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regexec: remove alloca usage in build_trtable
It syncs with gnulib version 1731fef3d. On build_trtable prevent inlining, so that it doesn't bloat the caller's stack and use auto variables instead of alloca/malloc. After these changes, build_trtable's total stack allocation is only 20 KiB on a 64-bit machine, and this is less than glibc's 64 KiB cutoff so there's little point to using alloca to shrink it. Checked on x86_64-linux-gnu.
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@ -3247,7 +3247,7 @@ expand_bkref_cache (re_match_context_t *mctx, re_node_set *cur_nodes,
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/* Build transition table for the state.
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Return true if successful. */
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static bool
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static bool __attribute_noinline__
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build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
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{
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reg_errcode_t err;
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@ -3255,36 +3255,20 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
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int ch;
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bool need_word_trtable = false;
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bitset_word_t elem, mask;
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bool dests_node_malloced = false;
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bool dest_states_malloced = false;
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Idx ndests; /* Number of the destination states from 'state'. */
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re_dfastate_t **trtable;
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re_dfastate_t **dest_states = NULL, **dest_states_word, **dest_states_nl;
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re_node_set follows, *dests_node;
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bitset_t *dests_ch;
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re_dfastate_t *dest_states[SBC_MAX];
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re_dfastate_t *dest_states_word[SBC_MAX];
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re_dfastate_t *dest_states_nl[SBC_MAX];
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re_node_set follows;
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bitset_t acceptable;
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struct dests_alloc
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{
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re_node_set dests_node[SBC_MAX];
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bitset_t dests_ch[SBC_MAX];
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} *dests_alloc;
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/* We build DFA states which corresponds to the destination nodes
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from 'state'. 'dests_node[i]' represents the nodes which i-th
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destination state contains, and 'dests_ch[i]' represents the
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characters which i-th destination state accepts. */
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if (__libc_use_alloca (sizeof (struct dests_alloc)))
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dests_alloc = (struct dests_alloc *) alloca (sizeof (struct dests_alloc));
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else
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{
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dests_alloc = re_malloc (struct dests_alloc, 1);
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if (__glibc_unlikely (dests_alloc == NULL))
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return false;
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dests_node_malloced = true;
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}
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dests_node = dests_alloc->dests_node;
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dests_ch = dests_alloc->dests_ch;
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re_node_set dests_node[SBC_MAX];
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bitset_t dests_ch[SBC_MAX];
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/* Initialize transition table. */
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state->word_trtable = state->trtable = NULL;
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@ -3294,8 +3278,6 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
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ndests = group_nodes_into_DFAstates (dfa, state, dests_node, dests_ch);
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if (__glibc_unlikely (ndests <= 0))
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{
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if (dests_node_malloced)
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re_free (dests_alloc);
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/* Return false in case of an error, true otherwise. */
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if (ndests == 0)
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{
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@ -3310,38 +3292,14 @@ build_trtable (const re_dfa_t *dfa, re_dfastate_t *state)
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err = re_node_set_alloc (&follows, ndests + 1);
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if (__glibc_unlikely (err != REG_NOERROR))
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goto out_free;
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/* Avoid arithmetic overflow in size calculation. */
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size_t ndests_max
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= ((SIZE_MAX - (sizeof (re_node_set) + sizeof (bitset_t)) * SBC_MAX)
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/ (3 * sizeof (re_dfastate_t *)));
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if (__glibc_unlikely (ndests_max < ndests))
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goto out_free;
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if (__libc_use_alloca ((sizeof (re_node_set) + sizeof (bitset_t)) * SBC_MAX
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+ ndests * 3 * sizeof (re_dfastate_t *)))
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dest_states = (re_dfastate_t **)
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alloca (ndests * 3 * sizeof (re_dfastate_t *));
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else
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{
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dest_states = re_malloc (re_dfastate_t *, ndests * 3);
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if (__glibc_unlikely (dest_states == NULL))
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{
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out_free:
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if (dest_states_malloced)
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re_free (dest_states);
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re_node_set_free (&follows);
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for (i = 0; i < ndests; ++i)
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re_node_set_free (dests_node + i);
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if (dests_node_malloced)
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re_free (dests_alloc);
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return false;
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}
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dest_states_malloced = true;
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out_free:
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re_node_set_free (&follows);
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for (i = 0; i < ndests; ++i)
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re_node_set_free (dests_node + i);
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return false;
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}
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dest_states_word = dest_states + ndests;
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dest_states_nl = dest_states_word + ndests;
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bitset_empty (acceptable);
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/* Then build the states for all destinations. */
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@ -3466,16 +3424,9 @@ out_free:
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}
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}
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if (dest_states_malloced)
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re_free (dest_states);
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re_node_set_free (&follows);
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for (i = 0; i < ndests; ++i)
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re_node_set_free (dests_node + i);
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if (dests_node_malloced)
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re_free (dests_alloc);
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return true;
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}
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