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/* Interprocedural constant propagation Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc. Contributed by Razya Ladelsky <RAZYA@il.ibm.com> and Martin Jambor <mjambor@suse.cz> 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/>. */ /* Interprocedural constant propagation (IPA-CP). The goal of this transformation is to 1) discover functions which are always invoked with some arguments with the same known constant values and modify the functions so that the subsequent optimizations can take advantage of the knowledge, and 2) partial specialization - create specialized versions of functions transformed in this way if some parameters are known constants only in certain contexts but the estimated tradeoff between speedup and cost size is deemed good. The algorithm also propagates types and attempts to perform type based devirtualization. Types are propagated much like constants. The algorithm basically consists of three stages. In the first, functions are analyzed one at a time and jump functions are constructed for all known call-sites. In the second phase, the pass propagates information from the jump functions across the call to reveal what values are available at what call sites, performs estimations of effects of known values on functions and their callees, and finally decides what specialized extra versions should be created. In the third, the special versions materialize and appropriate calls are redirected. The algorithm used is to a certain extent based on "Interprocedural Constant Propagation", by David Callahan, Keith D Cooper, Ken Kennedy, Linda Torczon, Comp86, pg 152-161 and "A Methodology for Procedure Cloning" by Keith D Cooper, Mary W. Hall, and Ken Kennedy. First stage - intraprocedural analysis ======================================= This phase computes jump_function and modification flags. A jump function for a call-site represents the values passed as an actual arguments of a given call-site. In principle, there are three types of values: Pass through - the caller's formal parameter is passed as an actual argument, plus an operation on it can be performed. Constant - a constant is passed as an actual argument. Unknown - neither of the above. All jump function types are described in detail in ipa-prop.h, together with the data structures that represent them and methods of accessing them. ipcp_generate_summary() is the main function of the first stage. Second stage - interprocedural analysis ======================================== This stage is itself divided into two phases. In the first, we propagate known values over the call graph, in the second, we make cloning decisions. It uses a different algorithm than the original Callahan's paper. First, we traverse the functions topologically from callers to callees and, for each strongly connected component (SCC), we propagate constants according to previously computed jump functions. We also record what known values depend on other known values and estimate local effects. Finally, we propagate cumulative information about these effects from dependant values to those on which they depend. Second, we again traverse the call graph in the same topological order and make clones for functions which we know are called with the same values in all contexts and decide about extra specialized clones of functions just for some contexts - these decisions are based on both local estimates and cumulative estimates propagated from callees. ipcp_propagate_stage() and ipcp_decision_stage() together constitute the third stage. Third phase - materialization of clones, call statement updates. ============================================ This stage is currently performed by call graph code (mainly in cgraphunit.c and tree-inline.c) according to instructions inserted to the call graph by the second stage. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tree.h" #include "target.h" #include "gimple.h" #include "cgraph.h" #include "ipa-prop.h" #include "tree-flow.h" #include "tree-pass.h" #include "flags.h" #include "timevar.h" #include "diagnostic.h" #include "tree-pretty-print.h" #include "tree-dump.h" #include "tree-inline.h" #include "fibheap.h" #include "params.h" #include "ipa-inline.h" #include "ipa-utils.h" struct ipcp_value; /* Describes a particular source for an IPA-CP value. */ struct ipcp_value_source { /* The incoming edge that brought the value. */ struct cgraph_edge *cs; /* If the jump function that resulted into his value was a pass-through or an ancestor, this is the ipcp_value of the caller from which the described value has been derived. Otherwise it is NULL. */ struct ipcp_value *val; /* Next pointer in a linked list of sources of a value. */ struct ipcp_value_source *next; /* If the jump function that resulted into his value was a pass-through or an ancestor, this is the index of the parameter of the caller the jump function references. */ int index; }; /* Describes one particular value stored in struct ipcp_lattice. */ struct ipcp_value { /* The actual value for the given parameter. This is either an IPA invariant or a TREE_BINFO describing a type that can be used for devirtualization. */ tree value; /* The list of sources from which this value originates. */ struct ipcp_value_source *sources; /* Next pointers in a linked list of all values in a lattice. */ struct ipcp_value *next; /* Next pointers in a linked list of values in a strongly connected component of values. */ struct ipcp_value *scc_next; /* Next pointers in a linked list of SCCs of values sorted topologically according their sources. */ struct ipcp_value *topo_next; /* A specialized node created for this value, NULL if none has been (so far) created. */ struct cgraph_node *spec_node; /* Depth first search number and low link for topological sorting of values. */ int dfs, low_link; /* Time benefit and size cost that specializing the function for this value would bring about in this function alone. */ int local_time_benefit, local_size_cost; /* Time benefit and size cost that specializing the function for this value can bring about in it's callees (transitively). */ int prop_time_benefit, prop_size_cost; /* True if this valye is currently on the topo-sort stack. */ bool on_stack; }; /* Allocation pools for values and their sources in ipa-cp. */ alloc_pool ipcp_values_pool; alloc_pool ipcp_sources_pool; /* Lattice describing potential values of a formal parameter of a function and some of their other properties. TOP is represented by a lattice with zero values and with contains_variable and bottom flags cleared. BOTTOM is represented by a lattice with the bottom flag set. In that case, values and contains_variable flag should be disregarded. */ struct ipcp_lattice { /* The list of known values and types in this lattice. Note that values are not deallocated if a lattice is set to bottom because there may be value sources referencing them. */ struct ipcp_value *values; /* Number of known values and types in this lattice. */ int values_count; /* The lattice contains a variable component (in addition to values). */ bool contains_variable; /* The value of the lattice is bottom (i.e. variable and unusable for any propagation). */ bool bottom; /* There is a virtual call based on this parameter. */ bool virt_call; }; /* Maximal count found in program. */ static gcov_type max_count; /* Original overall size of the program. */ static long overall_size, max_new_size; /* Head of the linked list of topologically sorted values. */ static struct ipcp_value *values_topo; /* Return the lattice corresponding to the Ith formal parameter of the function described by INFO. */ static inline struct ipcp_lattice * ipa_get_lattice (struct ipa_node_params *info, int i) { gcc_assert (i >= 0 && i < ipa_get_param_count (info)); gcc_checking_assert (!info->ipcp_orig_node); gcc_checking_assert (info->lattices); return &(info->lattices[i]); } /* Return whether LAT is a lattice with a single constant and without an undefined value. */ static inline bool ipa_lat_is_single_const (struct ipcp_lattice *lat) { if (lat->bottom || lat->contains_variable || lat->values_count != 1) return false; else return true; } /* Return true iff the CS is an edge within a strongly connected component as computed by ipa_reduced_postorder. */ static inline bool edge_within_scc (struct cgraph_edge *cs) { struct ipa_dfs_info *caller_dfs = (struct ipa_dfs_info *) cs->caller->aux; struct ipa_dfs_info *callee_dfs; struct cgraph_node *callee = cgraph_function_node (cs->callee, NULL); callee_dfs = (struct ipa_dfs_info *) callee->aux; return (caller_dfs && callee_dfs && caller_dfs->scc_no == callee_dfs->scc_no); } /* Print V which is extracted from a value in a lattice to F. */ static void print_ipcp_constant_value (FILE * f, tree v) { if (TREE_CODE (v) == TREE_BINFO) { fprintf (f, "BINFO "); print_generic_expr (f, BINFO_TYPE (v), 0); } else if (TREE_CODE (v) == ADDR_EXPR && TREE_CODE (TREE_OPERAND (v, 0)) == CONST_DECL) { fprintf (f, "& "); print_generic_expr (f, DECL_INITIAL (TREE_OPERAND (v, 0)), 0); } else print_generic_expr (f, v, 0); } /* Print all ipcp_lattices of all functions to F. */ static void print_all_lattices (FILE * f, bool dump_sources, bool dump_benefits) { struct cgraph_node *node; int i, count; fprintf (f, "\nLattices:\n"); FOR_EACH_FUNCTION_WITH_GIMPLE_BODY (node) { struct ipa_node_params *info; info = IPA_NODE_REF (node); fprintf (f, " Node: %s/%i:\n", cgraph_node_name (node), node->uid); count = ipa_get_param_count (info); for (i = 0; i < count; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); struct ipcp_value *val; bool prev = false; fprintf (f, " param [%d]: ", i); if (lat->bottom) { fprintf (f, "BOTTOM\n"); continue; } if (!lat->values_count && !lat->contains_variable) { fprintf (f, "TOP\n"); continue; } if (lat->contains_variable) { fprintf (f, "VARIABLE"); prev = true; if (dump_benefits) fprintf (f, "\n"); } for (val = lat->values; val; val = val->next) { if (dump_benefits && prev) fprintf (f, " "); else if (!dump_benefits && prev) fprintf (f, ", "); else prev = true; print_ipcp_constant_value (f, val->value); if (dump_sources) { struct ipcp_value_source *s; fprintf (f, " [from:"); for (s = val->sources; s; s = s->next) fprintf (f, " %i(%i)", s->cs->caller->uid,s->cs->frequency); fprintf (f, "]"); } if (dump_benefits) fprintf (f, " [loc_time: %i, loc_size: %i, " "prop_time: %i, prop_size: %i]\n", val->local_time_benefit, val->local_size_cost, val->prop_time_benefit, val->prop_size_cost); } if (!dump_benefits) fprintf (f, "\n"); } } } /* Determine whether it is at all technically possible to create clones of NODE and store this information in the ipa_node_params structure associated with NODE. */ static void determine_versionability (struct cgraph_node *node) { const char *reason = NULL; /* There are a number of generic reasons functions cannot be versioned. We also cannot remove parameters if there are type attributes such as fnspec present. */ if (node->alias || node->thunk.thunk_p) reason = "alias or thunk"; else if (!node->local.versionable) reason = "not a tree_versionable_function"; else if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE) reason = "insufficient body availability"; if (reason && dump_file && !node->alias && !node->thunk.thunk_p) fprintf (dump_file, "Function %s/%i is not versionable, reason: %s.\n", cgraph_node_name (node), node->uid, reason); node->local.versionable = (reason == NULL); } /* Return true if it is at all technically possible to create clones of a NODE. */ static bool ipcp_versionable_function_p (struct cgraph_node *node) { return node->local.versionable; } /* Structure holding accumulated information about callers of a node. */ struct caller_statistics { gcov_type count_sum; int n_calls, n_hot_calls, freq_sum; }; /* Initialize fields of STAT to zeroes. */ static inline void init_caller_stats (struct caller_statistics *stats) { stats->count_sum = 0; stats->n_calls = 0; stats->n_hot_calls = 0; stats->freq_sum = 0; } /* Worker callback of cgraph_for_node_and_aliases accumulating statistics of non-thunk incoming edges to NODE. */ static bool gather_caller_stats (struct cgraph_node *node, void *data) { struct caller_statistics *stats = (struct caller_statistics *) data; struct cgraph_edge *cs; for (cs = node->callers; cs; cs = cs->next_caller) if (cs->caller->thunk.thunk_p) cgraph_for_node_and_aliases (cs->caller, gather_caller_stats, stats, false); else { stats->count_sum += cs->count; stats->freq_sum += cs->frequency; stats->n_calls++; if (cgraph_maybe_hot_edge_p (cs)) stats->n_hot_calls ++; } return false; } /* Return true if this NODE is viable candidate for cloning. */ static bool ipcp_cloning_candidate_p (struct cgraph_node *node) { struct caller_statistics stats; gcc_checking_assert (cgraph_function_with_gimple_body_p (node)); if (!flag_ipa_cp_clone) { if (dump_file) fprintf (dump_file, "Not considering %s for cloning; " "-fipa-cp-clone disabled.\n", cgraph_node_name (node)); return false; } if (!optimize_function_for_speed_p (DECL_STRUCT_FUNCTION (node->decl))) { if (dump_file) fprintf (dump_file, "Not considering %s for cloning; " "optimizing it for size.\n", cgraph_node_name (node)); return false; } init_caller_stats (&stats); cgraph_for_node_and_aliases (node, gather_caller_stats, &stats, false); if (inline_summary (node)->self_size < stats.n_calls) { if (dump_file) fprintf (dump_file, "Considering %s for cloning; code might shrink.\n", cgraph_node_name (node)); return true; } /* When profile is available and function is hot, propagate into it even if calls seems cold; constant propagation can improve function's speed significantly. */ if (max_count) { if (stats.count_sum > node->count * 90 / 100) { if (dump_file) fprintf (dump_file, "Considering %s for cloning; " "usually called directly.\n", cgraph_node_name (node)); return true; } } if (!stats.n_hot_calls) { if (dump_file) fprintf (dump_file, "Not considering %s for cloning; no hot calls.\n", cgraph_node_name (node)); return false; } if (dump_file) fprintf (dump_file, "Considering %s for cloning.\n", cgraph_node_name (node)); return true; } /* Arrays representing a topological ordering of call graph nodes and a stack of noes used during constant propagation. */ struct topo_info { struct cgraph_node **order; struct cgraph_node **stack; int nnodes, stack_top; }; /* Allocate the arrays in TOPO and topologically sort the nodes into order. */ static void build_toporder_info (struct topo_info *topo) { topo->order = XCNEWVEC (struct cgraph_node *, cgraph_n_nodes); topo->stack = XCNEWVEC (struct cgraph_node *, cgraph_n_nodes); topo->stack_top = 0; topo->nnodes = ipa_reduced_postorder (topo->order, true, true, NULL); } /* Free information about strongly connected components and the arrays in TOPO. */ static void free_toporder_info (struct topo_info *topo) { ipa_free_postorder_info (); free (topo->order); free (topo->stack); } /* Add NODE to the stack in TOPO, unless it is already there. */ static inline void push_node_to_stack (struct topo_info *topo, struct cgraph_node *node) { struct ipa_node_params *info = IPA_NODE_REF (node); if (info->node_enqueued) return; info->node_enqueued = 1; topo->stack[topo->stack_top++] = node; } /* Pop a node from the stack in TOPO and return it or return NULL if the stack is empty. */ static struct cgraph_node * pop_node_from_stack (struct topo_info *topo) { if (topo->stack_top) { struct cgraph_node *node; topo->stack_top--; node = topo->stack[topo->stack_top]; IPA_NODE_REF (node)->node_enqueued = 0; return node; } else return NULL; } /* Set lattice LAT to bottom and return true if it previously was not set as such. */ static inline bool set_lattice_to_bottom (struct ipcp_lattice *lat) { bool ret = !lat->bottom; lat->bottom = true; return ret; } /* Mark lattice as containing an unknown value and return true if it previously was not marked as such. */ static inline bool set_lattice_contains_variable (struct ipcp_lattice *lat) { bool ret = !lat->contains_variable; lat->contains_variable = true; return ret; } /* Initialize ipcp_lattices. */ static void initialize_node_lattices (struct cgraph_node *node) { struct ipa_node_params *info = IPA_NODE_REF (node); struct cgraph_edge *ie; bool disable = false, variable = false; int i; gcc_checking_assert (cgraph_function_with_gimple_body_p (node)); if (!node->local.local) { /* When cloning is allowed, we can assume that externally visible functions are not called. We will compensate this by cloning later. */ if (ipcp_versionable_function_p (node) && ipcp_cloning_candidate_p (node)) variable = true; else disable = true; } if (disable || variable) { for (i = 0; i < ipa_get_param_count (info) ; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); if (disable) set_lattice_to_bottom (lat); else set_lattice_contains_variable (lat); } if (dump_file && (dump_flags & TDF_DETAILS) && node->alias && node->thunk.thunk_p) fprintf (dump_file, "Marking all lattices of %s/%i as %s\n", cgraph_node_name (node), node->uid, disable ? "BOTTOM" : "VARIABLE"); } for (ie = node->indirect_calls; ie; ie = ie->next_callee) if (ie->indirect_info->polymorphic) { gcc_checking_assert (ie->indirect_info->param_index >= 0); ipa_get_lattice (info, ie->indirect_info->param_index)->virt_call = 1; } } /* Return the result of a (possibly arithmetic) pass through jump function JFUNC on the constant value INPUT. Return NULL_TREE if that cannot be determined or itself is considered an interprocedural invariant. */ static tree ipa_get_jf_pass_through_result (struct ipa_jump_func *jfunc, tree input) { tree restype, res; gcc_checking_assert (is_gimple_ip_invariant (input)); if (jfunc->value.pass_through.operation == NOP_EXPR) return input; if (TREE_CODE_CLASS (jfunc->value.pass_through.operation) == tcc_comparison) restype = boolean_type_node; else restype = TREE_TYPE (input); res = fold_binary (jfunc->value.pass_through.operation, restype, input, jfunc->value.pass_through.operand); if (res && !is_gimple_ip_invariant (res)) return NULL_TREE; return res; } /* Return the result of an ancestor jump function JFUNC on the constant value INPUT. Return NULL_TREE if that cannot be determined. */ static tree ipa_get_jf_ancestor_result (struct ipa_jump_func *jfunc, tree input) { if (TREE_CODE (input) == ADDR_EXPR) { tree t = TREE_OPERAND (input, 0); t = build_ref_for_offset (EXPR_LOCATION (t), t, jfunc->value.ancestor.offset, jfunc->value.ancestor.type, NULL, false); return build_fold_addr_expr (t); } else return NULL_TREE; } /* Extract the acual BINFO being described by JFUNC which must be a known type jump function. */ static tree ipa_value_from_known_type_jfunc (struct ipa_jump_func *jfunc) { tree base_binfo = TYPE_BINFO (jfunc->value.known_type.base_type); if (!base_binfo) return NULL_TREE; return get_binfo_at_offset (base_binfo, jfunc->value.known_type.offset, jfunc->value.known_type.component_type); } /* Determine whether JFUNC evaluates to a known value (that is either a constant or a binfo) and if so, return it. Otherwise return NULL. INFO describes the caller node so that pass-through jump functions can be evaluated. */ tree ipa_value_from_jfunc (struct ipa_node_params *info, struct ipa_jump_func *jfunc) { if (jfunc->type == IPA_JF_CONST) return jfunc->value.constant; else if (jfunc->type == IPA_JF_KNOWN_TYPE) return ipa_value_from_known_type_jfunc (jfunc); else if (jfunc->type == IPA_JF_PASS_THROUGH || jfunc->type == IPA_JF_ANCESTOR) { tree input; int idx; if (jfunc->type == IPA_JF_PASS_THROUGH) idx = jfunc->value.pass_through.formal_id; else idx = jfunc->value.ancestor.formal_id; if (info->ipcp_orig_node) input = VEC_index (tree, info->known_vals, idx); else { struct ipcp_lattice *lat; if (!info->lattices) { gcc_checking_assert (!flag_ipa_cp); return NULL_TREE; } lat = ipa_get_lattice (info, idx); if (!ipa_lat_is_single_const (lat)) return NULL_TREE; input = lat->values->value; } if (!input) return NULL_TREE; if (jfunc->type == IPA_JF_PASS_THROUGH) { if (jfunc->value.pass_through.operation == NOP_EXPR) return input; else if (TREE_CODE (input) == TREE_BINFO) return NULL_TREE; else return ipa_get_jf_pass_through_result (jfunc, input); } else { if (TREE_CODE (input) == TREE_BINFO) return get_binfo_at_offset (input, jfunc->value.ancestor.offset, jfunc->value.ancestor.type); else return ipa_get_jf_ancestor_result (jfunc, input); } } else return NULL_TREE; } /* If checking is enabled, verify that no lattice is in the TOP state, i.e. not bottom, not containing a variable component and without any known value at the same time. */ DEBUG_FUNCTION void ipcp_verify_propagated_values (void) { struct cgraph_node *node; FOR_EACH_FUNCTION_WITH_GIMPLE_BODY (node) { struct ipa_node_params *info = IPA_NODE_REF (node); int i, count = ipa_get_param_count (info); for (i = 0; i < count; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); if (!lat->bottom && !lat->contains_variable && lat->values_count == 0) { if (dump_file) { fprintf (dump_file, "\nIPA lattices after constant " "propagation:\n"); print_all_lattices (dump_file, true, false); } gcc_unreachable (); } } } } /* Return true iff X and Y should be considered equal values by IPA-CP. */ static bool values_equal_for_ipcp_p (tree x, tree y) { gcc_checking_assert (x != NULL_TREE && y != NULL_TREE); if (x == y) return true; if (TREE_CODE (x) == TREE_BINFO || TREE_CODE (y) == TREE_BINFO) return false; if (TREE_CODE (x) == ADDR_EXPR && TREE_CODE (y) == ADDR_EXPR && TREE_CODE (TREE_OPERAND (x, 0)) == CONST_DECL && TREE_CODE (TREE_OPERAND (y, 0)) == CONST_DECL) return operand_equal_p (DECL_INITIAL (TREE_OPERAND (x, 0)), DECL_INITIAL (TREE_OPERAND (y, 0)), 0); else return operand_equal_p (x, y, 0); } /* Add a new value source to VAL, marking that a value comes from edge CS and (if the underlying jump function is a pass-through or an ancestor one) from a caller value SRC_VAL of a caller parameter described by SRC_INDEX. */ static void add_value_source (struct ipcp_value *val, struct cgraph_edge *cs, struct ipcp_value *src_val, int src_idx) { struct ipcp_value_source *src; src = (struct ipcp_value_source *) pool_alloc (ipcp_sources_pool); src->cs = cs; src->val = src_val; src->index = src_idx; src->next = val->sources; val->sources = src; } /* Try to add NEWVAL to LAT, potentially creating a new struct ipcp_value for it. CS, SRC_VAL and SRC_INDEX are meant for add_value_source and have the same meaning. */ static bool add_value_to_lattice (struct ipcp_lattice *lat, tree newval, struct cgraph_edge *cs, struct ipcp_value *src_val, int src_idx) { struct ipcp_value *val; if (lat->bottom) return false; for (val = lat->values; val; val = val->next) if (values_equal_for_ipcp_p (val->value, newval)) { if (edge_within_scc (cs)) { struct ipcp_value_source *s; for (s = val->sources; s ; s = s->next) if (s->cs == cs) break; if (s) return false; } add_value_source (val, cs, src_val, src_idx); return false; } if (lat->values_count == PARAM_VALUE (PARAM_IPA_CP_VALUE_LIST_SIZE)) { /* We can only free sources, not the values themselves, because sources of other values in this this SCC might point to them. */ for (val = lat->values; val; val = val->next) { while (val->sources) { struct ipcp_value_source *src = val->sources; val->sources = src->next; pool_free (ipcp_sources_pool, src); } } lat->values = NULL; return set_lattice_to_bottom (lat); } lat->values_count++; val = (struct ipcp_value *) pool_alloc (ipcp_values_pool); memset (val, 0, sizeof (*val)); add_value_source (val, cs, src_val, src_idx); val->value = newval; val->next = lat->values; lat->values = val; return true; } /* Propagate values through a pass-through jump function JFUNC associated with edge CS, taking values from SRC_LAT and putting them into DEST_LAT. SRC_IDX is the index of the source parameter. */ static bool propagate_vals_accross_pass_through (struct cgraph_edge *cs, struct ipa_jump_func *jfunc, struct ipcp_lattice *src_lat, struct ipcp_lattice *dest_lat, int src_idx) { struct ipcp_value *src_val; bool ret = false; if (jfunc->value.pass_through.operation == NOP_EXPR) for (src_val = src_lat->values; src_val; src_val = src_val->next) ret |= add_value_to_lattice (dest_lat, src_val->value, cs, src_val, src_idx); /* Do not create new values when propagating within an SCC because if there arithmetic functions with circular dependencies, there is infinite number of them and we would just make lattices bottom. */ else if (edge_within_scc (cs)) ret = set_lattice_contains_variable (dest_lat); else for (src_val = src_lat->values; src_val; src_val = src_val->next) { tree cstval = src_val->value; if (TREE_CODE (cstval) == TREE_BINFO) { ret |= set_lattice_contains_variable (dest_lat); continue; } cstval = ipa_get_jf_pass_through_result (jfunc, cstval); if (cstval) ret |= add_value_to_lattice (dest_lat, cstval, cs, src_val, src_idx); else ret |= set_lattice_contains_variable (dest_lat); } return ret; } /* Propagate values through an ancestor jump function JFUNC associated with edge CS, taking values from SRC_LAT and putting them into DEST_LAT. SRC_IDX is the index of the source parameter. */ static bool propagate_vals_accross_ancestor (struct cgraph_edge *cs, struct ipa_jump_func *jfunc, struct ipcp_lattice *src_lat, struct ipcp_lattice *dest_lat, int src_idx) { struct ipcp_value *src_val; bool ret = false; if (edge_within_scc (cs)) return set_lattice_contains_variable (dest_lat); for (src_val = src_lat->values; src_val; src_val = src_val->next) { tree t = src_val->value; if (TREE_CODE (t) == TREE_BINFO) t = get_binfo_at_offset (t, jfunc->value.ancestor.offset, jfunc->value.ancestor.type); else t = ipa_get_jf_ancestor_result (jfunc, t); if (t) ret |= add_value_to_lattice (dest_lat, t, cs, src_val, src_idx); else ret |= set_lattice_contains_variable (dest_lat); } return ret; } /* Propagate values across jump function JFUNC that is associated with edge CS and put the values into DEST_LAT. */ static bool propagate_accross_jump_function (struct cgraph_edge *cs, struct ipa_jump_func *jfunc, struct ipcp_lattice *dest_lat) { if (dest_lat->bottom) return false; if (jfunc->type == IPA_JF_CONST || jfunc->type == IPA_JF_KNOWN_TYPE) { tree val; if (jfunc->type == IPA_JF_KNOWN_TYPE) { val = ipa_value_from_known_type_jfunc (jfunc); if (!val) return set_lattice_contains_variable (dest_lat); } else val = jfunc->value.constant; return add_value_to_lattice (dest_lat, val, cs, NULL, 0); } else if (jfunc->type == IPA_JF_PASS_THROUGH || jfunc->type == IPA_JF_ANCESTOR) { struct ipa_node_params *caller_info = IPA_NODE_REF (cs->caller); struct ipcp_lattice *src_lat; int src_idx; bool ret; if (jfunc->type == IPA_JF_PASS_THROUGH) src_idx = jfunc->value.pass_through.formal_id; else src_idx = jfunc->value.ancestor.formal_id; src_lat = ipa_get_lattice (caller_info, src_idx); if (src_lat->bottom) return set_lattice_contains_variable (dest_lat); /* If we would need to clone the caller and cannot, do not propagate. */ if (!ipcp_versionable_function_p (cs->caller) && (src_lat->contains_variable || (src_lat->values_count > 1))) return set_lattice_contains_variable (dest_lat); if (jfunc->type == IPA_JF_PASS_THROUGH) ret = propagate_vals_accross_pass_through (cs, jfunc, src_lat, dest_lat, src_idx); else ret = propagate_vals_accross_ancestor (cs, jfunc, src_lat, dest_lat, src_idx); if (src_lat->contains_variable) ret |= set_lattice_contains_variable (dest_lat); return ret; } /* TODO: We currently do not handle member method pointers in IPA-CP (we only use it for indirect inlining), we should propagate them too. */ return set_lattice_contains_variable (dest_lat); } /* Propagate constants from the caller to the callee of CS. INFO describes the caller. */ static bool propagate_constants_accross_call (struct cgraph_edge *cs) { struct ipa_node_params *callee_info; enum availability availability; struct cgraph_node *callee, *alias_or_thunk; struct ipa_edge_args *args; bool ret = false; int i, args_count, parms_count; callee = cgraph_function_node (cs->callee, &availability); if (!callee->analyzed) return false; gcc_checking_assert (cgraph_function_with_gimple_body_p (callee)); callee_info = IPA_NODE_REF (callee); args = IPA_EDGE_REF (cs); args_count = ipa_get_cs_argument_count (args); parms_count = ipa_get_param_count (callee_info); /* If this call goes through a thunk we must not propagate to the first (0th) parameter. However, we might need to uncover a thunk from below a series of aliases first. */ alias_or_thunk = cs->callee; while (alias_or_thunk->alias) alias_or_thunk = cgraph_alias_aliased_node (alias_or_thunk); if (alias_or_thunk->thunk.thunk_p) { ret |= set_lattice_contains_variable (ipa_get_lattice (callee_info, 0)); i = 1; } else i = 0; for (; (i < args_count) && (i < parms_count); i++) { struct ipa_jump_func *jump_func = ipa_get_ith_jump_func (args, i); struct ipcp_lattice *dest_lat = ipa_get_lattice (callee_info, i); if (availability == AVAIL_OVERWRITABLE) ret |= set_lattice_contains_variable (dest_lat); else ret |= propagate_accross_jump_function (cs, jump_func, dest_lat); } for (; i < parms_count; i++) ret |= set_lattice_contains_variable (ipa_get_lattice (callee_info, i)); return ret; } /* If an indirect edge IE can be turned into a direct one based on KNOWN_VALS (which can contain both constants and binfos) or KNOWN_BINFOS (which can be NULL) return the destination. */ tree ipa_get_indirect_edge_target (struct cgraph_edge *ie, VEC (tree, heap) *known_vals, VEC (tree, heap) *known_binfos) { int param_index = ie->indirect_info->param_index; HOST_WIDE_INT token, anc_offset; tree otr_type; tree t; if (param_index == -1) return NULL_TREE; if (!ie->indirect_info->polymorphic) { tree t = (VEC_length (tree, known_vals) > (unsigned int) param_index ? VEC_index (tree, known_vals, param_index) : NULL); if (t && TREE_CODE (t) == ADDR_EXPR && TREE_CODE (TREE_OPERAND (t, 0)) == FUNCTION_DECL) return TREE_OPERAND (t, 0); else return NULL_TREE; } token = ie->indirect_info->otr_token; anc_offset = ie->indirect_info->anc_offset; otr_type = ie->indirect_info->otr_type; t = VEC_index (tree, known_vals, param_index); if (!t && known_binfos && VEC_length (tree, known_binfos) > (unsigned int) param_index) t = VEC_index (tree, known_binfos, param_index); if (!t) return NULL_TREE; if (TREE_CODE (t) != TREE_BINFO) { tree binfo; binfo = gimple_extract_devirt_binfo_from_cst (t); if (!binfo) return NULL_TREE; binfo = get_binfo_at_offset (binfo, anc_offset, otr_type); if (!binfo) return NULL_TREE; return gimple_get_virt_method_for_binfo (token, binfo); } else { tree binfo; binfo = get_binfo_at_offset (t, anc_offset, otr_type); if (!binfo) return NULL_TREE; return gimple_get_virt_method_for_binfo (token, binfo); } } /* Calculate devirtualization time bonus for NODE, assuming we know KNOWN_CSTS and KNOWN_BINFOS. */ static int devirtualization_time_bonus (struct cgraph_node *node, VEC (tree, heap) *known_csts, VEC (tree, heap) *known_binfos) { struct cgraph_edge *ie; int res = 0; for (ie = node->indirect_calls; ie; ie = ie->next_callee) { struct cgraph_node *callee; struct inline_summary *isummary; tree target; target = ipa_get_indirect_edge_target (ie, known_csts, known_binfos); if (!target) continue; /* Only bare minimum benefit for clearly un-inlineable targets. */ res += 1; callee = cgraph_get_node (target); if (!callee || !callee->analyzed) continue; isummary = inline_summary (callee); if (!isummary->inlinable) continue; /* FIXME: The values below need re-considering and perhaps also integrating into the cost metrics, at lest in some very basic way. */ if (isummary->size <= MAX_INLINE_INSNS_AUTO / 4) res += 31; else if (isummary->size <= MAX_INLINE_INSNS_AUTO / 2) res += 15; else if (isummary->size <= MAX_INLINE_INSNS_AUTO || DECL_DECLARED_INLINE_P (callee->decl)) res += 7; } return res; } /* Return true if cloning NODE is a good idea, given the estimated TIME_BENEFIT and SIZE_COST and with the sum of frequencies of incoming edges to the potential new clone in FREQUENCIES. */ static bool good_cloning_opportunity_p (struct cgraph_node *node, int time_benefit, int freq_sum, gcov_type count_sum, int size_cost) { if (time_benefit == 0 || !flag_ipa_cp_clone || !optimize_function_for_speed_p (DECL_STRUCT_FUNCTION (node->decl))) return false; gcc_assert (size_cost > 0); if (max_count) { int factor = (count_sum * 1000) / max_count; HOST_WIDEST_INT evaluation = (((HOST_WIDEST_INT) time_benefit * factor) / size_cost); if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " good_cloning_opportunity_p (time: %i, " "size: %i, count_sum: " HOST_WIDE_INT_PRINT_DEC ") -> evaluation: " HOST_WIDEST_INT_PRINT_DEC ", threshold: %i\n", time_benefit, size_cost, (HOST_WIDE_INT) count_sum, evaluation, 500); return evaluation >= PARAM_VALUE (PARAM_IPA_CP_EVAL_THRESHOLD); } else { HOST_WIDEST_INT evaluation = (((HOST_WIDEST_INT) time_benefit * freq_sum) / size_cost); if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " good_cloning_opportunity_p (time: %i, " "size: %i, freq_sum: %i) -> evaluation: " HOST_WIDEST_INT_PRINT_DEC ", threshold: %i\n", time_benefit, size_cost, freq_sum, evaluation, CGRAPH_FREQ_BASE /2); return evaluation >= PARAM_VALUE (PARAM_IPA_CP_EVAL_THRESHOLD); } } /* Allocate KNOWN_CSTS and KNOWN_BINFOS and populate them with values of parameters that are known independent of the context. INFO describes the function. If REMOVABLE_PARAMS_COST is non-NULL, the movement cost of all removable parameters will be stored in it. */ static bool gather_context_independent_values (struct ipa_node_params *info, VEC (tree, heap) **known_csts, VEC (tree, heap) **known_binfos, int *removable_params_cost) { int i, count = ipa_get_param_count (info); bool ret = false; *known_csts = NULL; *known_binfos = NULL; VEC_safe_grow_cleared (tree, heap, *known_csts, count); VEC_safe_grow_cleared (tree, heap, *known_binfos, count); if (removable_params_cost) *removable_params_cost = 0; for (i = 0; i < count ; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); if (ipa_lat_is_single_const (lat)) { struct ipcp_value *val = lat->values; if (TREE_CODE (val->value) != TREE_BINFO) { VEC_replace (tree, *known_csts, i, val->value); if (removable_params_cost) *removable_params_cost += estimate_move_cost (TREE_TYPE (val->value)); ret = true; } else if (lat->virt_call) { VEC_replace (tree, *known_binfos, i, val->value); ret = true; } else if (removable_params_cost && !ipa_is_param_used (info, i)) *removable_params_cost += estimate_move_cost (TREE_TYPE (ipa_get_param (info, i))); } else if (removable_params_cost && !ipa_is_param_used (info, i)) *removable_params_cost += estimate_move_cost (TREE_TYPE (ipa_get_param (info, i))); } return ret; } /* Iterate over known values of parameters of NODE and estimate the local effects in terms of time and size they have. */ static void estimate_local_effects (struct cgraph_node *node) { struct ipa_node_params *info = IPA_NODE_REF (node); int i, count = ipa_get_param_count (info); VEC (tree, heap) *known_csts, *known_binfos; bool always_const; int base_time = inline_summary (node)->time; int removable_params_cost; if (!count || !ipcp_versionable_function_p (node)) return; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "\nEstimating effects for %s/%i, base_time: %i.\n", cgraph_node_name (node), node->uid, base_time); always_const = gather_context_independent_values (info, &known_csts, &known_binfos, &removable_params_cost); if (always_const) { struct caller_statistics stats; int time, size; init_caller_stats (&stats); cgraph_for_node_and_aliases (node, gather_caller_stats, &stats, false); estimate_ipcp_clone_size_and_time (node, known_csts, known_binfos, &size, &time); time -= devirtualization_time_bonus (node, known_csts, known_binfos); time -= removable_params_cost; size -= stats.n_calls * removable_params_cost; if (dump_file) fprintf (dump_file, " - context independent values, size: %i, " "time_benefit: %i\n", size, base_time - time); if (size <= 0 || cgraph_will_be_removed_from_program_if_no_direct_calls (node)) { info->clone_for_all_contexts = true; base_time = time; if (dump_file) fprintf (dump_file, " Decided to specialize for all " "known contexts, code not going to grow.\n"); } else if (good_cloning_opportunity_p (node, base_time - time, stats.freq_sum, stats.count_sum, size)) { if (size + overall_size <= max_new_size) { info->clone_for_all_contexts = true; base_time = time; overall_size += size; if (dump_file) fprintf (dump_file, " Decided to specialize for all " "known contexts, growth deemed beneficial.\n"); } else if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " Not cloning for all contexts because " "max_new_size would be reached with %li.\n", size + overall_size); } } for (i = 0; i < count ; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); struct ipcp_value *val; int emc; if (lat->bottom || !lat->values || VEC_index (tree, known_csts, i) || VEC_index (tree, known_binfos, i)) continue; for (val = lat->values; val; val = val->next) { int time, size, time_benefit; if (TREE_CODE (val->value) != TREE_BINFO) { VEC_replace (tree, known_csts, i, val->value); VEC_replace (tree, known_binfos, i, NULL_TREE); emc = estimate_move_cost (TREE_TYPE (val->value)); } else if (lat->virt_call) { VEC_replace (tree, known_csts, i, NULL_TREE); VEC_replace (tree, known_binfos, i, val->value); emc = 0; } else continue; estimate_ipcp_clone_size_and_time (node, known_csts, known_binfos, &size, &time); time_benefit = base_time - time + devirtualization_time_bonus (node, known_csts, known_binfos) + removable_params_cost + emc; gcc_checking_assert (size >=0); /* The inliner-heuristics based estimates may think that in certain contexts some functions do not have any size at all but we want all specializations to have at least a tiny cost, not least not to divide by zero. */ if (size == 0) size = 1; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, " - estimates for value "); print_ipcp_constant_value (dump_file, val->value); fprintf (dump_file, " for parameter "); print_generic_expr (dump_file, ipa_get_param (info, i), 0); fprintf (dump_file, ": time_benefit: %i, size: %i\n", time_benefit, size); } val->local_time_benefit = time_benefit; val->local_size_cost = size; } } VEC_free (tree, heap, known_csts); VEC_free (tree, heap, known_binfos); } /* Add value CUR_VAL and all yet-unsorted values it is dependent on to the topological sort of values. */ static void add_val_to_toposort (struct ipcp_value *cur_val) { static int dfs_counter = 0; static struct ipcp_value *stack; struct ipcp_value_source *src; if (cur_val->dfs) return; dfs_counter++; cur_val->dfs = dfs_counter; cur_val->low_link = dfs_counter; cur_val->topo_next = stack; stack = cur_val; cur_val->on_stack = true; for (src = cur_val->sources; src; src = src->next) if (src->val) { if (src->val->dfs == 0) { add_val_to_toposort (src->val); if (src->val->low_link < cur_val->low_link) cur_val->low_link = src->val->low_link; } else if (src->val->on_stack && src->val->dfs < cur_val->low_link) cur_val->low_link = src->val->dfs; } if (cur_val->dfs == cur_val->low_link) { struct ipcp_value *v, *scc_list = NULL; do { v = stack; stack = v->topo_next; v->on_stack = false; v->scc_next = scc_list; scc_list = v; } while (v != cur_val); cur_val->topo_next = values_topo; values_topo = cur_val; } } /* Add all values in lattices associated with NODE to the topological sort if they are not there yet. */ static void add_all_node_vals_to_toposort (struct cgraph_node *node) { struct ipa_node_params *info = IPA_NODE_REF (node); int i, count = ipa_get_param_count (info); for (i = 0; i < count ; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); struct ipcp_value *val; if (lat->bottom || !lat->values) continue; for (val = lat->values; val; val = val->next) add_val_to_toposort (val); } } /* One pass of constants propagation along the call graph edges, from callers to callees (requires topological ordering in TOPO), iterate over strongly connected components. */ static void propagate_constants_topo (struct topo_info *topo) { int i; for (i = topo->nnodes - 1; i >= 0; i--) { struct cgraph_node *v, *node = topo->order[i]; struct ipa_dfs_info *node_dfs_info; if (!cgraph_function_with_gimple_body_p (node)) continue; node_dfs_info = (struct ipa_dfs_info *) node->aux; /* First, iteratively propagate within the strongly connected component until all lattices stabilize. */ v = node_dfs_info->next_cycle; while (v) { push_node_to_stack (topo, v); v = ((struct ipa_dfs_info *) v->aux)->next_cycle; } v = node; while (v) { struct cgraph_edge *cs; for (cs = v->callees; cs; cs = cs->next_callee) if (edge_within_scc (cs) && propagate_constants_accross_call (cs)) push_node_to_stack (topo, cs->callee); v = pop_node_from_stack (topo); } /* Afterwards, propagate along edges leading out of the SCC, calculates the local effects of the discovered constants and all valid values to their topological sort. */ v = node; while (v) { struct cgraph_edge *cs; estimate_local_effects (v); add_all_node_vals_to_toposort (v); for (cs = v->callees; cs; cs = cs->next_callee) if (!edge_within_scc (cs)) propagate_constants_accross_call (cs); v = ((struct ipa_dfs_info *) v->aux)->next_cycle; } } } /* Return the sum of A and B if none of them is bigger than INT_MAX/2, return the bigger one if otherwise. */ static int safe_add (int a, int b) { if (a > INT_MAX/2 || b > INT_MAX/2) return a > b ? a : b; else return a + b; } /* Propagate the estimated effects of individual values along the topological from the dependant values to those they depend on. */ static void propagate_effects (void) { struct ipcp_value *base; for (base = values_topo; base; base = base->topo_next) { struct ipcp_value_source *src; struct ipcp_value *val; int time = 0, size = 0; for (val = base; val; val = val->scc_next) { time = safe_add (time, val->local_time_benefit + val->prop_time_benefit); size = safe_add (size, val->local_size_cost + val->prop_size_cost); } for (val = base; val; val = val->scc_next) for (src = val->sources; src; src = src->next) if (src->val && cgraph_maybe_hot_edge_p (src->cs)) { src->val->prop_time_benefit = safe_add (time, src->val->prop_time_benefit); src->val->prop_size_cost = safe_add (size, src->val->prop_size_cost); } } } /* Propagate constants, binfos and their effects from the summaries interprocedurally. */ static void ipcp_propagate_stage (struct topo_info *topo) { struct cgraph_node *node; if (dump_file) fprintf (dump_file, "\n Propagating constants:\n\n"); if (in_lto_p) ipa_update_after_lto_read (); FOR_EACH_DEFINED_FUNCTION (node) { struct ipa_node_params *info = IPA_NODE_REF (node); determine_versionability (node); if (cgraph_function_with_gimple_body_p (node)) { info->lattices = XCNEWVEC (struct ipcp_lattice, ipa_get_param_count (info)); initialize_node_lattices (node); } if (node->count > max_count) max_count = node->count; overall_size += inline_summary (node)->self_size; } max_new_size = overall_size; if (max_new_size < PARAM_VALUE (PARAM_LARGE_UNIT_INSNS)) max_new_size = PARAM_VALUE (PARAM_LARGE_UNIT_INSNS); max_new_size += max_new_size * PARAM_VALUE (PARAM_IPCP_UNIT_GROWTH) / 100 + 1; if (dump_file) fprintf (dump_file, "\noverall_size: %li, max_new_size: %li\n", overall_size, max_new_size); propagate_constants_topo (topo); #ifdef ENABLE_CHECKING ipcp_verify_propagated_values (); #endif propagate_effects (); if (dump_file) { fprintf (dump_file, "\nIPA lattices after all propagation:\n"); print_all_lattices (dump_file, (dump_flags & TDF_DETAILS), true); } } /* Discover newly direct outgoing edges from NODE which is a new clone with known KNOWN_VALS and make them direct. */ static void ipcp_discover_new_direct_edges (struct cgraph_node *node, VEC (tree, heap) *known_vals) { struct cgraph_edge *ie, *next_ie; for (ie = node->indirect_calls; ie; ie = next_ie) { tree target; next_ie = ie->next_callee; target = ipa_get_indirect_edge_target (ie, known_vals, NULL); if (target) ipa_make_edge_direct_to_target (ie, target); } } /* Vector of pointers which for linked lists of clones of an original crgaph edge. */ static VEC (cgraph_edge_p, heap) *next_edge_clone; static inline void grow_next_edge_clone_vector (void) { if (VEC_length (cgraph_edge_p, next_edge_clone) <= (unsigned) cgraph_edge_max_uid) VEC_safe_grow_cleared (cgraph_edge_p, heap, next_edge_clone, cgraph_edge_max_uid + 1); } /* Edge duplication hook to grow the appropriate linked list in next_edge_clone. */ static void ipcp_edge_duplication_hook (struct cgraph_edge *src, struct cgraph_edge *dst, __attribute__((unused)) void *data) { grow_next_edge_clone_vector (); VEC_replace (cgraph_edge_p, next_edge_clone, dst->uid, VEC_index (cgraph_edge_p, next_edge_clone, src->uid)); VEC_replace (cgraph_edge_p, next_edge_clone, src->uid, dst); } /* Get the next clone in the linked list of clones of an edge. */ static inline struct cgraph_edge * get_next_cgraph_edge_clone (struct cgraph_edge *cs) { return VEC_index (cgraph_edge_p, next_edge_clone, cs->uid); } /* Return true if edge CS does bring about the value described by SRC. */ static bool cgraph_edge_brings_value_p (struct cgraph_edge *cs, struct ipcp_value_source *src) { struct ipa_node_params *caller_info = IPA_NODE_REF (cs->caller); if (IPA_NODE_REF (cs->callee)->ipcp_orig_node || caller_info->node_dead) return false; if (!src->val) return true; if (caller_info->ipcp_orig_node) { tree t = VEC_index (tree, caller_info->known_vals, src->index); return (t != NULL_TREE && values_equal_for_ipcp_p (src->val->value, t)); } else { struct ipcp_lattice *lat = ipa_get_lattice (caller_info, src->index); if (ipa_lat_is_single_const (lat) && values_equal_for_ipcp_p (src->val->value, lat->values->value)) return true; else return false; } } /* Given VAL, iterate over all its sources and if they still hold, add their edge frequency and their number into *FREQUENCY and *CALLER_COUNT respectively. */ static bool get_info_about_necessary_edges (struct ipcp_value *val, int *freq_sum, gcov_type *count_sum, int *caller_count) { struct ipcp_value_source *src; int freq = 0, count = 0; gcov_type cnt = 0; bool hot = false; for (src = val->sources; src; src = src->next) { struct cgraph_edge *cs = src->cs; while (cs) { if (cgraph_edge_brings_value_p (cs, src)) { count++; freq += cs->frequency; cnt += cs->count; hot |= cgraph_maybe_hot_edge_p (cs); } cs = get_next_cgraph_edge_clone (cs); } } *freq_sum = freq; *count_sum = cnt; *caller_count = count; return hot; } /* Return a vector of incoming edges that do bring value VAL. It is assumed their number is known and equal to CALLER_COUNT. */ static VEC (cgraph_edge_p,heap) * gather_edges_for_value (struct ipcp_value *val, int caller_count) { struct ipcp_value_source *src; VEC (cgraph_edge_p,heap) *ret; ret = VEC_alloc (cgraph_edge_p, heap, caller_count); for (src = val->sources; src; src = src->next) { struct cgraph_edge *cs = src->cs; while (cs) { if (cgraph_edge_brings_value_p (cs, src)) VEC_quick_push (cgraph_edge_p, ret, cs); cs = get_next_cgraph_edge_clone (cs); } } return ret; } /* Construct a replacement map for a know VALUE for a formal parameter PARAM. Return it or NULL if for some reason it cannot be created. */ static struct ipa_replace_map * get_replacement_map (tree value, tree parm) { tree req_type = TREE_TYPE (parm); struct ipa_replace_map *replace_map; if (!useless_type_conversion_p (req_type, TREE_TYPE (value))) { if (fold_convertible_p (req_type, value)) value = fold_build1 (NOP_EXPR, req_type, value); else if (TYPE_SIZE (req_type) == TYPE_SIZE (TREE_TYPE (value))) value = fold_build1 (VIEW_CONVERT_EXPR, req_type, value); else { if (dump_file) { fprintf (dump_file, " const "); print_generic_expr (dump_file, value, 0); fprintf (dump_file, " can't be converted to param "); print_generic_expr (dump_file, parm, 0); fprintf (dump_file, "\n"); } return NULL; } } replace_map = ggc_alloc_ipa_replace_map (); if (dump_file) { fprintf (dump_file, " replacing param "); print_generic_expr (dump_file, parm, 0); fprintf (dump_file, " with const "); print_generic_expr (dump_file, value, 0); fprintf (dump_file, "\n"); } replace_map->old_tree = parm; replace_map->new_tree = value; replace_map->replace_p = true; replace_map->ref_p = false; return replace_map; } /* Dump new profiling counts */ static void dump_profile_updates (struct cgraph_node *orig_node, struct cgraph_node *new_node) { struct cgraph_edge *cs; fprintf (dump_file, " setting count of the specialized node to " HOST_WIDE_INT_PRINT_DEC "\n", (HOST_WIDE_INT) new_node->count); for (cs = new_node->callees; cs ; cs = cs->next_callee) fprintf (dump_file, " edge to %s has count " HOST_WIDE_INT_PRINT_DEC "\n", cgraph_node_name (cs->callee), (HOST_WIDE_INT) cs->count); fprintf (dump_file, " setting count of the original node to " HOST_WIDE_INT_PRINT_DEC "\n", (HOST_WIDE_INT) orig_node->count); for (cs = orig_node->callees; cs ; cs = cs->next_callee) fprintf (dump_file, " edge to %s is left with " HOST_WIDE_INT_PRINT_DEC "\n", cgraph_node_name (cs->callee), (HOST_WIDE_INT) cs->count); } /* After a specialized NEW_NODE version of ORIG_NODE has been created, update their profile information to reflect this. */ static void update_profiling_info (struct cgraph_node *orig_node, struct cgraph_node *new_node) { struct cgraph_edge *cs; struct caller_statistics stats; gcov_type new_sum, orig_sum; gcov_type remainder, orig_node_count = orig_node->count; if (orig_node_count == 0) return; init_caller_stats (&stats); cgraph_for_node_and_aliases (orig_node, gather_caller_stats, &stats, false); orig_sum = stats.count_sum; init_caller_stats (&stats); cgraph_for_node_and_aliases (new_node, gather_caller_stats, &stats, false); new_sum = stats.count_sum; if (orig_node_count < orig_sum + new_sum) { if (dump_file) fprintf (dump_file, " Problem: node %s/%i has too low count " HOST_WIDE_INT_PRINT_DEC " while the sum of incoming " "counts is " HOST_WIDE_INT_PRINT_DEC "\n", cgraph_node_name (orig_node), orig_node->uid, (HOST_WIDE_INT) orig_node_count, (HOST_WIDE_INT) (orig_sum + new_sum)); orig_node_count = (orig_sum + new_sum) * 12 / 10; if (dump_file) fprintf (dump_file, " proceeding by pretending it was " HOST_WIDE_INT_PRINT_DEC "\n", (HOST_WIDE_INT) orig_node_count); } new_node->count = new_sum; remainder = orig_node_count - new_sum; orig_node->count = remainder; for (cs = new_node->callees; cs ; cs = cs->next_callee) if (cs->frequency) cs->count = cs->count * (new_sum * REG_BR_PROB_BASE / orig_node_count) / REG_BR_PROB_BASE; else cs->count = 0; for (cs = orig_node->callees; cs ; cs = cs->next_callee) cs->count = cs->count * (remainder * REG_BR_PROB_BASE / orig_node_count) / REG_BR_PROB_BASE; if (dump_file) dump_profile_updates (orig_node, new_node); } /* Update the respective profile of specialized NEW_NODE and the original ORIG_NODE after additional edges with cumulative count sum REDIRECTED_SUM have been redirected to the specialized version. */ static void update_specialized_profile (struct cgraph_node *new_node, struct cgraph_node *orig_node, gcov_type redirected_sum) { struct cgraph_edge *cs; gcov_type new_node_count, orig_node_count = orig_node->count; if (dump_file) fprintf (dump_file, " the sum of counts of redirected edges is " HOST_WIDE_INT_PRINT_DEC "\n", (HOST_WIDE_INT) redirected_sum); if (orig_node_count == 0) return; gcc_assert (orig_node_count >= redirected_sum); new_node_count = new_node->count; new_node->count += redirected_sum; orig_node->count -= redirected_sum; for (cs = new_node->callees; cs ; cs = cs->next_callee) if (cs->frequency) cs->count += cs->count * redirected_sum / new_node_count; else cs->count = 0; for (cs = orig_node->callees; cs ; cs = cs->next_callee) { gcov_type dec = cs->count * (redirected_sum * REG_BR_PROB_BASE / orig_node_count) / REG_BR_PROB_BASE; if (dec < cs->count) cs->count -= dec; else cs->count = 0; } if (dump_file) dump_profile_updates (orig_node, new_node); } /* Create a specialized version of NODE with known constants and types of parameters in KNOWN_VALS and redirect all edges in CALLERS to it. */ static struct cgraph_node * create_specialized_node (struct cgraph_node *node, VEC (tree, heap) *known_vals, VEC (cgraph_edge_p,heap) *callers) { struct ipa_node_params *new_info, *info = IPA_NODE_REF (node); VEC (ipa_replace_map_p,gc)* replace_trees = NULL; struct cgraph_node *new_node; int i, count = ipa_get_param_count (info); bitmap args_to_skip; gcc_assert (!info->ipcp_orig_node); if (node->local.can_change_signature) { args_to_skip = BITMAP_GGC_ALLOC (); for (i = 0; i < count; i++) { tree t = VEC_index (tree, known_vals, i); if ((t && TREE_CODE (t) != TREE_BINFO) || !ipa_is_param_used (info, i)) bitmap_set_bit (args_to_skip, i); } } else { args_to_skip = NULL; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " cannot change function signature\n"); } for (i = 0; i < count ; i++) { tree t = VEC_index (tree, known_vals, i); if (t && TREE_CODE (t) != TREE_BINFO) { struct ipa_replace_map *replace_map; replace_map = get_replacement_map (t, ipa_get_param (info, i)); if (replace_map) VEC_safe_push (ipa_replace_map_p, gc, replace_trees, replace_map); } } new_node = cgraph_create_virtual_clone (node, callers, replace_trees, args_to_skip, "constprop"); if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " the new node is %s/%i.\n", cgraph_node_name (new_node), new_node->uid); gcc_checking_assert (ipa_node_params_vector && (VEC_length (ipa_node_params_t, ipa_node_params_vector) > (unsigned) cgraph_max_uid)); update_profiling_info (node, new_node); new_info = IPA_NODE_REF (new_node); new_info->ipcp_orig_node = node; new_info->known_vals = known_vals; ipcp_discover_new_direct_edges (new_node, known_vals); VEC_free (cgraph_edge_p, heap, callers); return new_node; } /* Given a NODE, and a subset of its CALLERS, try to populate blanks slots in KNOWN_VALS with constants and types that are also known for all of the CALLERS. */ static void find_more_values_for_callers_subset (struct cgraph_node *node, VEC (tree, heap) *known_vals, VEC (cgraph_edge_p,heap) *callers) { struct ipa_node_params *info = IPA_NODE_REF (node); int i, count = ipa_get_param_count (info); for (i = 0; i < count ; i++) { struct cgraph_edge *cs; tree newval = NULL_TREE; int j; if (ipa_get_lattice (info, i)->bottom || VEC_index (tree, known_vals, i)) continue; FOR_EACH_VEC_ELT (cgraph_edge_p, callers, j, cs) { struct ipa_jump_func *jump_func; tree t; if (i >= ipa_get_cs_argument_count (IPA_EDGE_REF (cs))) { newval = NULL_TREE; break; } jump_func = ipa_get_ith_jump_func (IPA_EDGE_REF (cs), i); t = ipa_value_from_jfunc (IPA_NODE_REF (cs->caller), jump_func); if (!t || (newval && !values_equal_for_ipcp_p (t, newval))) { newval = NULL_TREE; break; } else newval = t; } if (newval) { if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, " adding an extra known value "); print_ipcp_constant_value (dump_file, newval); fprintf (dump_file, " for parameter "); print_generic_expr (dump_file, ipa_get_param (info, i), 0); fprintf (dump_file, "\n"); } VEC_replace (tree, known_vals, i, newval); } } } /* Given an original NODE and a VAL for which we have already created a specialized clone, look whether there are incoming edges that still lead into the old node but now also bring the requested value and also conform to all other criteria such that they can be redirected the the special node. This function can therefore redirect the final edge in a SCC. */ static void perhaps_add_new_callers (struct cgraph_node *node, struct ipcp_value *val) { struct ipa_node_params *dest_info = IPA_NODE_REF (val->spec_node); struct ipcp_value_source *src; int count = ipa_get_param_count (dest_info); gcov_type redirected_sum = 0; for (src = val->sources; src; src = src->next) { struct cgraph_edge *cs = src->cs; while (cs) { enum availability availability; bool insufficient = false; if (cgraph_function_node (cs->callee, &availability) == node && availability > AVAIL_OVERWRITABLE && cgraph_edge_brings_value_p (cs, src)) { struct ipa_node_params *caller_info; struct ipa_edge_args *args; int i; caller_info = IPA_NODE_REF (cs->caller); args = IPA_EDGE_REF (cs); for (i = 0; i < count; i++) { struct ipa_jump_func *jump_func; tree val, t; val = VEC_index (tree, dest_info->known_vals, i); if (!val) continue; if (i >= ipa_get_cs_argument_count (args)) { insufficient = true; break; } jump_func = ipa_get_ith_jump_func (args, i); t = ipa_value_from_jfunc (caller_info, jump_func); if (!t || !values_equal_for_ipcp_p (val, t)) { insufficient = true; break; } } if (!insufficient) { if (dump_file) fprintf (dump_file, " - adding an extra caller %s/%i" " of %s/%i\n", cgraph_node_name (cs->caller), cs->caller->uid, cgraph_node_name (val->spec_node), val->spec_node->uid); cgraph_redirect_edge_callee (cs, val->spec_node); redirected_sum += cs->count; } } cs = get_next_cgraph_edge_clone (cs); } } if (redirected_sum) update_specialized_profile (val->spec_node, node, redirected_sum); } /* Copy KNOWN_BINFOS to KNOWN_VALS. */ static void move_binfos_to_values (VEC (tree, heap) *known_vals, VEC (tree, heap) *known_binfos) { tree t; int i; for (i = 0; VEC_iterate (tree, known_binfos, i, t); i++) if (t) VEC_replace (tree, known_vals, i, t); } /* Decide whether and what specialized clones of NODE should be created. */ static bool decide_whether_version_node (struct cgraph_node *node) { struct ipa_node_params *info = IPA_NODE_REF (node); int i, count = ipa_get_param_count (info); VEC (tree, heap) *known_csts, *known_binfos; bool ret = false; if (count == 0) return false; if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, "\nEvaluating opportunities for %s/%i.\n", cgraph_node_name (node), node->uid); gather_context_independent_values (info, &known_csts, &known_binfos, NULL); for (i = 0; i < count ; i++) { struct ipcp_lattice *lat = ipa_get_lattice (info, i); struct ipcp_value *val; if (lat->bottom || VEC_index (tree, known_csts, i) || VEC_index (tree, known_binfos, i)) continue; for (val = lat->values; val; val = val->next) { int freq_sum, caller_count; gcov_type count_sum; VEC (cgraph_edge_p, heap) *callers; VEC (tree, heap) *kv; if (val->spec_node) { perhaps_add_new_callers (node, val); continue; } else if (val->local_size_cost + overall_size > max_new_size) { if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " Ignoring candidate value because " "max_new_size would be reached with %li.\n", val->local_size_cost + overall_size); continue; } else if (!get_info_about_necessary_edges (val, &freq_sum, &count_sum, &caller_count)) continue; if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, " - considering value "); print_ipcp_constant_value (dump_file, val->value); fprintf (dump_file, " for parameter "); print_generic_expr (dump_file, ipa_get_param (info, i), 0); fprintf (dump_file, " (caller_count: %i)\n", caller_count); } if (!good_cloning_opportunity_p (node, val->local_time_benefit, freq_sum, count_sum, val->local_size_cost) && !good_cloning_opportunity_p (node, val->local_time_benefit + val->prop_time_benefit, freq_sum, count_sum, val->local_size_cost + val->prop_size_cost)) continue; if (dump_file) fprintf (dump_file, " Creating a specialized node of %s/%i.\n", cgraph_node_name (node), node->uid); callers = gather_edges_for_value (val, caller_count); kv = VEC_copy (tree, heap, known_csts); move_binfos_to_values (kv, known_binfos); VEC_replace (tree, kv, i, val->value); find_more_values_for_callers_subset (node, kv, callers); val->spec_node = create_specialized_node (node, kv, callers); overall_size += val->local_size_cost; info = IPA_NODE_REF (node); /* TODO: If for some lattice there is only one other known value left, make a special node for it too. */ ret = true; VEC_replace (tree, kv, i, val->value); } } if (info->clone_for_all_contexts) { VEC (cgraph_edge_p, heap) *callers; if (dump_file) fprintf (dump_file, " - Creating a specialized node of %s/%i " "for all known contexts.\n", cgraph_node_name (node), node->uid); callers = collect_callers_of_node (node); move_binfos_to_values (known_csts, known_binfos); create_specialized_node (node, known_csts, callers); info = IPA_NODE_REF (node); info->clone_for_all_contexts = false; ret = true; } else VEC_free (tree, heap, known_csts); VEC_free (tree, heap, known_binfos); return ret; } /* Transitively mark all callees of NODE within the same SCC as not dead. */ static void spread_undeadness (struct cgraph_node *node) { struct cgraph_edge *cs; for (cs = node->callees; cs; cs = cs->next_callee) if (edge_within_scc (cs)) { struct cgraph_node *callee; struct ipa_node_params *info; callee = cgraph_function_node (cs->callee, NULL); info = IPA_NODE_REF (callee); if (info->node_dead) { info->node_dead = 0; spread_undeadness (callee); } } } /* Return true if NODE has a caller from outside of its SCC that is not dead. Worker callback for cgraph_for_node_and_aliases. */ static bool has_undead_caller_from_outside_scc_p (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED) { struct cgraph_edge *cs; for (cs = node->callers; cs; cs = cs->next_caller) if (cs->caller->thunk.thunk_p && cgraph_for_node_and_aliases (cs->caller, has_undead_caller_from_outside_scc_p, NULL, true)) return true; else if (!edge_within_scc (cs) && !IPA_NODE_REF (cs->caller)->node_dead) return true; return false; } /* Identify nodes within the same SCC as NODE which are no longer needed because of new clones and will be removed as unreachable. */ static void identify_dead_nodes (struct cgraph_node *node) { struct cgraph_node *v; for (v = node; v ; v = ((struct ipa_dfs_info *) v->aux)->next_cycle) if (cgraph_will_be_removed_from_program_if_no_direct_calls (v) && !cgraph_for_node_and_aliases (v, has_undead_caller_from_outside_scc_p, NULL, true)) IPA_NODE_REF (v)->node_dead = 1; for (v = node; v ; v = ((struct ipa_dfs_info *) v->aux)->next_cycle) if (!IPA_NODE_REF (v)->node_dead) spread_undeadness (v); if (dump_file && (dump_flags & TDF_DETAILS)) { for (v = node; v ; v = ((struct ipa_dfs_info *) v->aux)->next_cycle) if (IPA_NODE_REF (v)->node_dead) fprintf (dump_file, " Marking node as dead: %s/%i.\n", cgraph_node_name (v), v->uid); } } /* The decision stage. Iterate over the topological order of call graph nodes TOPO and make specialized clones if deemed beneficial. */ static void ipcp_decision_stage (struct topo_info *topo) { int i; if (dump_file) fprintf (dump_file, "\nIPA decision stage:\n\n"); for (i = topo->nnodes - 1; i >= 0; i--) { struct cgraph_node *node = topo->order[i]; bool change = false, iterate = true; while (iterate) { struct cgraph_node *v; iterate = false; for (v = node; v ; v = ((struct ipa_dfs_info *) v->aux)->next_cycle) if (cgraph_function_with_gimple_body_p (v) && ipcp_versionable_function_p (v)) iterate |= decide_whether_version_node (v); change |= iterate; } if (change) identify_dead_nodes (node); } } /* The IPCP driver. */ static unsigned int ipcp_driver (void) { struct cgraph_2edge_hook_list *edge_duplication_hook_holder; struct topo_info topo; cgraph_remove_unreachable_nodes (true,dump_file); ipa_check_create_node_params (); ipa_check_create_edge_args (); grow_next_edge_clone_vector (); edge_duplication_hook_holder = cgraph_add_edge_duplication_hook (&ipcp_edge_duplication_hook, NULL); ipcp_values_pool = create_alloc_pool ("IPA-CP values", sizeof (struct ipcp_value), 32); ipcp_sources_pool = create_alloc_pool ("IPA-CP value sources", sizeof (struct ipcp_value_source), 64); if (dump_file) { fprintf (dump_file, "\nIPA structures before propagation:\n"); if (dump_flags & TDF_DETAILS) ipa_print_all_params (dump_file); ipa_print_all_jump_functions (dump_file); } /* Topological sort. */ build_toporder_info (&topo); /* Do the interprocedural propagation. */ ipcp_propagate_stage (&topo); /* Decide what constant propagation and cloning should be performed. */ ipcp_decision_stage (&topo); /* Free all IPCP structures. */ free_toporder_info (&topo); VEC_free (cgraph_edge_p, heap, next_edge_clone); cgraph_remove_edge_duplication_hook (edge_duplication_hook_holder); ipa_free_all_structures_after_ipa_cp (); if (dump_file) fprintf (dump_file, "\nIPA constant propagation end\n"); return 0; } /* Initialization and computation of IPCP data structures. This is the initial intraprocedural analysis of functions, which gathers information to be propagated later on. */ static void ipcp_generate_summary (void) { struct cgraph_node *node; if (dump_file) fprintf (dump_file, "\nIPA constant propagation start:\n"); ipa_register_cgraph_hooks (); FOR_EACH_FUNCTION_WITH_GIMPLE_BODY (node) { /* Unreachable nodes should have been eliminated before ipcp. */ gcc_assert (node->needed || node->reachable); node->local.versionable = tree_versionable_function_p (node->decl); ipa_analyze_node (node); } } /* Write ipcp summary for nodes in SET. */ static void ipcp_write_summary (cgraph_node_set set, varpool_node_set vset ATTRIBUTE_UNUSED) { ipa_prop_write_jump_functions (set); } /* Read ipcp summary. */ static void ipcp_read_summary (void) { ipa_prop_read_jump_functions (); } /* Gate for IPCP optimization. */ static bool cgraph_gate_cp (void) { /* FIXME: We should remove the optimize check after we ensure we never run IPA passes when not optimizing. */ return flag_ipa_cp && optimize; } struct ipa_opt_pass_d pass_ipa_cp = { { IPA_PASS, "cp", /* name */ cgraph_gate_cp, /* gate */ ipcp_driver, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_IPA_CONSTANT_PROP, /* tv_id */ 0, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_dump_cgraph | TODO_remove_functions | TODO_ggc_collect /* todo_flags_finish */ }, ipcp_generate_summary, /* generate_summary */ ipcp_write_summary, /* write_summary */ ipcp_read_summary, /* read_summary */ NULL, /* write_optimization_summary */ NULL, /* read_optimization_summary */ NULL, /* stmt_fixup */ 0, /* TODOs */ NULL, /* function_transform */ NULL, /* variable_transform */ };
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