q_;
q[offset] = *posdata;
/* Restore the sorted order. In the list of |len| items at most |len - 1|
   adjacent element comparisons / swaps are required. */
for (i = 1; i < len; ++i) {
  if (q[offset & 7].costdiff > q[(offset + 1) & 7].costdiff) {
    BROTLI_SWAP(PosData, q, offset & 7, (offset + 1) & 7){ PosData __brotli_swap_tmp = (q)[(offset & 7)]; (q)[(offset
 & 7)] = (q)[((offset + 1) & 7)]; (q)[((offset + 1) &
 7)] = __brotli_swap_tmp; };
  }
  ++offset;
}
294}

296static const PosData* StartPosQueueAt(const StartPosQueue* self, size_t k) {
return &self->q_[(k - self->idx_) & 7];
298}

300/* Returns the minimum possible copy length that can improve the cost of any */
301/* future position. */
302static size_t ComputeMinimumCopyLength(const float start_cost,
                                     const ZopfliNode* nodes,
                                     const size_t num_bytes,
                                     const size_t pos) {
/* Compute the minimum possible cost of reaching any future position. */
float min_cost = start_cost;
size_t len = 2;
size_t next_len_bucket = 4;
size_t next_len_offset = 10;
while (pos + len <= num_bytes && nodes[pos + len].u.cost <= min_cost) {
  /* We already reached (pos + len) with no more cost than the minimum
     possible cost of reaching anything from this pos, so there is no point in
     looking for lengths <= len. */
  ++len;
  if (len == next_len_offset) {
    /* We reached the next copy length code bucket, so we add one more
       extra bit to the minimum cost. */
    min_cost += 1.0f;
    next_len_offset += next_len_bucket;
    next_len_bucket *= 2;
  }
}
return len;
325}

327/* REQUIRES: nodes[pos].cost < kInfinity
 REQUIRES: nodes[0..pos] satisfies that "ZopfliNode array invariant". */
329static uint32_t ComputeDistanceShortcut(const size_t block_start,
                                      const size_t pos,
                                      const size_t max_backward_limit,
                                      const size_t gap,
                                      const ZopfliNode* nodes) {
const size_t clen = ZopfliNodeCopyLength(&nodes[pos]);
const size_t ilen = nodes[pos].dcode_insert_length & 0x7FFFFFF;
const size_t dist = ZopfliNodeCopyDistance(&nodes[pos]);
/* Since |block_start + pos| is the end position of the command, the copy part
   starts from |block_start + pos - clen|. Distances that are greater than
   this or greater than |max_backward_limit| + |gap| are static dictionary
   references, and do not update the last distances.
   Also distance code 0 (last distance) does not update the last distances. */
if (pos == 0) {
  return 0;
} else if (dist + clen <= block_start + pos + gap &&
           dist <= max_backward_limit + gap &&
           ZopfliNodeDistanceCode(&nodes[pos]) > 0) {
  return (uint32_t)pos;
} else {
  return nodes[pos - clen - ilen].u.shortcut;
}
351}

353/* Fills in dist_cache[0..3] with the last four distances (as defined by
 Section 4. of the Spec) that would be used at (block_start + pos) if we
 used the shortest path of commands from block_start, computed from
 nodes[0..pos]. The last four distances at block_start are in
 starting_dist_cache[0..3].
 REQUIRES: nodes[pos].cost < kInfinity
 REQUIRES: nodes[0..pos] satisfies that "ZopfliNode array invariant". */
360static void ComputeDistanceCache(const size_t pos,
                               const int* starting_dist_cache,
                               const ZopfliNode* nodes,
                               int* dist_cache) {
int idx = 0;
size_t p = nodes[pos].u.shortcut;
while (idx < 4 && p > 0) {
  const size_t ilen = nodes[p].dcode_insert_length & 0x7FFFFFF;
  const size_t clen = ZopfliNodeCopyLength(&nodes[p]);
  const size_t dist = ZopfliNodeCopyDistance(&nodes[p]);
  dist_cache[idx++] = (int)dist;
  /* Because of prerequisite, p >= clen + ilen >= 2. */
  p = nodes[p - clen - ilen].u.shortcut;
}
for (; idx < 4; ++idx) {
  dist_cache[idx] = *starting_dist_cache++;
}
377}

379/* Maintains "ZopfliNode array invariant" and pushes node to the queue, if it
 is eligible. */
381static void EvaluateNode(
  const size_t block_start, const size_t pos, const size_t max_backward_limit,
  const size_t gap, const int* starting_dist_cache,
  const ZopfliCostModel* model, StartPosQueue* queue, ZopfliNode* nodes) {
/* Save cost, because ComputeDistanceCache invalidates it. */
float node_cost = nodes[pos].u.cost;
nodes[pos].u.shortcut = ComputeDistanceShortcut(
    block_start, pos, max_backward_limit, gap, nodes);
if (node_cost <= ZopfliCostModelGetLiteralCosts(model, 0, pos)) {
15
←
Assuming the condition is false→
16
←
Taking false branch→
  PosData posdata;
  posdata.pos = pos;
  posdata.cost = node_cost;
  posdata.costdiff = node_cost -
      ZopfliCostModelGetLiteralCosts(model, 0, pos);
  ComputeDistanceCache(
      pos, starting_dist_cache, nodes, posdata.distance_cache);
  StartPosQueuePush(queue, &posdata);
}
399}

401/* Returns longest copy length. */
402static size_t UpdateNodes(
  const size_t num_bytes, const size_t block_start, const size_t pos,
  const uint8_t* ringbuffer, const size_t ringbuffer_mask,
  const BrotliEncoderParams* params, const size_t max_backward_limit,
  const int* starting_dist_cache, const size_t num_matches,
  const BackwardMatch* matches, const ZopfliCostModel* model,
  StartPosQueue* queue, ZopfliNode* nodes) {
const size_t stream_offset = params->stream_offset;
const size_t cur_ix = block_start + pos;
const size_t cur_ix_masked = cur_ix & ringbuffer_mask;
const size_t max_distance = BROTLI_MIN(size_t, cur_ix, max_backward_limit)(brotli_min_size_t((cur_ix), (max_backward_limit)));
const size_t dictionary_start = BROTLI_MIN(size_t,(brotli_min_size_t((cur_ix + stream_offset), (max_backward_limit
)))
    cur_ix + stream_offset, max_backward_limit)(brotli_min_size_t((cur_ix + stream_offset), (max_backward_limit
)));
const size_t max_len = num_bytes - pos;
const size_t max_zopfli_len = MaxZopfliLen(params);
const size_t max_iters = MaxZopfliCandidates(params);
size_t min_len;
size_t result = 0;
size_t k;
size_t gap = 0;

EvaluateNode(block_start + stream_offset, pos, max_backward_limit, gap,
14
←
Calling 'EvaluateNode'→
17
←
Returning from 'EvaluateNode'→
    starting_dist_cache, model, queue, nodes);

{
  const PosData* posdata = StartPosQueueAt(queue, 0);
  float min_cost = (posdata->cost + ZopfliCostModelGetMinCostCmd(model) +
18
←
The left operand of '+' is a garbage value
      ZopfliCostModelGetLiteralCosts(model, posdata->pos, pos));
  min_len = ComputeMinimumCopyLength(min_cost, nodes, num_bytes, pos);
}

/* Go over the command starting positions in order of increasing cost
   difference. */
for (k = 0; k < max_iters && k < StartPosQueueSize(queue); ++k) {
  const PosData* posdata = StartPosQueueAt(queue, k);
  const size_t start = posdata->pos;
  const uint16_t inscode = GetInsertLengthCode(pos - start);
  const float start_costdiff = posdata->costdiff;
  const float base_cost = start_costdiff + (float)GetInsertExtra(inscode) +
      ZopfliCostModelGetLiteralCosts(model, 0, pos);

  /* Look for last distance matches using the distance cache from this
     starting position. */
  size_t best_len = min_len - 1;
  size_t j = 0;
  for (; j < BROTLI_NUM_DISTANCE_SHORT_CODES16 && best_len < max_len; ++j) {
    const size_t idx = kDistanceCacheIndex[j];
    const size_t backward =
        (size_t)(posdata->distance_cache[idx] + kDistanceCacheOffset[j]);
    size_t prev_ix = cur_ix - backward;
    size_t len = 0;
    uint8_t continuation = ringbuffer[cur_ix_masked + best_len];
    if (cur_ix_masked + best_len > ringbuffer_mask) {
      break;
    }
    if (BROTLI_PREDICT_FALSE(backward > dictionary_start + gap)(__builtin_expect(backward > dictionary_start + gap, 0))) {
      /* Word dictionary -> ignore. */
      continue;
    }
    if (backward <= max_distance) {
      /* Regular backward reference. */
      if (prev_ix >= cur_ix) {
        continue;
      }

      prev_ix &= ringbuffer_mask;
      if (prev_ix + best_len > ringbuffer_mask ||
          continuation != ringbuffer[prev_ix + best_len]) {
        continue;
      }
      len = FindMatchLengthWithLimit(&ringbuffer[prev_ix],
                                     &ringbuffer[cur_ix_masked],
                                     max_len);
    } else {
      /* "Gray" area. It is addressable by decoder, but this encoder
         instance does not have that data -> should not touch it. */
      continue;
    }
    {
      const float dist_cost = base_cost +
          ZopfliCostModelGetDistanceCost(model, j);
      size_t l;
      for (l = best_len + 1; l <= len; ++l) {
        const uint16_t copycode = GetCopyLengthCode(l);
        const uint16_t cmdcode =
            CombineLengthCodes(inscode, copycode, j == 0);
        const float cost = (cmdcode < 128 ? base_cost : dist_cost) +
            (float)GetCopyExtra(copycode) +
            ZopfliCostModelGetCommandCost(model, cmdcode);
        if (cost < nodes[pos + l].u.cost) {
          UpdateZopfliNode(nodes, pos, start, l, l, backward, j + 1, cost);
          result = BROTLI_MAX(size_t, result, l)(brotli_max_size_t((result), (l)));
        }
        best_len = l;
      }
    }
  }

  /* At higher iterations look only for new last distance matches, since
     looking only for new command start positions with the same distances
     does not help much. */
  if (k >= 2) continue;

  {
    /* Loop through all possible copy lengths at this position. */
    size_t len = min_len;
    for (j = 0; j < num_matches; ++j) {
      BackwardMatch match = matches[j];
      size_t dist = match.distance;
      BROTLI_BOOLint is_dictionary_match =
          TO_BROTLI_BOOL(dist > dictionary_start + gap)(!!(dist > dictionary_start + gap) ? 1 : 0);
      /* We already tried all possible last distance matches, so we can use
         normal distance code here. */
      size_t dist_code = dist + BROTLI_NUM_DISTANCE_SHORT_CODES16 - 1;
      uint16_t dist_symbol;
      uint32_t distextra;
      uint32_t distnumextra;
      float dist_cost;
      size_t max_match_len;
      PrefixEncodeCopyDistance(
          dist_code, params->dist.num_direct_distance_codes,
          params->dist.distance_postfix_bits, &dist_symbol, &distextra);
      distnumextra = dist_symbol >> 10;
      dist_cost = base_cost + (float)distnumextra +
          ZopfliCostModelGetDistanceCost(model, dist_symbol & 0x3FF);

      /* Try all copy lengths up until the maximum copy length corresponding
         to this distance. If the distance refers to the static dictionary, or
         the maximum length is long enough, try only one maximum length. */
      max_match_len = BackwardMatchLength(&match);
      if (len < max_match_len &&
          (is_dictionary_match || max_match_len > max_zopfli_len)) {
        len = max_match_len;
      }
      for (; len <= max_match_len; ++len) {
        const size_t len_code =
            is_dictionary_match ? BackwardMatchLengthCode(&match) : len;
        const uint16_t copycode = GetCopyLengthCode(len_code);
        const uint16_t cmdcode = CombineLengthCodes(inscode, copycode, 0);
        const float cost = dist_cost + (float)GetCopyExtra(copycode) +
            ZopfliCostModelGetCommandCost(model, cmdcode);
        if (cost < nodes[pos + len].u.cost) {
          UpdateZopfliNode(nodes, pos, start, len, len_code, dist, 0, cost);
          result = BROTLI_MAX(size_t, result, len)(brotli_max_size_t((result), (len)));
        }
      }
    }
  }
}
return result;
552}

554static size_t ComputeShortestPathFromNodes(size_t num_bytes,
  ZopfliNode* nodes) {
size_t index = num_bytes;
size_t num_commands = 0;
while ((nodes[index].dcode_insert_length & 0x7FFFFFF) == 0 &&
    nodes[index].length == 1) --index;
nodes[index].u.next = BROTLI_UINT32_MAX(~((uint32_t)0));
while (index != 0) {
  size_t len = ZopfliNodeCommandLength(&nodes[index]);
  index -= len;
  nodes[index].u.next = (uint32_t)len;
  num_commands++;
}
return num_commands;
568}

570/* REQUIRES: nodes != NULL and len(nodes) >= num_bytes + 1 */
571void BrotliZopfliCreateCommands(const size_t num_bytes,
  const size_t block_start, const ZopfliNode* nodes, int* dist_cache,
  size_t* last_insert_len, const BrotliEncoderParams* params,
  Command* commands, size_t* num_literals) {
const size_t stream_offset = params->stream_offset;
const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin)(((size_t)1 << (params->lgwin)) - 16);
size_t pos = 0;
uint32_t offset = nodes[0].u.next;
size_t i;
size_t gap = 0;
for (i = 0; offset != BROTLI_UINT32_MAX(~((uint32_t)0)); i++) {
  const ZopfliNode* next = &nodes[pos + offset];
  size_t copy_length = ZopfliNodeCopyLength(next);
  size_t insert_length = next->dcode_insert_length & 0x7FFFFFF;
  pos += insert_length;
  offset = next->u.next;
  if (i == 0) {
    insert_length += *last_insert_len;
    *last_insert_len = 0;
  }
  {
    size_t distance = ZopfliNodeCopyDistance(next);
    size_t len_code = ZopfliNodeLengthCode(next);
    size_t dictionary_start = BROTLI_MIN(size_t,(brotli_min_size_t((block_start + pos + stream_offset), (max_backward_limit
)))
        block_start + pos + stream_offset, max_backward_limit)(brotli_min_size_t((block_start + pos + stream_offset), (max_backward_limit
)));
    BROTLI_BOOLint is_dictionary =
        TO_BROTLI_BOOL(distance > dictionary_start + gap)(!!(distance > dictionary_start + gap) ? 1 : 0);
    size_t dist_code = ZopfliNodeDistanceCode(next);
    InitCommand(&commands[i], &params->dist, insert_length,
        copy_length, (int)len_code - (int)copy_length, dist_code);

    if (!is_dictionary && dist_code > 0) {
      dist_cache[3] = dist_cache[2];
      dist_cache[2] = dist_cache[1];
      dist_cache[1] = dist_cache[0];
      dist_cache[0] = (int)distance;
    }
  }

  *num_literals += insert_length;
  pos += copy_length;
}
*last_insert_len += num_bytes - pos;
614}

616static size_t ZopfliIterate(size_t num_bytes, size_t position,
  const uint8_t* ringbuffer, size_t ringbuffer_mask,
  const BrotliEncoderParams* params, const size_t gap, const int* dist_cache,
  const ZopfliCostModel* model, const uint32_t* num_matches,
  const BackwardMatch* matches, ZopfliNode* nodes) {
const size_t stream_offset = params->stream_offset;
const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin)(((size_t)1 << (params->lgwin)) - 16);
const size_t max_zopfli_len = MaxZopfliLen(params);
StartPosQueue queue;
size_t cur_match_pos = 0;
size_t i;
nodes[0].length = 0;
nodes[0].u.cost = 0;
InitStartPosQueue(&queue);
for (i = 0; i + 3 < num_bytes; i++) {
  size_t skip = UpdateNodes(num_bytes, position, i, ringbuffer,
      ringbuffer_mask, params, max_backward_limit, dist_cache,
      num_matches[i], &matches[cur_match_pos], model, &queue, nodes);
  if (skip < BROTLI_LONG_COPY_QUICK_STEP16384) skip = 0;
  cur_match_pos += num_matches[i];
  if (num_matches[i] == 1 &&
      BackwardMatchLength(&matches[cur_match_pos - 1]) > max_zopfli_len) {
    skip = BROTLI_MAX(size_t,(brotli_max_size_t((BackwardMatchLength(&matches[cur_match_pos
 - 1])), (skip)))
        BackwardMatchLength(&matches[cur_match_pos - 1]), skip)(brotli_max_size_t((BackwardMatchLength(&matches[cur_match_pos
 - 1])), (skip)));
  }
  if (skip > 1) {
    skip--;
    while (skip) {
      i++;
      if (i + 3 >= num_bytes) break;
      EvaluateNode(position + stream_offset, i, max_backward_limit, gap,
          dist_cache, model, &queue, nodes);
      cur_match_pos += num_matches[i];
      skip--;
    }
  }
}
return ComputeShortestPathFromNodes(num_bytes, nodes);
654}

656/* REQUIRES: nodes != NULL and len(nodes) >= num_bytes + 1 */
657size_t BrotliZopfliComputeShortestPath(MemoryManager* m, size_t num_bytes,
  size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
  ContextLut literal_context_lut, const BrotliEncoderParams* params,
  const int* dist_cache, Hasher* hasher, ZopfliNode* nodes) {
const size_t stream_offset = params->stream_offset;
const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin)(((size_t)1 << (params->lgwin)) - 16);
const size_t max_zopfli_len = MaxZopfliLen(params);
ZopfliCostModel model;
StartPosQueue queue;
BackwardMatch matches[2 * (MAX_NUM_MATCHES_H10128 + 64)];
const size_t store_end = num_bytes >= StoreLookaheadH10() ?
5
←
Assuming the condition is false→
6
←
'?' condition is false→
    position + num_bytes - StoreLookaheadH10() + 1 : position;
size_t i;
size_t gap = 0;
size_t lz_matches_offset = 0;
BROTLI_UNUSED(literal_context_lut)(void)(literal_context_lut);
nodes[0].length = 0;
nodes[0].u.cost = 0;
InitZopfliCostModel(m, &model, &params->dist, num_bytes);
if (BROTLI_IS_OOM(m)(!!0)) return 0;
7
←
Taking false branch→
ZopfliCostModelSetFromLiteralCosts(
    &model, position, ringbuffer, ringbuffer_mask);
InitStartPosQueue(&queue);
8
←
Calling 'InitStartPosQueue'→
9
←
Returning from 'InitStartPosQueue'→
for (i = 0; i + HashTypeLengthH10() - 1 < num_bytes; i++) {
10
←
Assuming the condition is true→
11
←
Loop condition is true.  Entering loop body→
  const size_t pos = position + i;
  const size_t max_distance = BROTLI_MIN(size_t, pos, max_backward_limit)(brotli_min_size_t((pos), (max_backward_limit)));
  const size_t dictionary_start = BROTLI_MIN(size_t,(brotli_min_size_t((pos + stream_offset), (max_backward_limit
)))
      pos + stream_offset, max_backward_limit)(brotli_min_size_t((pos + stream_offset), (max_backward_limit
)));
  size_t skip;
  size_t num_matches;
  num_matches = FindAllMatchesH10(&hasher->privat._H10,
      &params->dictionary,
      ringbuffer, ringbuffer_mask, pos, num_bytes - i, max_distance,
      dictionary_start + gap, params, &matches[lz_matches_offset]);
  if (num_matches > 0 &&
12
←
Assuming 'num_matches' is <= 0→
      BackwardMatchLength(&matches[num_matches - 1]) > max_zopfli_len) {
    matches[0] = matches[num_matches - 1];
    num_matches = 1;
  }
  skip = UpdateNodes(num_bytes, position, i, ringbuffer, ringbuffer_mask,
13
←
Calling 'UpdateNodes'→
      params, max_backward_limit, dist_cache, num_matches, matches, &model,
      &queue, nodes);
  if (skip < BROTLI_LONG_COPY_QUICK_STEP16384) skip = 0;
  if (num_matches == 1 && BackwardMatchLength(&matches[0]) > max_zopfli_len) {
    skip = BROTLI_MAX(size_t, BackwardMatchLength(&matches[0]), skip)(brotli_max_size_t((BackwardMatchLength(&matches[0])), (skip
)));
  }
  if (skip > 1) {
    /* Add the tail of the copy to the hasher. */
    StoreRangeH10(&hasher->privat._H10,
        ringbuffer, ringbuffer_mask, pos + 1, BROTLI_MIN((brotli_min_size_t((pos + skip), (store_end)))
        size_t, pos + skip, store_end)(brotli_min_size_t((pos + skip), (store_end))));
    skip--;
    while (skip) {
      i++;
      if (i + HashTypeLengthH10() - 1 >= num_bytes) break;
      EvaluateNode(position + stream_offset, i, max_backward_limit, gap,
          dist_cache, &model, &queue, nodes);
      skip--;
    }
  }
}
CleanupZopfliCostModel(m, &model);
return ComputeShortestPathFromNodes(num_bytes, nodes);
720}

722void BrotliCreateZopfliBackwardReferences(MemoryManager* m, size_t num_bytes,
  size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
  ContextLut literal_context_lut, const BrotliEncoderParams* params,
  Hasher* hasher, int* dist_cache, size_t* last_insert_len,
  Command* commands, size_t* num_commands, size_t* num_literals) {
ZopfliNode* nodes = BROTLI_ALLOC(m, ZopfliNode, num_bytes + 1)((num_bytes + 1) > 0 ? ((ZopfliNode*)BrotliAllocate((m), (
num_bytes + 1) * sizeof(ZopfliNode))) : ((void*)0));
1
Assuming the condition is true→
2
←
'?' condition is true→
if (BROTLI_IS_OOM(m)(!!0) || BROTLI_IS_NULL(nodes)(!!0)) return;
3
←
Taking false branch→
BrotliInitZopfliNodes(nodes, num_bytes + 1);
*num_commands += BrotliZopfliComputeShortestPath(m, num_bytes,
4
←
Calling 'BrotliZopfliComputeShortestPath'→
    position, ringbuffer, ringbuffer_mask, literal_context_lut, params,
    dist_cache, hasher, nodes);
if (BROTLI_IS_OOM(m)(!!0)) return;
BrotliZopfliCreateCommands(num_bytes, position, nodes, dist_cache,
    last_insert_len, params, commands, num_literals);
BROTLI_FREE(m, nodes){ BrotliFree((m), (nodes)); nodes = ((void*)0); };
737}

739void BrotliCreateHqZopfliBackwardReferences(MemoryManager* m, size_t num_bytes,
  size_t position, const uint8_t* ringbuffer, size_t ringbuffer_mask,
  ContextLut literal_context_lut, const BrotliEncoderParams* params,
  Hasher* hasher, int* dist_cache, size_t* last_insert_len,
  Command* commands, size_t* num_commands, size_t* num_literals) {
const size_t stream_offset = params->stream_offset;
const size_t max_backward_limit = BROTLI_MAX_BACKWARD_LIMIT(params->lgwin)(((size_t)1 << (params->lgwin)) - 16);
uint32_t* num_matches = BROTLI_ALLOC(m, uint32_t, num_bytes)((num_bytes) > 0 ? ((uint32_t*)BrotliAllocate((m), (num_bytes
) * sizeof(uint32_t))) : ((void*)0));
size_t matches_size = 4 * num_bytes;
const size_t store_end = num_bytes >= StoreLookaheadH10() ?
    position + num_bytes - StoreLookaheadH10() + 1 : position;
size_t cur_match_pos = 0;
size_t i;
size_t orig_num_literals;
size_t orig_last_insert_len;
int orig_dist_cache[4];
size_t orig_num_commands;
ZopfliCostModel model;
ZopfliNode* nodes;
BackwardMatch* matches = BROTLI_ALLOC(m, BackwardMatch, matches_size)((matches_size) > 0 ? ((BackwardMatch*)BrotliAllocate((m),
 (matches_size) * sizeof(BackwardMatch))) : ((void*)0));
size_t gap = 0;
size_t shadow_matches = 0;
BROTLI_UNUSED(literal_context_lut)(void)(literal_context_lut);
if (BROTLI_IS_OOM(m)(!!0) || BROTLI_IS_NULL(num_matches)(!!0) ||
    BROTLI_IS_NULL(matches)(!!0)) {
  return;
}
for (i = 0; i + HashTypeLengthH10() - 1 < num_bytes; ++i) {
  const size_t pos = position + i;
  size_t max_distance = BROTLI_MIN(size_t, pos, max_backward_limit)(brotli_min_size_t((pos), (max_backward_limit)));
  size_t dictionary_start = BROTLI_MIN(size_t,(brotli_min_size_t((pos + stream_offset), (max_backward_limit
)))
      pos + stream_offset, max_backward_limit)(brotli_min_size_t((pos + stream_offset), (max_backward_limit
)));
  size_t max_length = num_bytes - i;
  size_t num_found_matches;
  size_t cur_match_end;
  size_t j;
  /* Ensure that we have enough free slots. */
  BROTLI_ENSURE_CAPACITY(m, BackwardMatch, matches, matches_size,{ if (matches_size < (cur_match_pos + 128 + shadow_matches
)) { size_t _new_size = (matches_size == 0) ? (cur_match_pos +
+ shadow_matches) : matches_size; BackwardMatch* new_array
; while (_new_size < (cur_match_pos + 128 + shadow_matches
)) _new_size *= 2; new_array = ((_new_size) > 0 ? ((BackwardMatch
*)BrotliAllocate(((m)), (_new_size) * sizeof(BackwardMatch)))
 : ((void*)0)); if (!(!!0) && !(!!0) && matches_size
 != 0) memcpy(new_array, matches, matches_size * sizeof(BackwardMatch
)); { BrotliFree(((m)), (matches)); matches = ((void*)0); }; matches
 = new_array; matches_size = _new_size; } }
      cur_match_pos + MAX_NUM_MATCHES_H10 + shadow_matches){ if (matches_size < (cur_match_pos + 128 + shadow_matches
)) { size_t _new_size = (matches_size == 0) ? (cur_match_pos +
+ shadow_matches) : matches_size; BackwardMatch* new_array
; while (_new_size < (cur_match_pos + 128 + shadow_matches
)) _new_size *= 2; new_array = ((_new_size) > 0 ? ((BackwardMatch
*)BrotliAllocate(((m)), (_new_size) * sizeof(BackwardMatch)))
 : ((void*)0)); if (!(!!0) && !(!!0) && matches_size
 != 0) memcpy(new_array, matches, matches_size * sizeof(BackwardMatch
)); { BrotliFree(((m)), (matches)); matches = ((void*)0); }; matches
 = new_array; matches_size = _new_size; } };
  if (BROTLI_IS_OOM(m)(!!0)) return;
  num_found_matches = FindAllMatchesH10(&hasher->privat._H10,
      &params->dictionary,
      ringbuffer, ringbuffer_mask, pos, max_length,
      max_distance, dictionary_start + gap, params,
      &matches[cur_match_pos + shadow_matches]);
  cur_match_end = cur_match_pos + num_found_matches;
  for (j = cur_match_pos; j + 1 < cur_match_end; ++j) {
    BROTLI_DCHECK(BackwardMatchLength(&matches[j]) <=
        BackwardMatchLength(&matches[j + 1]));
  }
  num_matches[i] = (uint32_t)num_found_matches;
  if (num_found_matches > 0) {
    const size_t match_len = BackwardMatchLength(&matches[cur_match_end - 1]);
    if (match_len > MAX_ZOPFLI_LEN_QUALITY_11325) {
      const size_t skip = match_len - 1;
      matches[cur_match_pos++] = matches[cur_match_end - 1];
      num_matches[i] = 1;
      /* Add the tail of the copy to the hasher. */
      StoreRangeH10(&hasher->privat._H10,
                    ringbuffer, ringbuffer_mask, pos + 1,
                    BROTLI_MIN(size_t, pos + match_len, store_end)(brotli_min_size_t((pos + match_len), (store_end))));
      memset(&num_matches[i + 1], 0, skip * sizeof(num_matches[0]));
      i += skip;
    } else {
      cur_match_pos = cur_match_end;
    }
  }
}
orig_num_literals = *num_literals;
orig_last_insert_len = *last_insert_len;
memcpy(orig_dist_cache, dist_cache, 4 * sizeof(dist_cache[0]));
orig_num_commands = *num_commands;
nodes = BROTLI_ALLOC(m, ZopfliNode, num_bytes + 1)((num_bytes + 1) > 0 ? ((ZopfliNode*)BrotliAllocate((m), (
num_bytes + 1) * sizeof(ZopfliNode))) : ((void*)0));
if (BROTLI_IS_OOM(m)(!!0) || BROTLI_IS_NULL(nodes)(!!0)) return;
InitZopfliCostModel(m, &model, &params->dist, num_bytes);
if (BROTLI_IS_OOM(m)(!!0)) return;
for (i = 0; i < 2; i++) {
  BrotliInitZopfliNodes(nodes, num_bytes + 1);
  if (i == 0) {
    ZopfliCostModelSetFromLiteralCosts(
        &model, position, ringbuffer, ringbuffer_mask);
  } else {
    ZopfliCostModelSetFromCommands(&model, position, ringbuffer,
        ringbuffer_mask, commands, *num_commands - orig_num_commands,
        orig_last_insert_len);
  }
  *num_commands = orig_num_commands;
  *num_literals = orig_num_literals;
  *last_insert_len = orig_last_insert_len;
  memcpy(dist_cache, orig_dist_cache, 4 * sizeof(dist_cache[0]));
  *num_commands += ZopfliIterate(num_bytes, position, ringbuffer,
      ringbuffer_mask, params, gap, dist_cache, &model, num_matches, matches,
      nodes);
  BrotliZopfliCreateCommands(num_bytes, position, nodes, dist_cache,
      last_insert_len, params, commands, num_literals);
}
CleanupZopfliCostModel(m, &model);
BROTLI_FREE(m, nodes){ BrotliFree((m), (nodes)); nodes = ((void*)0); };
BROTLI_FREE(m, matches){ BrotliFree((m), (matches)); matches = ((void*)0); };
BROTLI_FREE(m, num_matches){ BrotliFree((m), (num_matches)); num_matches = ((void*)0); };
839}

841#if defined(__cplusplus) || defined(c_plusplus)
842}  /* extern "C" */
843#endif