diff --git a/gcc/sched-deps.cc b/gcc/sched-deps.cc index 010eefe3e20390a5289162cf0454702219be570a..0615007c560a27f3ee4f454c4f457e84541b860a 100644 --- a/gcc/sched-deps.cc +++ b/gcc/sched-deps.cc @@ -4779,24 +4779,59 @@ parse_add_or_inc (struct mem_inc_info *mii, rtx_insn *insn, bool before_mem) /* Once a suitable mem reference has been found and the corresponding data in MII has been filled in, this function is called to find a suitable add or inc insn involving the register we found in the memory - reference. */ + reference. + If successful, this function will create additional dependencies between + - mii->inc_insn's producers and mii->mem_insn as a consumer (if backwards) + - mii->inc_insn's consumers and mii->mem_insn as a producer (if !backwards). +*/ static bool find_inc (struct mem_inc_info *mii, bool backwards) { sd_iterator_def sd_it; dep_t dep; + sd_list_types_def mem_deps = backwards ? SD_LIST_HARD_BACK : SD_LIST_FORW; + int n_mem_deps = sd_lists_size (mii->mem_insn, mem_deps); - sd_it = sd_iterator_start (mii->mem_insn, - backwards ? SD_LIST_HARD_BACK : SD_LIST_FORW); + sd_it = sd_iterator_start (mii->mem_insn, mem_deps); while (sd_iterator_cond (&sd_it, &dep)) { dep_node_t node = DEP_LINK_NODE (*sd_it.linkp); rtx_insn *pro = DEP_PRO (dep); rtx_insn *con = DEP_CON (dep); - rtx_insn *inc_cand = backwards ? pro : con; + rtx_insn *inc_cand; + int n_inc_deps; + if (DEP_NONREG (dep) || DEP_MULTIPLE (dep)) goto next; + + if (backwards) + { + inc_cand = pro; + n_inc_deps = sd_lists_size (inc_cand, SD_LIST_BACK); + } + else + { + inc_cand = con; + n_inc_deps = sd_lists_size (inc_cand, SD_LIST_FORW); + } + + /* In the FOR_EACH_DEP loop below we will create additional n_inc_deps + for mem_insn. This by itself is not a problem, since each mem_insn + will have only a few inc_insns associated with it. However, if + we consider that a single inc_insn may have a lot of mem_insns, AND, + on top of that, a few other inc_insns associated with it -- + those _other inc_insns_ will get (n_mem_deps * number of MEM insns) + dependencies created for them. This may cause an exponential + growth of memory usage and scheduling time. + See PR96388 for details. + We [heuristically] use n_inc_deps as a proxy for the number of MEM + insns, and drop opportunities for breaking modifiable_mem dependencies + when dependency lists grow beyond reasonable size. */ + if (n_mem_deps * n_inc_deps + >= param_max_pending_list_length * param_max_pending_list_length) + goto next; + if (parse_add_or_inc (mii, inc_cand, backwards)) { struct dep_replacement *desc; @@ -4838,6 +4873,11 @@ find_inc (struct mem_inc_info *mii, bool backwards) desc->insn = mii->mem_insn; move_dep_link (DEP_NODE_BACK (node), INSN_HARD_BACK_DEPS (con), INSN_SPEC_BACK_DEPS (con)); + + /* Make sure that n_inc_deps above is consistent with dependencies + we create. */ + gcc_assert (mii->inc_insn == inc_cand); + if (backwards) { FOR_EACH_DEP (mii->inc_insn, SD_LIST_BACK, sd_it, dep)