From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- gcc/varpool.c | 727 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 727 insertions(+) create mode 100644 gcc/varpool.c (limited to 'gcc/varpool.c') diff --git a/gcc/varpool.c b/gcc/varpool.c new file mode 100644 index 000000000..5d0eb6893 --- /dev/null +++ b/gcc/varpool.c @@ -0,0 +1,727 @@ +/* Callgraph handling code. + Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2010, 2011 + Free Software Foundation, Inc. + Contributed by Jan Hubicka + +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 +. */ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "tm.h" +#include "tree.h" +#include "cgraph.h" +#include "langhooks.h" +#include "diagnostic-core.h" +#include "hashtab.h" +#include "ggc.h" +#include "timevar.h" +#include "debug.h" +#include "target.h" +#include "output.h" +#include "gimple.h" +#include "tree-flow.h" +#include "flags.h" + +/* This file contains basic routines manipulating variable pool. + + Varpool acts as interface in between the front-end and middle-end + and drives the decision process on what variables and when are + going to be compiled. + + The varpool nodes are allocated lazily for declarations + either by frontend or at callgraph construction time. + All variables supposed to be output into final file needs to be + explicitly marked by frontend via VARPOOL_FINALIZE_DECL function. */ + +/* Hash table used to convert declarations into nodes. */ +static GTY((param_is (struct varpool_node))) htab_t varpool_hash; + +/* The linked list of cgraph varpool nodes. + Linked via node->next pointer. */ +struct varpool_node *varpool_nodes; + +/* Queue of cgraph nodes scheduled to be lowered and output. + The queue is maintained via mark_needed_node, linked via node->next_needed + pointer. + + LAST_NEEDED_NODE points to the end of queue, so it can be + maintained in forward order. GTY is needed to make it friendly to + PCH. + + During compilation we construct the queue of needed variables + twice: first time it is during cgraph construction, second time it is at the + end of compilation in VARPOOL_REMOVE_UNREFERENCED_DECLS so we can avoid + optimized out variables being output. + + Each variable is thus first analyzed and then later possibly output. + FIRST_UNANALYZED_NODE points to first node in queue that was not analyzed + yet and is moved via VARPOOL_ANALYZE_PENDING_DECLS. */ + +struct varpool_node *varpool_nodes_queue; +static GTY(()) struct varpool_node *varpool_last_needed_node; +static GTY(()) struct varpool_node *varpool_first_unanalyzed_node; + +/* Lists all assembled variables to be sent to debugger output later on. */ +static GTY(()) struct varpool_node *varpool_assembled_nodes_queue; + +/* Return name of the node used in debug output. */ +const char * +varpool_node_name (struct varpool_node *node) +{ + return lang_hooks.decl_printable_name (node->decl, 2); +} + +/* Returns a hash code for P. */ +static hashval_t +hash_varpool_node (const void *p) +{ + const struct varpool_node *n = (const struct varpool_node *) p; + return (hashval_t) DECL_UID (n->decl); +} + +/* Returns nonzero if P1 and P2 are equal. */ +static int +eq_varpool_node (const void *p1, const void *p2) +{ + const struct varpool_node *n1 = + (const struct varpool_node *) p1; + const struct varpool_node *n2 = + (const struct varpool_node *) p2; + return DECL_UID (n1->decl) == DECL_UID (n2->decl); +} + +/* Return varpool node assigned to DECL without creating new one. */ +struct varpool_node * +varpool_get_node (const_tree decl) +{ + struct varpool_node key, **slot; + + gcc_assert (TREE_CODE (decl) == VAR_DECL + && (TREE_STATIC (decl) || DECL_EXTERNAL (decl))); + + if (!varpool_hash) + return NULL; + key.decl = CONST_CAST2 (tree, const_tree, decl); + slot = (struct varpool_node **) + htab_find_slot (varpool_hash, &key, NO_INSERT); + if (!slot) + return NULL; + return *slot; +} + +/* Return varpool node assigned to DECL. Create new one when needed. */ +struct varpool_node * +varpool_node (tree decl) +{ + struct varpool_node key, *node, **slot; + + gcc_assert (TREE_CODE (decl) == VAR_DECL + && (TREE_STATIC (decl) || DECL_EXTERNAL (decl))); + + if (!varpool_hash) + varpool_hash = htab_create_ggc (10, hash_varpool_node, + eq_varpool_node, NULL); + key.decl = decl; + slot = (struct varpool_node **) + htab_find_slot (varpool_hash, &key, INSERT); + if (*slot) + return *slot; + node = ggc_alloc_cleared_varpool_node (); + node->decl = decl; + node->order = cgraph_order++; + node->next = varpool_nodes; + ipa_empty_ref_list (&node->ref_list); + if (varpool_nodes) + varpool_nodes->prev = node; + varpool_nodes = node; + *slot = node; + return node; +} + +/* Remove node from the varpool. */ +void +varpool_remove_node (struct varpool_node *node) +{ + void **slot; + slot = htab_find_slot (varpool_hash, node, NO_INSERT); + gcc_assert (*slot == node); + htab_clear_slot (varpool_hash, slot); + gcc_assert (!varpool_assembled_nodes_queue); + if (!node->alias) + while (node->extra_name) + varpool_remove_node (node->extra_name); + if (node->next) + node->next->prev = node->prev; + if (node->prev) + node->prev->next = node->next; + else + { + if (node->alias && node->extra_name) + { + gcc_assert (node->extra_name->extra_name == node); + node->extra_name->extra_name = node->next; + } + else + { + gcc_assert (varpool_nodes == node); + varpool_nodes = node->next; + } + } + if (varpool_first_unanalyzed_node == node) + varpool_first_unanalyzed_node = node->next_needed; + if (node->next_needed) + node->next_needed->prev_needed = node->prev_needed; + else if (node->prev_needed) + { + gcc_assert (varpool_last_needed_node); + varpool_last_needed_node = node->prev_needed; + } + if (node->prev_needed) + node->prev_needed->next_needed = node->next_needed; + else if (node->next_needed) + { + gcc_assert (varpool_nodes_queue == node); + varpool_nodes_queue = node->next_needed; + } + if (node->same_comdat_group) + { + struct varpool_node *prev; + for (prev = node->same_comdat_group; + prev->same_comdat_group != node; + prev = prev->same_comdat_group) + ; + if (node->same_comdat_group == prev) + prev->same_comdat_group = NULL; + else + prev->same_comdat_group = node->same_comdat_group; + node->same_comdat_group = NULL; + } + ipa_remove_all_references (&node->ref_list); + ipa_remove_all_refering (&node->ref_list); + ggc_free (node); +} + +/* Dump given cgraph node. */ +void +dump_varpool_node (FILE *f, struct varpool_node *node) +{ + fprintf (f, "%s:", varpool_node_name (node)); + fprintf (f, " availability:%s", + cgraph_function_flags_ready + ? cgraph_availability_names[cgraph_variable_initializer_availability (node)] + : "not-ready"); + if (DECL_ASSEMBLER_NAME_SET_P (node->decl)) + fprintf (f, " (asm: %s)", IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl))); + if (DECL_INITIAL (node->decl)) + fprintf (f, " initialized"); + if (TREE_ASM_WRITTEN (node->decl)) + fprintf (f, " (asm written)"); + if (node->needed) + fprintf (f, " needed"); + if (node->analyzed) + fprintf (f, " analyzed"); + if (node->finalized) + fprintf (f, " finalized"); + if (node->output) + fprintf (f, " output"); + if (node->externally_visible) + fprintf (f, " externally_visible"); + if (node->resolution != LDPR_UNKNOWN) + fprintf (f, " %s", + ld_plugin_symbol_resolution_names[(int)node->resolution]); + if (node->in_other_partition) + fprintf (f, " in_other_partition"); + else if (node->used_from_other_partition) + fprintf (f, " used_from_other_partition"); + fprintf (f, "\n"); + fprintf (f, " References: "); + ipa_dump_references (f, &node->ref_list); + fprintf (f, " Refering this var: "); + ipa_dump_refering (f, &node->ref_list); +} + +/* Dump the variable pool. */ +void +dump_varpool (FILE *f) +{ + struct varpool_node *node; + + fprintf (f, "variable pool:\n\n"); + for (node = varpool_nodes; node; node = node->next) + dump_varpool_node (f, node); +} + +/* Dump the variable pool to stderr. */ + +DEBUG_FUNCTION void +debug_varpool (void) +{ + dump_varpool (stderr); +} + +/* Given an assembler name, lookup node. */ +struct varpool_node * +varpool_node_for_asm (tree asmname) +{ + struct varpool_node *node; + + for (node = varpool_nodes; node ; node = node->next) + if (decl_assembler_name_equal (node->decl, asmname)) + return node; + + return NULL; +} + +/* Helper function for finalization code - add node into lists so it will + be analyzed and compiled. */ +static void +varpool_enqueue_needed_node (struct varpool_node *node) +{ + if (varpool_last_needed_node) + { + varpool_last_needed_node->next_needed = node; + node->prev_needed = varpool_last_needed_node; + } + varpool_last_needed_node = node; + node->next_needed = NULL; + if (!varpool_nodes_queue) + varpool_nodes_queue = node; + if (!varpool_first_unanalyzed_node) + varpool_first_unanalyzed_node = node; + notice_global_symbol (node->decl); +} + +/* Notify finalize_compilation_unit that given node is reachable + or needed. */ +void +varpool_mark_needed_node (struct varpool_node *node) +{ + if (node->alias && node->extra_name) + node = node->extra_name; + if (!node->needed && node->finalized + && !TREE_ASM_WRITTEN (node->decl)) + varpool_enqueue_needed_node (node); + node->needed = 1; +} + +/* Reset the queue of needed nodes. */ +void +varpool_reset_queue (void) +{ + varpool_last_needed_node = NULL; + varpool_nodes_queue = NULL; + varpool_first_unanalyzed_node = NULL; +} + +/* Determine if variable DECL is needed. That is, visible to something + either outside this translation unit, something magic in the system + configury */ +bool +decide_is_variable_needed (struct varpool_node *node, tree decl) +{ + /* If the user told us it is used, then it must be so. */ + if (node->force_output) + return true; + + gcc_assert (!DECL_EXTERNAL (decl)); + + /* Externally visible variables must be output. The exception is + COMDAT variables that must be output only when they are needed. */ + if (TREE_PUBLIC (decl) + && !DECL_COMDAT (decl) + && !DECL_EXTERNAL (decl)) + return true; + + /* When not reordering top level variables, we have to assume that + we are going to keep everything. */ + if (!flag_toplevel_reorder) + return true; + return false; +} + +/* Return if DECL is constant and its initial value is known (so we can do + constant folding using DECL_INITIAL (decl)). */ + +bool +const_value_known_p (tree decl) +{ + if (TREE_CODE (decl) != VAR_DECL + &&TREE_CODE (decl) != CONST_DECL) + return false; + + if (TREE_CODE (decl) == CONST_DECL + || DECL_IN_CONSTANT_POOL (decl)) + return true; + + gcc_assert (TREE_CODE (decl) == VAR_DECL); + + if (!TREE_READONLY (decl) || TREE_THIS_VOLATILE (decl)) + return false; + + /* Gimplifier takes away constructors of local vars */ + if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl)) + return DECL_INITIAL (decl) != NULL; + + gcc_assert (TREE_STATIC (decl) || DECL_EXTERNAL (decl)); + + /* Variables declared 'const' without an initializer + have zero as the initializer if they may not be + overridden at link or run time. */ + if (!DECL_INITIAL (decl) + && (DECL_EXTERNAL (decl) + || decl_replaceable_p (decl))) + return false; + + /* Variables declared `const' with an initializer are considered + to not be overwritable with different initializer by default. + + ??? Previously we behaved so for scalar variables but not for array + accesses. */ + return true; +} + +/* Mark DECL as finalized. By finalizing the declaration, frontend instruct the + middle end to output the variable to asm file, if needed or externally + visible. */ +void +varpool_finalize_decl (tree decl) +{ + struct varpool_node *node = varpool_node (decl); + + gcc_assert (TREE_STATIC (decl)); + + /* The first declaration of a variable that comes through this function + decides whether it is global (in C, has external linkage) + or local (in C, has internal linkage). So do nothing more + if this function has already run. */ + if (node->finalized) + { + if (cgraph_global_info_ready) + varpool_assemble_pending_decls (); + return; + } + if (node->needed) + varpool_enqueue_needed_node (node); + node->finalized = true; + if (TREE_THIS_VOLATILE (decl) || DECL_PRESERVE_P (decl)) + node->force_output = true; + + if (decide_is_variable_needed (node, decl)) + varpool_mark_needed_node (node); + if (cgraph_global_info_ready) + varpool_assemble_pending_decls (); +} + +/* Return variable availability. See cgraph.h for description of individual + return values. */ +enum availability +cgraph_variable_initializer_availability (struct varpool_node *node) +{ + gcc_assert (cgraph_function_flags_ready); + if (!node->finalized) + return AVAIL_NOT_AVAILABLE; + if (!TREE_PUBLIC (node->decl)) + return AVAIL_AVAILABLE; + /* If the variable can be overwritten, return OVERWRITABLE. Takes + care of at least two notable extensions - the COMDAT variables + used to share template instantiations in C++. */ + if (!decl_replaceable_p (node->decl)) + return AVAIL_OVERWRITABLE; + return AVAIL_AVAILABLE; +} + +/* Walk the decls we marked as necessary and see if they reference new + variables or functions and add them into the worklists. */ +bool +varpool_analyze_pending_decls (void) +{ + bool changed = false; + + timevar_push (TV_VARPOOL); + while (varpool_first_unanalyzed_node) + { + struct varpool_node *node = varpool_first_unanalyzed_node, *next; + tree decl = node->decl; + bool analyzed = node->analyzed; + + varpool_first_unanalyzed_node->analyzed = true; + + varpool_first_unanalyzed_node = varpool_first_unanalyzed_node->next_needed; + + /* When reading back varpool at LTO time, we re-construct the queue in order + to have "needed" list right by inserting all needed nodes into varpool. + We however don't want to re-analyze already analyzed nodes. */ + if (!analyzed) + { + gcc_assert (!in_lto_p || cgraph_function_flags_ready); + /* Compute the alignment early so function body expanders are + already informed about increased alignment. */ + align_variable (decl, 0); + } + if (DECL_INITIAL (decl)) + record_references_in_initializer (decl, analyzed); + if (node->same_comdat_group) + { + for (next = node->same_comdat_group; + next != node; + next = next->same_comdat_group) + varpool_mark_needed_node (next); + } + changed = true; + } + timevar_pop (TV_VARPOOL); + return changed; +} + +/* Output one variable, if necessary. Return whether we output it. */ +bool +varpool_assemble_decl (struct varpool_node *node) +{ + tree decl = node->decl; + + if (!TREE_ASM_WRITTEN (decl) + && !node->alias + && !node->in_other_partition + && !DECL_EXTERNAL (decl) + && (TREE_CODE (decl) != VAR_DECL || !DECL_HAS_VALUE_EXPR_P (decl))) + { + assemble_variable (decl, 0, 1, 0); + if (TREE_ASM_WRITTEN (decl)) + { + struct varpool_node *alias; + + node->next_needed = varpool_assembled_nodes_queue; + node->prev_needed = NULL; + if (varpool_assembled_nodes_queue) + varpool_assembled_nodes_queue->prev_needed = node; + varpool_assembled_nodes_queue = node; + node->finalized = 1; + + /* Also emit any extra name aliases. */ + for (alias = node->extra_name; alias; alias = alias->next) + { + /* Update linkage fields in case they've changed. */ + DECL_WEAK (alias->decl) = DECL_WEAK (decl); + TREE_PUBLIC (alias->decl) = TREE_PUBLIC (decl); + DECL_VISIBILITY (alias->decl) = DECL_VISIBILITY (decl); + assemble_alias (alias->decl, DECL_ASSEMBLER_NAME (decl)); + } + + return true; + } + } + + return false; +} + +/* Optimization of function bodies might've rendered some variables as + unnecessary so we want to avoid these from being compiled. + + This is done by pruning the queue and keeping only the variables that + really appear needed (ie they are either externally visible or referenced + by compiled function). Re-doing the reachability analysis on variables + brings back the remaining variables referenced by these. */ +void +varpool_remove_unreferenced_decls (void) +{ + struct varpool_node *next, *node = varpool_nodes_queue; + + varpool_reset_queue (); + + if (seen_error ()) + return; + + while (node) + { + next = node->next_needed; + node->needed = 0; + + if (node->analyzed + && (!varpool_can_remove_if_no_refs (node) + /* We just expanded all function bodies. See if any of + them needed the variable. */ + || DECL_RTL_SET_P (node->decl))) + varpool_mark_needed_node (node); + + node = next; + } + /* Make sure we mark alias targets as used targets. */ + finish_aliases_1 (); + varpool_analyze_pending_decls (); +} + +/* For variables in named sections make sure get_variable_section + is called before we switch to those sections. Then section + conflicts between read-only and read-only requiring relocations + sections can be resolved. */ +void +varpool_finalize_named_section_flags (struct varpool_node *node) +{ + if (!TREE_ASM_WRITTEN (node->decl) + && !node->alias + && !node->in_other_partition + && !DECL_EXTERNAL (node->decl) + && TREE_CODE (node->decl) == VAR_DECL + && !DECL_HAS_VALUE_EXPR_P (node->decl) + && DECL_SECTION_NAME (node->decl)) + get_variable_section (node->decl, false); +} + +/* Output all variables enqueued to be assembled. */ +bool +varpool_assemble_pending_decls (void) +{ + bool changed = false; + struct varpool_node *node; + + if (seen_error ()) + return false; + + timevar_push (TV_VAROUT); + /* EH might mark decls as needed during expansion. This should be safe since + we don't create references to new function, but it should not be used + elsewhere. */ + varpool_analyze_pending_decls (); + + for (node = varpool_nodes_queue; node; node = node->next_needed) + varpool_finalize_named_section_flags (node); + + while (varpool_nodes_queue) + { + struct varpool_node *node = varpool_nodes_queue; + + varpool_nodes_queue = varpool_nodes_queue->next_needed; + if (varpool_assemble_decl (node)) + changed = true; + else + { + node->prev_needed = NULL; + node->next_needed = NULL; + } + } + /* varpool_nodes_queue is now empty, clear the pointer to the last element + in the queue. */ + varpool_last_needed_node = NULL; + timevar_pop (TV_VAROUT); + return changed; +} + +/* Remove all elements from the queue so we can re-use it for debug output. */ +void +varpool_empty_needed_queue (void) +{ + /* EH might mark decls as needed during expansion. This should be safe since + we don't create references to new function, but it should not be used + elsewhere. */ + varpool_analyze_pending_decls (); + + while (varpool_nodes_queue) + { + struct varpool_node *node = varpool_nodes_queue; + varpool_nodes_queue = varpool_nodes_queue->next_needed; + node->next_needed = NULL; + node->prev_needed = NULL; + } + /* varpool_nodes_queue is now empty, clear the pointer to the last element + in the queue. */ + varpool_last_needed_node = NULL; +} + +/* Create a new global variable of type TYPE. */ +tree +add_new_static_var (tree type) +{ + tree new_decl; + struct varpool_node *new_node; + + new_decl = create_tmp_var (type, NULL); + DECL_NAME (new_decl) = create_tmp_var_name (NULL); + TREE_READONLY (new_decl) = 0; + TREE_STATIC (new_decl) = 1; + TREE_USED (new_decl) = 1; + DECL_CONTEXT (new_decl) = NULL_TREE; + DECL_ABSTRACT (new_decl) = 0; + lang_hooks.dup_lang_specific_decl (new_decl); + create_var_ann (new_decl); + new_node = varpool_node (new_decl); + varpool_mark_needed_node (new_node); + add_referenced_var (new_decl); + varpool_finalize_decl (new_decl); + + return new_node->decl; +} + +/* Attempt to mark ALIAS as an alias to DECL. Return TRUE if successful. + Extra name aliases are output whenever DECL is output. */ + +struct varpool_node * +varpool_extra_name_alias (tree alias, tree decl) +{ + struct varpool_node key, *alias_node, *decl_node, **slot; + +#ifndef ASM_OUTPUT_DEF + /* If aliases aren't supported by the assembler, fail. */ + return false; +#endif + + gcc_assert (TREE_CODE (decl) == VAR_DECL); + gcc_assert (TREE_CODE (alias) == VAR_DECL); + /* Make sure the hash table has been created. */ + decl_node = varpool_node (decl); + + key.decl = alias; + + slot = (struct varpool_node **) htab_find_slot (varpool_hash, &key, INSERT); + + /* If the varpool_node has been already created, fail. */ + if (*slot) + return NULL; + + alias_node = ggc_alloc_cleared_varpool_node (); + alias_node->decl = alias; + alias_node->alias = 1; + alias_node->extra_name = decl_node; + alias_node->next = decl_node->extra_name; + ipa_empty_ref_list (&alias_node->ref_list); + if (decl_node->extra_name) + decl_node->extra_name->prev = alias_node; + decl_node->extra_name = alias_node; + *slot = alias_node; + return alias_node; +} + +/* Return true when NODE is known to be used from other (non-LTO) object file. + Known only when doing LTO via linker plugin. */ + +bool +varpool_used_from_object_file_p (struct varpool_node *node) +{ + struct varpool_node *alias; + + if (!TREE_PUBLIC (node->decl)) + return false; + if (resolution_used_from_other_file_p (node->resolution)) + return true; + for (alias = node->extra_name; alias; alias = alias->next) + if (TREE_PUBLIC (alias->decl) + && resolution_used_from_other_file_p (alias->resolution)) + return true; + return false; +} + +#include "gt-varpool.h" -- cgit v1.2.3