/* Callgraph handling code.
- Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2010, 2011
+ Free Software Foundation, Inc.
Contributed by Jan Hubicka
This file is part of GCC.
#include "tree.h"
#include "cgraph.h"
#include "langhooks.h"
-#include "diagnostic.h"
+#include "diagnostic-core.h"
#include "hashtab.h"
#include "ggc.h"
#include "timevar.h"
-#include "debug.h"
+#include "debug.h"
#include "target.h"
#include "output.h"
-#include "tree-gimple.h"
+#include "gimple.h"
#include "tree-flow.h"
+#include "flags.h"
/* This file contains basic routines manipulating variable pool.
/* Queue of cgraph nodes scheduled to be lowered and output.
The queue is maintained via mark_needed_node, linked via node->next_needed
- pointer.
+ 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.
+
+ 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;
static GTY(()) struct varpool_node *varpool_assembled_nodes_queue;
/* Return name of the node used in debug output. */
-static const char *
+const char *
varpool_node_name (struct varpool_node *node)
{
return lang_hooks.decl_printable_name (node->decl, 2);
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 (DECL_P (decl) && TREE_CODE (decl) != FUNCTION_DECL);
+ 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,
htab_find_slot (varpool_hash, &key, INSERT);
if (*slot)
return *slot;
- node = GGC_CNEW (struct varpool_node);
+ 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)
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, " 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. */
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)
varpool_enqueue_needed_node (struct varpool_node *node)
{
if (varpool_last_needed_node)
- varpool_last_needed_node->next_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)
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);
}
/* Reset the queue of needed nodes. */
-static void
+void
varpool_reset_queue (void)
{
varpool_last_needed_node = NULL;
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->externally_visible || node->force_output)
+ if (node->force_output)
return true;
- /* ??? If the assembler name is set by hand, it is possible to assemble
- the name later after finalizing the function and the fact is noticed
- in assemble_name then. This is arguably a bug. */
- if (DECL_ASSEMBLER_NAME_SET_P (decl)
- && TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl)))
- return true;
-
- /* If we decided it was needed before, but at the time we didn't have
- the definition available, then it's still needed. */
- if (node->needed)
- 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) && !flag_whole_program && !DECL_COMDAT (decl)
+ if (TREE_PUBLIC (decl)
+ && !DECL_COMDAT (decl)
&& !DECL_EXTERNAL (decl))
return true;
- /* When emulating tls, we actually see references to the control
- variable, rather than the user-level variable. */
- if (!targetm.have_tls
- && TREE_CODE (decl) == VAR_DECL
- && DECL_THREAD_LOCAL_P (decl))
- {
- tree control = emutls_decl (decl);
- if (decide_is_variable_needed (varpool_node (control), control))
- return true;
- }
-
/* When not reordering top level variables, we have to assume that
we are going to keep everything. */
- if (flag_toplevel_reorder)
+ 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;
- /* We want to emit COMDAT variables only when absolutely necessary. */
- if (DECL_COMDAT (decl))
+ /* 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;
}
{
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 (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);
- /* Since we reclaim unreachable nodes at the end of every language
- level unit, we need to be conservative about possible entry points
- there. */
- else if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl) && !DECL_EXTERNAL (decl))
- varpool_mark_needed_node (node);
if (cgraph_global_info_ready)
varpool_assemble_pending_decls ();
}
/* 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 (!(*targetm.binds_local_p) (node->decl) && !DECL_COMDAT (node->decl))
+ if (!decl_replaceable_p (node->decl))
return AVAIL_OVERWRITABLE;
return AVAIL_AVAILABLE;
}
varpool_analyze_pending_decls (void)
{
bool changed = false;
- timevar_push (TV_CGRAPH);
+ timevar_push (TV_VARPOOL);
while (varpool_first_unanalyzed_node)
{
- tree decl = varpool_first_unanalyzed_node->decl;
+ 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;
- /* Compute the alignment early so function body expanders are
- already informed about increased alignment. */
- align_variable (decl, 0);
-
+ /* 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);
+ 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_CGRAPH);
+ timevar_pop (TV_VARPOOL);
return changed;
}
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;
}
}
varpool_reset_queue ();
- if (errorcount || sorrycount)
+ if (seen_error ())
return;
while (node)
{
- tree decl = node->decl;
next = node->next_needed;
node->needed = 0;
- if (node->finalized
- && (decide_is_variable_needed (node, decl)
- /* ??? Cgraph does not yet rule the world with an iron hand,
- and does not control the emission of debug information.
- After a variable has its DECL_RTL set, we must assume that
- it may be referenced by the debug information, and we can
- no longer elide it. */
- || DECL_RTL_SET_P (decl)))
+ 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;
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 (errorcount || sorrycount)
+ 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;
if (varpool_assemble_decl (node))
changed = true;
else
- node->next_needed = NULL;
+ {
+ 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;
}
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;
}
-/* Output all variables enqueued to be assembled. */
-void
-varpool_output_debug_info (void)
-{
- timevar_push (TV_SYMOUT);
- if (errorcount == 0 && sorrycount == 0)
- while (varpool_assembled_nodes_queue)
- {
- struct varpool_node *node = varpool_assembled_nodes_queue;
-
- /* Local static variables are never seen by check_global_declarations
- so we need to output debug info by hand. */
- if (DECL_CONTEXT (node->decl)
- && (TREE_CODE (DECL_CONTEXT (node->decl)) == BLOCK
- || TREE_CODE (DECL_CONTEXT (node->decl)) == FUNCTION_DECL)
- && errorcount == 0 && sorrycount == 0)
- (*debug_hooks->global_decl) (node->decl);
- varpool_assembled_nodes_queue = node->next_needed;
- node->next_needed = 0;
- }
- timevar_pop (TV_SYMOUT);
-}
-
/* Create a new global variable of type TYPE. */
tree
add_new_static_var (tree type)
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"
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