| /* Basic IPA optimizations and utilities. |
| Copyright (C) 2003-2021 Free Software Foundation, Inc. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify it under |
| the terms of the GNU General Public License as published by the Free |
| Software Foundation; either version 3, or (at your option) any later |
| version. |
| |
| GCC is distributed in the hope that it will be useful, but WITHOUT ANY |
| WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING3. If not see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "backend.h" |
| #include "target.h" |
| #include "tree.h" |
| #include "gimple.h" |
| #include "alloc-pool.h" |
| #include "tree-pass.h" |
| #include "stringpool.h" |
| #include "cgraph.h" |
| #include "gimplify.h" |
| #include "tree-iterator.h" |
| #include "ipa-utils.h" |
| #include "symbol-summary.h" |
| #include "tree-vrp.h" |
| #include "ipa-prop.h" |
| #include "ipa-fnsummary.h" |
| #include "dbgcnt.h" |
| #include "debug.h" |
| #include "stringpool.h" |
| #include "attribs.h" |
| |
| /* Return true when NODE has ADDR reference. */ |
| |
| static bool |
| has_addr_references_p (struct cgraph_node *node, |
| void *) |
| { |
| int i; |
| struct ipa_ref *ref = NULL; |
| |
| for (i = 0; node->iterate_referring (i, ref); i++) |
| if (ref->use == IPA_REF_ADDR) |
| return true; |
| return false; |
| } |
| |
| /* Return true when NODE can be target of an indirect call. */ |
| |
| static bool |
| is_indirect_call_target_p (struct cgraph_node *node, void *) |
| { |
| return node->indirect_call_target; |
| } |
| |
| /* Look for all functions inlined to NODE and update their inlined_to pointers |
| to INLINED_TO. */ |
| |
| static void |
| update_inlined_to_pointer (struct cgraph_node *node, struct cgraph_node *inlined_to) |
| { |
| struct cgraph_edge *e; |
| for (e = node->callees; e; e = e->next_callee) |
| if (e->callee->inlined_to) |
| { |
| e->callee->inlined_to = inlined_to; |
| update_inlined_to_pointer (e->callee, inlined_to); |
| } |
| } |
| |
| /* Add symtab NODE to queue starting at FIRST. |
| |
| The queue is linked via AUX pointers and terminated by pointer to 1. |
| We enqueue nodes at two occasions: when we find them reachable or when we find |
| their bodies needed for further clonning. In the second case we mark them |
| by pointer to 2 after processing so they are re-queue when they become |
| reachable. */ |
| |
| static void |
| enqueue_node (symtab_node *node, symtab_node **first, |
| hash_set<symtab_node *> *reachable) |
| { |
| /* Node is still in queue; do nothing. */ |
| if (node->aux && node->aux != (void *) 2) |
| return; |
| /* Node was already processed as unreachable, re-enqueue |
| only if it became reachable now. */ |
| if (node->aux == (void *)2 && !reachable->contains (node)) |
| return; |
| node->aux = *first; |
| *first = node; |
| } |
| |
| /* Return true if NODE may get inlined later. |
| This is used to keep DECL_EXTERNAL function bodies around long enough |
| so inliner can proces them. */ |
| |
| static bool |
| possible_inline_candidate_p (symtab_node *node) |
| { |
| if (symtab->state >= IPA_SSA_AFTER_INLINING) |
| return false; |
| cgraph_node *cnode = dyn_cast <cgraph_node *> (node); |
| if (!cnode) |
| return false; |
| if (DECL_UNINLINABLE (cnode->decl)) |
| return false; |
| if (opt_for_fn (cnode->decl, optimize)) |
| return true; |
| if (symtab->state >= IPA_SSA) |
| return false; |
| return lookup_attribute ("always_inline", DECL_ATTRIBUTES (node->decl)); |
| } |
| |
| /* Process references. */ |
| |
| static void |
| process_references (symtab_node *snode, |
| symtab_node **first, |
| hash_set<symtab_node *> *reachable) |
| { |
| int i; |
| struct ipa_ref *ref = NULL; |
| for (i = 0; snode->iterate_reference (i, ref); i++) |
| { |
| symtab_node *node = ref->referred; |
| symtab_node *body = node->ultimate_alias_target (); |
| |
| if (node->definition && !node->in_other_partition |
| && ((!DECL_EXTERNAL (node->decl) || node->alias) |
| || (possible_inline_candidate_p (node) |
| /* We use variable constructors during late compilation for |
| constant folding. Keep references alive so partitioning |
| knows about potential references. */ |
| || (VAR_P (node->decl) |
| && (flag_wpa |
| || flag_incremental_link |
| == INCREMENTAL_LINK_LTO) |
| && dyn_cast <varpool_node *> (node) |
| ->ctor_useable_for_folding_p ())))) |
| { |
| /* Be sure that we will not optimize out alias target |
| body. */ |
| if (DECL_EXTERNAL (node->decl) |
| && node->alias |
| && symtab->state < IPA_SSA_AFTER_INLINING) |
| reachable->add (body); |
| reachable->add (node); |
| } |
| enqueue_node (node, first, reachable); |
| } |
| } |
| |
| /* EDGE is an polymorphic call. If BEFORE_INLINING_P is set, mark |
| all its potential targets as reachable to permit later inlining if |
| devirtualization happens. After inlining still keep their declarations |
| around, so we can devirtualize to a direct call. |
| |
| Also try to make trivial devirutalization when no or only one target is |
| possible. */ |
| |
| static void |
| walk_polymorphic_call_targets (hash_set<void *> *reachable_call_targets, |
| struct cgraph_edge *edge, |
| symtab_node **first, |
| hash_set<symtab_node *> *reachable) |
| { |
| unsigned int i; |
| void *cache_token; |
| bool final; |
| vec <cgraph_node *>targets |
| = possible_polymorphic_call_targets |
| (edge, &final, &cache_token); |
| |
| if (!reachable_call_targets->add (cache_token)) |
| { |
| for (i = 0; i < targets.length (); i++) |
| { |
| struct cgraph_node *n = targets[i]; |
| |
| /* Do not bother to mark virtual methods in anonymous namespace; |
| either we will find use of virtual table defining it, or it is |
| unused. */ |
| if (TREE_CODE (TREE_TYPE (n->decl)) == METHOD_TYPE |
| && type_in_anonymous_namespace_p |
| (TYPE_METHOD_BASETYPE (TREE_TYPE (n->decl)))) |
| continue; |
| |
| n->indirect_call_target = true; |
| symtab_node *body = n->function_symbol (); |
| |
| /* Prior inlining, keep alive bodies of possible targets for |
| devirtualization. */ |
| if (n->definition |
| && (possible_inline_candidate_p (body) |
| && opt_for_fn (body->decl, flag_devirtualize))) |
| { |
| /* Be sure that we will not optimize out alias target |
| body. */ |
| if (DECL_EXTERNAL (n->decl) |
| && n->alias |
| && symtab->state < IPA_SSA_AFTER_INLINING) |
| reachable->add (body); |
| reachable->add (n); |
| } |
| /* Even after inlining we want to keep the possible targets in the |
| boundary, so late passes can still produce direct call even if |
| the chance for inlining is lost. */ |
| enqueue_node (n, first, reachable); |
| } |
| } |
| |
| /* Very trivial devirtualization; when the type is |
| final or anonymous (so we know all its derivation) |
| and there is only one possible virtual call target, |
| make the edge direct. */ |
| if (final) |
| { |
| if (targets.length () <= 1 && dbg_cnt (devirt)) |
| { |
| cgraph_node *target, *node = edge->caller; |
| if (targets.length () == 1) |
| target = targets[0]; |
| else |
| target = cgraph_node::get_create |
| (builtin_decl_implicit (BUILT_IN_UNREACHABLE)); |
| |
| if (dump_enabled_p ()) |
| { |
| dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, edge->call_stmt, |
| "devirtualizing call in %s to %s\n", |
| edge->caller->dump_name (), |
| target->dump_name ()); |
| } |
| edge = cgraph_edge::make_direct (edge, target); |
| if (ipa_fn_summaries) |
| ipa_update_overall_fn_summary (node->inlined_to |
| ? node->inlined_to : node); |
| else if (edge->call_stmt) |
| cgraph_edge::redirect_call_stmt_to_callee (edge); |
| } |
| } |
| } |
| |
| /* Perform reachability analysis and reclaim all unreachable nodes. |
| |
| The algorithm is basically mark&sweep but with some extra refinements: |
| |
| - reachable extern inline functions needs special handling; the bodies needs |
| to stay in memory until inlining in hope that they will be inlined. |
| After inlining we release their bodies and turn them into unanalyzed |
| nodes even when they are reachable. |
| |
| - virtual functions are kept in callgraph even if they seem unreachable in |
| hope calls to them will be devirtualized. |
| |
| Again we remove them after inlining. In late optimization some |
| devirtualization may happen, but it is not important since we won't inline |
| the call. In theory early opts and IPA should work out all important cases. |
| |
| - virtual clones needs bodies of their origins for later materialization; |
| this means that we want to keep the body even if the origin is unreachable |
| otherwise. To avoid origin from sitting in the callgraph and being |
| walked by IPA passes, we turn them into unanalyzed nodes with body |
| defined. |
| |
| We maintain set of function declaration where body needs to stay in |
| body_needed_for_clonning |
| |
| Inline clones represent special case: their declaration match the |
| declaration of origin and cgraph_remove_node already knows how to |
| reshape callgraph and preserve body when offline copy of function or |
| inline clone is being removed. |
| |
| - C++ virtual tables keyed to other unit are represented as DECL_EXTERNAL |
| variables with DECL_INITIAL set. We finalize these and keep reachable |
| ones around for constant folding purposes. After inlining we however |
| stop walking their references to let everything static referenced by them |
| to be removed when it is otherwise unreachable. |
| |
| We maintain queue of both reachable symbols (i.e. defined symbols that needs |
| to stay) and symbols that are in boundary (i.e. external symbols referenced |
| by reachable symbols or origins of clones). The queue is represented |
| as linked list by AUX pointer terminated by 1. |
| |
| At the end we keep all reachable symbols. For symbols in boundary we always |
| turn definition into a declaration, but we may keep function body around |
| based on body_needed_for_clonning |
| |
| All symbols that enter the queue have AUX pointer non-zero and are in the |
| boundary. Pointer set REACHABLE is used to track reachable symbols. |
| |
| Every symbol can be visited twice - once as part of boundary and once |
| as real reachable symbol. enqueue_node needs to decide whether the |
| node needs to be re-queued for second processing. For this purpose |
| we set AUX pointer of processed symbols in the boundary to constant 2. */ |
| |
| bool |
| symbol_table::remove_unreachable_nodes (FILE *file) |
| { |
| symtab_node *first = (symtab_node *) (void *) 1; |
| struct cgraph_node *node, *next; |
| varpool_node *vnode, *vnext; |
| bool changed = false; |
| hash_set<symtab_node *> reachable; |
| hash_set<tree> body_needed_for_clonning; |
| hash_set<void *> reachable_call_targets; |
| |
| timevar_push (TV_IPA_UNREACHABLE); |
| build_type_inheritance_graph (); |
| if (file) |
| fprintf (file, "\nReclaiming functions:"); |
| if (flag_checking) |
| { |
| FOR_EACH_FUNCTION (node) |
| gcc_assert (!node->aux); |
| FOR_EACH_VARIABLE (vnode) |
| gcc_assert (!vnode->aux); |
| } |
| /* Mark functions whose bodies are obviously needed. |
| This is mostly when they can be referenced externally. Inline clones |
| are special since their declarations are shared with master clone and thus |
| cgraph_can_remove_if_no_direct_calls_and_refs_p should not be called on them. */ |
| FOR_EACH_FUNCTION (node) |
| { |
| node->used_as_abstract_origin = false; |
| node->indirect_call_target = false; |
| if (node->definition |
| && !node->inlined_to |
| && !node->in_other_partition |
| && !node->can_remove_if_no_direct_calls_and_refs_p ()) |
| { |
| gcc_assert (!node->inlined_to); |
| reachable.add (node); |
| enqueue_node (node, &first, &reachable); |
| } |
| else |
| gcc_assert (!node->aux); |
| } |
| |
| /* Mark variables that are obviously needed. */ |
| FOR_EACH_DEFINED_VARIABLE (vnode) |
| if (!vnode->can_remove_if_no_refs_p() |
| && !vnode->in_other_partition) |
| { |
| reachable.add (vnode); |
| enqueue_node (vnode, &first, &reachable); |
| } |
| |
| /* Perform reachability analysis. */ |
| while (first != (symtab_node *) (void *) 1) |
| { |
| bool in_boundary_p = !reachable.contains (first); |
| symtab_node *node = first; |
| |
| first = (symtab_node *)first->aux; |
| |
| /* If we are processing symbol in boundary, mark its AUX pointer for |
| possible later re-processing in enqueue_node. */ |
| if (in_boundary_p) |
| { |
| node->aux = (void *)2; |
| if (node->alias && node->analyzed) |
| enqueue_node (node->get_alias_target (), &first, &reachable); |
| } |
| else |
| { |
| if (TREE_CODE (node->decl) == FUNCTION_DECL |
| && DECL_ABSTRACT_ORIGIN (node->decl)) |
| { |
| struct cgraph_node *origin_node |
| = cgraph_node::get (DECL_ABSTRACT_ORIGIN (node->decl)); |
| if (origin_node && !origin_node->used_as_abstract_origin) |
| { |
| origin_node->used_as_abstract_origin = true; |
| gcc_assert (!origin_node->prev_sibling_clone); |
| gcc_assert (!origin_node->next_sibling_clone); |
| for (cgraph_node *n = origin_node->clones; n; |
| n = n->next_sibling_clone) |
| if (n->decl == DECL_ABSTRACT_ORIGIN (node->decl)) |
| n->used_as_abstract_origin = true; |
| } |
| } |
| /* If any non-external and non-local symbol in a comdat group is |
| reachable, force all externally visible symbols in the same comdat |
| group to be reachable as well. Comdat-local symbols |
| can be discarded if all uses were inlined. */ |
| if (node->same_comdat_group |
| && node->externally_visible |
| && !DECL_EXTERNAL (node->decl)) |
| { |
| symtab_node *next; |
| for (next = node->same_comdat_group; |
| next != node; |
| next = next->same_comdat_group) |
| if (!next->comdat_local_p () |
| && !DECL_EXTERNAL (next->decl) |
| && !reachable.add (next)) |
| enqueue_node (next, &first, &reachable); |
| } |
| /* Mark references as reachable. */ |
| process_references (node, &first, &reachable); |
| } |
| |
| if (cgraph_node *cnode = dyn_cast <cgraph_node *> (node)) |
| { |
| /* Mark the callees reachable unless they are direct calls to extern |
| inline functions we decided to not inline. */ |
| if (!in_boundary_p) |
| { |
| struct cgraph_edge *e; |
| /* Keep alive possible targets for devirtualization. */ |
| if (opt_for_fn (cnode->decl, optimize) |
| && opt_for_fn (cnode->decl, flag_devirtualize)) |
| { |
| struct cgraph_edge *next; |
| for (e = cnode->indirect_calls; e; e = next) |
| { |
| next = e->next_callee; |
| if (e->indirect_info->polymorphic) |
| walk_polymorphic_call_targets (&reachable_call_targets, |
| e, &first, &reachable); |
| } |
| } |
| for (e = cnode->callees; e; e = e->next_callee) |
| { |
| symtab_node *body = e->callee->function_symbol (); |
| if (e->callee->definition |
| && !e->callee->in_other_partition |
| && (!e->inline_failed |
| || !DECL_EXTERNAL (e->callee->decl) |
| || e->callee->alias |
| || possible_inline_candidate_p (e->callee))) |
| { |
| /* Be sure that we will not optimize out alias target |
| body. */ |
| if (DECL_EXTERNAL (e->callee->decl) |
| && e->callee->alias |
| && symtab->state < IPA_SSA_AFTER_INLINING) |
| reachable.add (body); |
| reachable.add (e->callee); |
| } |
| else if (e->callee->declare_variant_alt |
| && !e->callee->in_other_partition) |
| reachable.add (e->callee); |
| enqueue_node (e->callee, &first, &reachable); |
| } |
| |
| /* When inline clone exists, mark body to be preserved so when removing |
| offline copy of the function we don't kill it. */ |
| if (cnode->inlined_to) |
| body_needed_for_clonning.add (cnode->decl); |
| |
| /* For non-inline clones, force their origins to the boundary and ensure |
| that body is not removed. */ |
| while (cnode->clone_of) |
| { |
| bool noninline = cnode->clone_of->decl != cnode->decl; |
| cnode = cnode->clone_of; |
| if (noninline) |
| { |
| body_needed_for_clonning.add (cnode->decl); |
| enqueue_node (cnode, &first, &reachable); |
| } |
| } |
| |
| } |
| else if (cnode->thunk) |
| enqueue_node (cnode->callees->callee, &first, &reachable); |
| |
| /* If any reachable function has simd clones, mark them as |
| reachable as well. */ |
| if (cnode->simd_clones) |
| { |
| cgraph_node *next; |
| for (next = cnode->simd_clones; |
| next; |
| next = next->simdclone->next_clone) |
| if (in_boundary_p |
| || !reachable.add (next)) |
| enqueue_node (next, &first, &reachable); |
| } |
| } |
| /* When we see constructor of external variable, keep referred nodes in the |
| boundary. This will also hold initializers of the external vars NODE |
| refers to. */ |
| varpool_node *vnode = dyn_cast <varpool_node *> (node); |
| if (vnode |
| && DECL_EXTERNAL (node->decl) |
| && !vnode->alias |
| && in_boundary_p) |
| { |
| struct ipa_ref *ref = NULL; |
| for (int i = 0; node->iterate_reference (i, ref); i++) |
| enqueue_node (ref->referred, &first, &reachable); |
| } |
| } |
| |
| /* Remove unreachable functions. */ |
| for (node = first_function (); node; node = next) |
| { |
| next = next_function (node); |
| |
| /* If node is not needed at all, remove it. */ |
| if (!node->aux) |
| { |
| if (file) |
| fprintf (file, " %s", node->dump_name ()); |
| node->remove (); |
| changed = true; |
| } |
| /* If node is unreachable, remove its body. */ |
| else if (!reachable.contains (node)) |
| { |
| /* We keep definitions of thunks and aliases in the boundary so |
| we can walk to the ultimate alias targets and function symbols |
| reliably. */ |
| if (node->alias || node->thunk) |
| ; |
| else if (!body_needed_for_clonning.contains (node->decl)) |
| { |
| /* Make the node a non-clone so that we do not attempt to |
| materialize it later. */ |
| if (node->clone_of) |
| node->remove_from_clone_tree (); |
| node->release_body (); |
| } |
| else if (!node->clone_of) |
| gcc_assert (in_lto_p || DECL_RESULT (node->decl)); |
| if (node->definition && !node->alias && !node->thunk) |
| { |
| if (file) |
| fprintf (file, " %s", node->dump_name ()); |
| node->body_removed = true; |
| node->analyzed = false; |
| node->definition = false; |
| node->cpp_implicit_alias = false; |
| node->alias = false; |
| node->transparent_alias = false; |
| node->thunk = false; |
| node->weakref = false; |
| /* After early inlining we drop always_inline attributes on |
| bodies of functions that are still referenced (have their |
| address taken). */ |
| DECL_ATTRIBUTES (node->decl) |
| = remove_attribute ("always_inline", |
| DECL_ATTRIBUTES (node->decl)); |
| if (!node->in_other_partition) |
| node->local = false; |
| node->remove_callees (); |
| node->remove_all_references (); |
| changed = true; |
| } |
| } |
| else |
| gcc_assert (node->clone_of || !node->has_gimple_body_p () |
| || in_lto_p || DECL_RESULT (node->decl)); |
| } |
| |
| /* Inline clones might be kept around so their materializing allows further |
| cloning. If the function the clone is inlined into is removed, we need |
| to turn it into normal cone. */ |
| FOR_EACH_FUNCTION (node) |
| { |
| if (node->inlined_to |
| && !node->callers) |
| { |
| gcc_assert (node->clones); |
| node->inlined_to = NULL; |
| update_inlined_to_pointer (node, node); |
| } |
| node->aux = NULL; |
| } |
| |
| /* Remove unreachable variables. */ |
| if (file) |
| fprintf (file, "\nReclaiming variables:"); |
| for (vnode = first_variable (); vnode; vnode = vnext) |
| { |
| vnext = next_variable (vnode); |
| if (!vnode->aux |
| /* For can_refer_decl_in_current_unit_p we want to track for |
| all external variables if they are defined in other partition |
| or not. */ |
| && (!flag_ltrans || !DECL_EXTERNAL (vnode->decl))) |
| { |
| struct ipa_ref *ref = NULL; |
| |
| /* First remove the aliases, so varpool::remove can possibly lookup |
| the constructor and save it for future use. */ |
| while (vnode->iterate_direct_aliases (0, ref)) |
| { |
| if (file) |
| fprintf (file, " %s", ref->referred->dump_name ()); |
| ref->referring->remove (); |
| } |
| if (file) |
| fprintf (file, " %s", vnode->dump_name ()); |
| vnext = next_variable (vnode); |
| /* Signal removal to the debug machinery. */ |
| if (! flag_wpa || flag_incremental_link == INCREMENTAL_LINK_LTO) |
| { |
| vnode->definition = false; |
| (*debug_hooks->late_global_decl) (vnode->decl); |
| } |
| vnode->remove (); |
| changed = true; |
| } |
| else if (!reachable.contains (vnode) && !vnode->alias) |
| { |
| tree init; |
| if (vnode->definition) |
| { |
| if (file) |
| fprintf (file, " %s", vnode->dump_name ()); |
| changed = true; |
| } |
| /* Keep body if it may be useful for constant folding. */ |
| if ((flag_wpa || flag_incremental_link == INCREMENTAL_LINK_LTO) |
| || ((init = ctor_for_folding (vnode->decl)) == error_mark_node)) |
| vnode->remove_initializer (); |
| else |
| DECL_INITIAL (vnode->decl) = init; |
| vnode->body_removed = true; |
| vnode->definition = false; |
| vnode->analyzed = false; |
| vnode->aux = NULL; |
| |
| vnode->remove_from_same_comdat_group (); |
| |
| vnode->remove_all_references (); |
| } |
| else |
| vnode->aux = NULL; |
| } |
| |
| /* Now update address_taken flags and try to promote functions to be local. */ |
| if (file) |
| fprintf (file, "\nClearing address taken flags:"); |
| FOR_EACH_DEFINED_FUNCTION (node) |
| if (node->address_taken |
| && !node->used_from_other_partition) |
| { |
| if (!node->call_for_symbol_and_aliases |
| (has_addr_references_p, NULL, true)) |
| { |
| if (file) |
| fprintf (file, " %s", node->dump_name ()); |
| node->address_taken = false; |
| changed = true; |
| if (node->local_p () |
| /* Virtual functions may be kept in cgraph just because |
| of possible later devirtualization. Do not mark them as |
| local too early so we won't optimize them out before |
| we are done with polymorphic call analysis. */ |
| && (symtab->state >= IPA_SSA_AFTER_INLINING |
| || !node->call_for_symbol_and_aliases |
| (is_indirect_call_target_p, NULL, true))) |
| { |
| node->local = true; |
| if (file) |
| fprintf (file, " (local)"); |
| } |
| } |
| } |
| if (file) |
| fprintf (file, "\n"); |
| |
| symtab_node::checking_verify_symtab_nodes (); |
| |
| /* If we removed something, perhaps profile could be improved. */ |
| if (changed && (optimize || in_lto_p) && ipa_call_summaries) |
| FOR_EACH_DEFINED_FUNCTION (node) |
| ipa_propagate_frequency (node); |
| |
| timevar_pop (TV_IPA_UNREACHABLE); |
| return changed; |
| } |
| |
| /* Process references to VNODE and set flags WRITTEN, ADDRESS_TAKEN, READ |
| as needed, also clear EXPLICIT_REFS if the references to given variable |
| do not need to be explicit. */ |
| |
| void |
| process_references (varpool_node *vnode, |
| bool *written, bool *address_taken, |
| bool *read, bool *explicit_refs) |
| { |
| int i; |
| struct ipa_ref *ref; |
| |
| if (!vnode->all_refs_explicit_p () |
| || TREE_THIS_VOLATILE (vnode->decl)) |
| *explicit_refs = false; |
| |
| for (i = 0; vnode->iterate_referring (i, ref) |
| && *explicit_refs && (!*written || !*address_taken || !*read); i++) |
| switch (ref->use) |
| { |
| case IPA_REF_ADDR: |
| *address_taken = true; |
| break; |
| case IPA_REF_LOAD: |
| *read = true; |
| break; |
| case IPA_REF_STORE: |
| *written = true; |
| break; |
| case IPA_REF_ALIAS: |
| process_references (dyn_cast<varpool_node *> (ref->referring), written, |
| address_taken, read, explicit_refs); |
| break; |
| } |
| } |
| |
| /* Set TREE_READONLY bit. */ |
| |
| bool |
| set_readonly_bit (varpool_node *vnode, void *data ATTRIBUTE_UNUSED) |
| { |
| TREE_READONLY (vnode->decl) = true; |
| return false; |
| } |
| |
| /* Set writeonly bit and clear the initalizer, since it will not be needed. */ |
| |
| bool |
| set_writeonly_bit (varpool_node *vnode, void *data) |
| { |
| vnode->writeonly = true; |
| if (optimize || in_lto_p) |
| { |
| DECL_INITIAL (vnode->decl) = NULL; |
| if (!vnode->alias) |
| { |
| if (vnode->num_references ()) |
| *(bool *)data = true; |
| vnode->remove_all_references (); |
| } |
| } |
| return false; |
| } |
| |
| /* Clear addressale bit of VNODE. */ |
| |
| bool |
| clear_addressable_bit (varpool_node *vnode, void *data ATTRIBUTE_UNUSED) |
| { |
| vnode->address_taken = false; |
| TREE_ADDRESSABLE (vnode->decl) = 0; |
| return false; |
| } |
| |
| /* Discover variables that have no longer address taken, are read-only or |
| write-only and update their flags. |
| |
| Return true when unreachable symbol removal should be done. |
| |
| FIXME: This cannot be done in between gimplify and omp_expand since |
| readonly flag plays role on what is shared and what is not. Currently we do |
| this transformation as part of whole program visibility and re-do at |
| ipa-reference pass (to take into account clonning), but it would |
| make sense to do it before early optimizations. */ |
| |
| bool |
| ipa_discover_variable_flags (void) |
| { |
| if (!flag_ipa_reference_addressable) |
| return false; |
| |
| bool remove_p = false; |
| varpool_node *vnode; |
| if (dump_file) |
| fprintf (dump_file, "Clearing variable flags:"); |
| FOR_EACH_VARIABLE (vnode) |
| if (!vnode->alias |
| && (TREE_ADDRESSABLE (vnode->decl) |
| || !vnode->writeonly |
| || !TREE_READONLY (vnode->decl))) |
| { |
| bool written = false; |
| bool address_taken = false; |
| bool read = false; |
| bool explicit_refs = true; |
| |
| process_references (vnode, &written, &address_taken, &read, |
| &explicit_refs); |
| if (!explicit_refs) |
| continue; |
| if (!address_taken) |
| { |
| if (TREE_ADDRESSABLE (vnode->decl) && dump_file) |
| fprintf (dump_file, " %s (non-addressable)", |
| vnode->dump_name ()); |
| vnode->call_for_symbol_and_aliases (clear_addressable_bit, NULL, |
| true); |
| } |
| if (!address_taken && !written |
| /* Making variable in explicit section readonly can cause section |
| type conflict. |
| See e.g. gcc.c-torture/compile/pr23237.c */ |
| && vnode->get_section () == NULL) |
| { |
| if (!TREE_READONLY (vnode->decl) && dump_file) |
| fprintf (dump_file, " %s (read-only)", vnode->dump_name ()); |
| vnode->call_for_symbol_and_aliases (set_readonly_bit, NULL, true); |
| } |
| if (!vnode->writeonly && !read && !address_taken && written) |
| { |
| if (dump_file) |
| fprintf (dump_file, " %s (write-only)", vnode->dump_name ()); |
| vnode->call_for_symbol_and_aliases (set_writeonly_bit, &remove_p, |
| true); |
| } |
| } |
| if (dump_file) |
| fprintf (dump_file, "\n"); |
| return remove_p; |
| } |
| |
| /* Generate and emit a static constructor or destructor. WHICH must |
| be one of 'I' (for a constructor), 'D' (for a destructor). |
| BODY is a STATEMENT_LIST containing GENERIC |
| statements. PRIORITY is the initialization priority for this |
| constructor or destructor. |
| |
| FINAL specify whether the externally visible name for collect2 should |
| be produced. */ |
| |
| static void |
| cgraph_build_static_cdtor_1 (char which, tree body, int priority, bool final, |
| tree optimization, |
| tree target) |
| { |
| static int counter = 0; |
| char which_buf[16]; |
| tree decl, name, resdecl; |
| |
| /* The priority is encoded in the constructor or destructor name. |
| collect2 will sort the names and arrange that they are called at |
| program startup. */ |
| if (!targetm.have_ctors_dtors && final) |
| { |
| sprintf (which_buf, "%c_%.5d_%d", which, priority, counter++); |
| name = get_file_function_name (which_buf); |
| } |
| else |
| { |
| /* Proudce sane name but one not recognizable by collect2, just for the |
| case we fail to inline the function. */ |
| sprintf (which_buf, "_sub_%c_%.5d_%d", which, priority, counter++); |
| name = get_identifier (which_buf); |
| } |
| |
| decl = build_decl (input_location, FUNCTION_DECL, name, |
| build_function_type_list (void_type_node, NULL_TREE)); |
| current_function_decl = decl; |
| |
| resdecl = build_decl (input_location, |
| RESULT_DECL, NULL_TREE, void_type_node); |
| DECL_ARTIFICIAL (resdecl) = 1; |
| DECL_RESULT (decl) = resdecl; |
| DECL_CONTEXT (resdecl) = decl; |
| |
| allocate_struct_function (decl, false); |
| |
| TREE_STATIC (decl) = 1; |
| TREE_USED (decl) = 1; |
| DECL_FUNCTION_SPECIFIC_OPTIMIZATION (decl) = optimization; |
| DECL_FUNCTION_SPECIFIC_TARGET (decl) = target; |
| DECL_ARTIFICIAL (decl) = 1; |
| DECL_IGNORED_P (decl) = 1; |
| DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (decl) = 1; |
| DECL_SAVED_TREE (decl) = body; |
| if (!targetm.have_ctors_dtors && final) |
| { |
| TREE_PUBLIC (decl) = 1; |
| DECL_PRESERVE_P (decl) = 1; |
| } |
| DECL_UNINLINABLE (decl) = 1; |
| |
| DECL_INITIAL (decl) = make_node (BLOCK); |
| BLOCK_SUPERCONTEXT (DECL_INITIAL (decl)) = decl; |
| TREE_USED (DECL_INITIAL (decl)) = 1; |
| |
| DECL_SOURCE_LOCATION (decl) = input_location; |
| cfun->function_end_locus = input_location; |
| |
| switch (which) |
| { |
| case 'I': |
| DECL_STATIC_CONSTRUCTOR (decl) = 1; |
| decl_init_priority_insert (decl, priority); |
| break; |
| case 'D': |
| DECL_STATIC_DESTRUCTOR (decl) = 1; |
| decl_fini_priority_insert (decl, priority); |
| break; |
| default: |
| gcc_unreachable (); |
| } |
| |
| gimplify_function_tree (decl); |
| |
| cgraph_node::add_new_function (decl, false); |
| |
| set_cfun (NULL); |
| current_function_decl = NULL; |
| } |
| |
| /* Generate and emit a static constructor or destructor. WHICH must |
| be one of 'I' (for a constructor) or 'D' (for a destructor). |
| BODY is a STATEMENT_LIST containing GENERIC |
| statements. PRIORITY is the initialization priority for this |
| constructor or destructor. */ |
| |
| void |
| cgraph_build_static_cdtor (char which, tree body, int priority) |
| { |
| /* FIXME: We should be able to |
| gcc_assert (!in_lto_p); |
| because at LTO time the global options are not safe to use. |
| Unfortunately ASAN finish_file will produce constructors late and they |
| may lead to surprises. */ |
| cgraph_build_static_cdtor_1 (which, body, priority, false, |
| optimization_default_node, |
| target_option_default_node); |
| } |
| |
| /* When target does not have ctors and dtors, we call all constructor |
| and destructor by special initialization/destruction function |
| recognized by collect2. |
| |
| When we are going to build this function, collect all constructors and |
| destructors and turn them into normal functions. */ |
| |
| static void |
| record_cdtor_fn (struct cgraph_node *node, vec<tree> *ctors, vec<tree> *dtors) |
| { |
| if (DECL_STATIC_CONSTRUCTOR (node->decl)) |
| ctors->safe_push (node->decl); |
| if (DECL_STATIC_DESTRUCTOR (node->decl)) |
| dtors->safe_push (node->decl); |
| node = cgraph_node::get (node->decl); |
| DECL_DISREGARD_INLINE_LIMITS (node->decl) = 1; |
| } |
| |
| /* Define global constructors/destructor functions for the CDTORS, of |
| which they are LEN. The CDTORS are sorted by initialization |
| priority. If CTOR_P is true, these are constructors; otherwise, |
| they are destructors. */ |
| |
| static void |
| build_cdtor (bool ctor_p, const vec<tree> &cdtors) |
| { |
| size_t i,j; |
| size_t len = cdtors.length (); |
| |
| i = 0; |
| while (i < len) |
| { |
| tree body; |
| tree fn; |
| priority_type priority; |
| |
| priority = 0; |
| body = NULL_TREE; |
| j = i; |
| do |
| { |
| priority_type p; |
| fn = cdtors[j]; |
| p = ctor_p ? DECL_INIT_PRIORITY (fn) : DECL_FINI_PRIORITY (fn); |
| if (j == i) |
| priority = p; |
| else if (p != priority) |
| break; |
| j++; |
| } |
| while (j < len); |
| |
| /* When there is only one cdtor and target supports them, do nothing. */ |
| if (j == i + 1 |
| && targetm.have_ctors_dtors) |
| { |
| i++; |
| continue; |
| } |
| /* Find the next batch of constructors/destructors with the same |
| initialization priority. */ |
| for (;i < j; i++) |
| { |
| tree call; |
| fn = cdtors[i]; |
| call = build_call_expr (fn, 0); |
| if (ctor_p) |
| DECL_STATIC_CONSTRUCTOR (fn) = 0; |
| else |
| DECL_STATIC_DESTRUCTOR (fn) = 0; |
| /* We do not want to optimize away pure/const calls here. |
| When optimizing, these should be already removed, when not |
| optimizing, we want user to be able to breakpoint in them. */ |
| TREE_SIDE_EFFECTS (call) = 1; |
| append_to_statement_list (call, &body); |
| } |
| gcc_assert (body != NULL_TREE); |
| /* Generate a function to call all the function of like |
| priority. */ |
| cgraph_build_static_cdtor_1 (ctor_p ? 'I' : 'D', body, priority, true, |
| DECL_FUNCTION_SPECIFIC_OPTIMIZATION (cdtors[0]), |
| DECL_FUNCTION_SPECIFIC_TARGET (cdtors[0])); |
| } |
| } |
| |
| /* Comparison function for qsort. P1 and P2 are actually of type |
| "tree *" and point to static constructors. DECL_INIT_PRIORITY is |
| used to determine the sort order. */ |
| |
| static int |
| compare_ctor (const void *p1, const void *p2) |
| { |
| tree f1; |
| tree f2; |
| int priority1; |
| int priority2; |
| |
| f1 = *(const tree *)p1; |
| f2 = *(const tree *)p2; |
| priority1 = DECL_INIT_PRIORITY (f1); |
| priority2 = DECL_INIT_PRIORITY (f2); |
| |
| if (priority1 < priority2) |
| return -1; |
| else if (priority1 > priority2) |
| return 1; |
| else |
| /* Ensure a stable sort. Constructors are executed in backwarding |
| order to make LTO initialize braries first. */ |
| return DECL_UID (f2) - DECL_UID (f1); |
| } |
| |
| /* Comparison function for qsort. P1 and P2 are actually of type |
| "tree *" and point to static destructors. DECL_FINI_PRIORITY is |
| used to determine the sort order. */ |
| |
| static int |
| compare_dtor (const void *p1, const void *p2) |
| { |
| tree f1; |
| tree f2; |
| int priority1; |
| int priority2; |
| |
| f1 = *(const tree *)p1; |
| f2 = *(const tree *)p2; |
| priority1 = DECL_FINI_PRIORITY (f1); |
| priority2 = DECL_FINI_PRIORITY (f2); |
| |
| if (priority1 < priority2) |
| return -1; |
| else if (priority1 > priority2) |
| return 1; |
| else |
| /* Ensure a stable sort. */ |
| return DECL_UID (f1) - DECL_UID (f2); |
| } |
| |
| /* Generate functions to call static constructors and destructors |
| for targets that do not support .ctors/.dtors sections. These |
| functions have magic names which are detected by collect2. */ |
| |
| static void |
| build_cdtor_fns (vec<tree> *ctors, vec<tree> *dtors) |
| { |
| if (!ctors->is_empty ()) |
| { |
| gcc_assert (!targetm.have_ctors_dtors || in_lto_p); |
| ctors->qsort (compare_ctor); |
| build_cdtor (/*ctor_p=*/true, *ctors); |
| } |
| |
| if (!dtors->is_empty ()) |
| { |
| gcc_assert (!targetm.have_ctors_dtors || in_lto_p); |
| dtors->qsort (compare_dtor); |
| build_cdtor (/*ctor_p=*/false, *dtors); |
| } |
| } |
| |
| /* Look for constructors and destructors and produce function calling them. |
| This is needed for targets not supporting ctors or dtors, but we perform the |
| transformation also at linktime to merge possibly numerous |
| constructors/destructors into single function to improve code locality and |
| reduce size. */ |
| |
| static unsigned int |
| ipa_cdtor_merge (void) |
| { |
| /* A vector of FUNCTION_DECLs declared as static constructors. */ |
| auto_vec<tree, 20> ctors; |
| /* A vector of FUNCTION_DECLs declared as static destructors. */ |
| auto_vec<tree, 20> dtors; |
| struct cgraph_node *node; |
| FOR_EACH_DEFINED_FUNCTION (node) |
| if (DECL_STATIC_CONSTRUCTOR (node->decl) |
| || DECL_STATIC_DESTRUCTOR (node->decl)) |
| record_cdtor_fn (node, &ctors, &dtors); |
| build_cdtor_fns (&ctors, &dtors); |
| return 0; |
| } |
| |
| namespace { |
| |
| const pass_data pass_data_ipa_cdtor_merge = |
| { |
| IPA_PASS, /* type */ |
| "cdtor", /* name */ |
| OPTGROUP_NONE, /* optinfo_flags */ |
| TV_CGRAPHOPT, /* tv_id */ |
| 0, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| 0, /* todo_flags_finish */ |
| }; |
| |
| class pass_ipa_cdtor_merge : public ipa_opt_pass_d |
| { |
| public: |
| pass_ipa_cdtor_merge (gcc::context *ctxt) |
| : ipa_opt_pass_d (pass_data_ipa_cdtor_merge, ctxt, |
| NULL, /* generate_summary */ |
| NULL, /* write_summary */ |
| NULL, /* read_summary */ |
| NULL, /* write_optimization_summary */ |
| NULL, /* read_optimization_summary */ |
| NULL, /* stmt_fixup */ |
| 0, /* function_transform_todo_flags_start */ |
| NULL, /* function_transform */ |
| NULL) /* variable_transform */ |
| {} |
| |
| /* opt_pass methods: */ |
| virtual bool gate (function *); |
| virtual unsigned int execute (function *) { return ipa_cdtor_merge (); } |
| |
| }; // class pass_ipa_cdtor_merge |
| |
| bool |
| pass_ipa_cdtor_merge::gate (function *) |
| { |
| /* Perform the pass when we have no ctors/dtors support |
| or at LTO time to merge multiple constructors into single |
| function. */ |
| return !targetm.have_ctors_dtors || in_lto_p; |
| } |
| |
| } // anon namespace |
| |
| ipa_opt_pass_d * |
| make_pass_ipa_cdtor_merge (gcc::context *ctxt) |
| { |
| return new pass_ipa_cdtor_merge (ctxt); |
| } |
| |
| /* Invalid pointer representing BOTTOM for single user dataflow. */ |
| #define BOTTOM ((cgraph_node *)(size_t) 2) |
| |
| /* Meet operation for single user dataflow. |
| Here we want to associate variables with sigle function that may access it. |
| |
| FUNCTION is current single user of a variable, VAR is variable that uses it. |
| Latttice is stored in SINGLE_USER_MAP. |
| |
| We represent: |
| - TOP by no entry in SIGNLE_USER_MAP |
| - BOTTOM by BOTTOM in AUX pointer (to save lookups) |
| - known single user by cgraph pointer in SINGLE_USER_MAP. */ |
| |
| cgraph_node * |
| meet (cgraph_node *function, varpool_node *var, |
| hash_map<varpool_node *, cgraph_node *> &single_user_map) |
| { |
| struct cgraph_node *user, **f; |
| |
| if (var->aux == BOTTOM) |
| return BOTTOM; |
| |
| f = single_user_map.get (var); |
| if (!f) |
| return function; |
| user = *f; |
| if (!function) |
| return user; |
| else if (function != user) |
| return BOTTOM; |
| else |
| return function; |
| } |
| |
| /* Propagation step of single-use dataflow. |
| |
| Check all uses of VNODE and see if they are used by single function FUNCTION. |
| SINGLE_USER_MAP represents the dataflow lattice. */ |
| |
| cgraph_node * |
| propagate_single_user (varpool_node *vnode, cgraph_node *function, |
| hash_map<varpool_node *, cgraph_node *> &single_user_map) |
| { |
| int i; |
| struct ipa_ref *ref; |
| |
| gcc_assert (!vnode->externally_visible); |
| |
| /* If node is an alias, first meet with its target. */ |
| if (vnode->alias) |
| function = meet (function, vnode->get_alias_target (), single_user_map); |
| |
| /* Check all users and see if they correspond to a single function. */ |
| for (i = 0; vnode->iterate_referring (i, ref) && function != BOTTOM; i++) |
| { |
| struct cgraph_node *cnode = dyn_cast <cgraph_node *> (ref->referring); |
| if (cnode) |
| { |
| if (cnode->inlined_to) |
| cnode = cnode->inlined_to; |
| if (!function) |
| function = cnode; |
| else if (function != cnode) |
| function = BOTTOM; |
| } |
| else |
| function = meet (function, dyn_cast <varpool_node *> (ref->referring), |
| single_user_map); |
| } |
| return function; |
| } |
| |
| /* Pass setting used_by_single_function flag. |
| This flag is set on variable when there is only one function that may |
| possibly referr to it. */ |
| |
| static unsigned int |
| ipa_single_use (void) |
| { |
| varpool_node *first = (varpool_node *) (void *) 1; |
| varpool_node *var; |
| hash_map<varpool_node *, cgraph_node *> single_user_map; |
| |
| FOR_EACH_DEFINED_VARIABLE (var) |
| if (!var->all_refs_explicit_p ()) |
| var->aux = BOTTOM; |
| else |
| { |
| /* Enqueue symbol for dataflow. */ |
| var->aux = first; |
| first = var; |
| } |
| |
| /* The actual dataflow. */ |
| |
| while (first != (void *) 1) |
| { |
| cgraph_node *user, *orig_user, **f; |
| |
| var = first; |
| first = (varpool_node *)first->aux; |
| |
| f = single_user_map.get (var); |
| if (f) |
| orig_user = *f; |
| else |
| orig_user = NULL; |
| user = propagate_single_user (var, orig_user, single_user_map); |
| |
| gcc_checking_assert (var->aux != BOTTOM); |
| |
| /* If user differs, enqueue all references. */ |
| if (user != orig_user) |
| { |
| unsigned int i; |
| ipa_ref *ref; |
| |
| single_user_map.put (var, user); |
| |
| /* Enqueue all aliases for re-processing. */ |
| for (i = 0; var->iterate_direct_aliases (i, ref); i++) |
| if (!ref->referring->aux) |
| { |
| ref->referring->aux = first; |
| first = dyn_cast <varpool_node *> (ref->referring); |
| } |
| /* Enqueue all users for re-processing. */ |
| for (i = 0; var->iterate_reference (i, ref); i++) |
| if (!ref->referred->aux |
| && ref->referred->definition |
| && is_a <varpool_node *> (ref->referred)) |
| { |
| ref->referred->aux = first; |
| first = dyn_cast <varpool_node *> (ref->referred); |
| } |
| |
| /* If user is BOTTOM, just punt on this var. */ |
| if (user == BOTTOM) |
| var->aux = BOTTOM; |
| else |
| var->aux = NULL; |
| } |
| else |
| var->aux = NULL; |
| } |
| |
| FOR_EACH_DEFINED_VARIABLE (var) |
| { |
| if (var->aux != BOTTOM) |
| { |
| /* Not having the single user known means that the VAR is |
| unreachable. Either someone forgot to remove unreachable |
| variables or the reachability here is wrong. */ |
| |
| gcc_checking_assert (single_user_map.get (var)); |
| |
| if (dump_file) |
| { |
| fprintf (dump_file, "Variable %s is used by single function\n", |
| var->dump_name ()); |
| } |
| var->used_by_single_function = true; |
| } |
| var->aux = NULL; |
| } |
| return 0; |
| } |
| |
| namespace { |
| |
| const pass_data pass_data_ipa_single_use = |
| { |
| IPA_PASS, /* type */ |
| "single-use", /* name */ |
| OPTGROUP_NONE, /* optinfo_flags */ |
| TV_CGRAPHOPT, /* tv_id */ |
| 0, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| 0, /* todo_flags_finish */ |
| }; |
| |
| class pass_ipa_single_use : public ipa_opt_pass_d |
| { |
| public: |
| pass_ipa_single_use (gcc::context *ctxt) |
| : ipa_opt_pass_d (pass_data_ipa_single_use, ctxt, |
| NULL, /* generate_summary */ |
| NULL, /* write_summary */ |
| NULL, /* read_summary */ |
| NULL, /* write_optimization_summary */ |
| NULL, /* read_optimization_summary */ |
| NULL, /* stmt_fixup */ |
| 0, /* function_transform_todo_flags_start */ |
| NULL, /* function_transform */ |
| NULL) /* variable_transform */ |
| {} |
| |
| /* opt_pass methods: */ |
| virtual unsigned int execute (function *) { return ipa_single_use (); } |
| |
| }; // class pass_ipa_single_use |
| |
| } // anon namespace |
| |
| ipa_opt_pass_d * |
| make_pass_ipa_single_use (gcc::context *ctxt) |
| { |
| return new pass_ipa_single_use (ctxt); |
| } |
| |