forked from illumos/gcc
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cgraphunit.c
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/
cgraphunit.c
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/* Callgraph based intraprocedural optimizations.
Copyright (C) 2003, 2004, 2005 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 2, 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 COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/* This module implements main driver of compilation process as well as
few basic intraprocedural optimizers.
The main scope of this file is to act as an interface in between
tree based frontends and the backend (and middle end)
The front-end is supposed to use following functionality:
- cgraph_finalize_function
This function is called once front-end has parsed whole body of function
and it is certain that the function body nor the declaration will change.
(There is one exception needed for implementing GCC extern inline function.)
- cgraph_varpool_finalize_variable
This function has same behavior as the above but is used for static
variables.
- cgraph_finalize_compilation_unit
This function is called once compilation unit is finalized and it will
no longer change.
In the unit-at-a-time the call-graph construction and local function
analysis takes place here. Bodies of unreachable functions are released
to conserve memory usage.
??? The compilation unit in this point of view should be compilation
unit as defined by the language - for instance C frontend allows multiple
compilation units to be parsed at once and it should call function each
time parsing is done so we save memory.
- cgraph_optimize
In this unit-at-a-time compilation the intra procedural analysis takes
place here. In particular the static functions whose address is never
taken are marked as local. Backend can then use this information to
modify calling conventions, do better inlining or similar optimizations.
- cgraph_assemble_pending_functions
- cgraph_varpool_assemble_pending_variables
In non-unit-at-a-time mode these functions can be used to force compilation
of functions or variables that are known to be needed at given stage
of compilation
- cgraph_mark_needed_node
- cgraph_varpool_mark_needed_node
When function or variable is referenced by some hidden way (for instance
via assembly code and marked by attribute "used"), the call-graph data structure
must be updated accordingly by this function.
- analyze_expr callback
This function is responsible for lowering tree nodes not understood by
generic code into understandable ones or alternatively marking
callgraph and varpool nodes referenced by the as needed.
??? On the tree-ssa genericizing should take place here and we will avoid
need for these hooks (replacing them by genericizing hook)
- expand_function callback
This function is used to expand function and pass it into RTL back-end.
Front-end should not make any assumptions about when this function can be
called. In particular cgraph_assemble_pending_functions,
cgraph_varpool_assemble_pending_variables, cgraph_finalize_function,
cgraph_varpool_finalize_function, cgraph_optimize can cause arbitrarily
previously finalized functions to be expanded.
We implement two compilation modes.
- unit-at-a-time: In this mode analyzing of all functions is deferred
to cgraph_finalize_compilation_unit and expansion into cgraph_optimize.
In cgraph_finalize_compilation_unit the reachable functions are
analyzed. During analysis the call-graph edges from reachable
functions are constructed and their destinations are marked as
reachable. References to functions and variables are discovered too
and variables found to be needed output to the assembly file. Via
mark_referenced call in assemble_variable functions referenced by
static variables are noticed too.
The intra-procedural information is produced and its existence
indicated by global_info_ready. Once this flag is set it is impossible
to change function from !reachable to reachable and thus
assemble_variable no longer call mark_referenced.
Finally the call-graph is topologically sorted and all reachable functions
that has not been completely inlined or are not external are output.
??? It is possible that reference to function or variable is optimized
out. We can not deal with this nicely because topological order is not
suitable for it. For tree-ssa we may consider another pass doing
optimization and re-discovering reachable functions.
??? Reorganize code so variables are output very last and only if they
really has been referenced by produced code, so we catch more cases
where reference has been optimized out.
- non-unit-at-a-time
All functions are variables are output as early as possible to conserve
memory consumption. This may or may not result in less memory used but
it is still needed for some legacy code that rely on particular ordering
of things output from the compiler.
Varpool data structures are not used and variables are output directly.
Functions are output early using call of
cgraph_assemble_pending_function from cgraph_finalize_function. The
decision on whether function is needed is made more conservative so
uninlininable static functions are needed too. During the call-graph
construction the edge destinations are not marked as reachable and it
is completely relied upn assemble_variable to mark them.
Inlining decision heuristics
??? Move this to separate file after tree-ssa merge.
We separate inlining decisions from the inliner itself and store it
inside callgraph as so called inline plan. Refer to cgraph.c
documentation about particular representation of inline plans in the
callgraph
The implementation of particular heuristics is separated from
the rest of code to make it easier to replace it with more complicated
implementation in the future. The rest of inlining code acts as a
library aimed to modify the callgraph and verify that the parameters
on code size growth fits.
To mark given call inline, use cgraph_mark_inline function, the
verification is performed by cgraph_default_inline_p and
cgraph_check_inline_limits.
The heuristics implements simple knapsack style algorithm ordering
all functions by their "profitability" (estimated by code size growth)
and inlining them in priority order.
cgraph_decide_inlining implements heuristics taking whole callgraph
into account, while cgraph_decide_inlining_incrementally considers
only one function at a time and is used in non-unit-at-a-time mode. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "tree-flow.h"
#include "tree-inline.h"
#include "langhooks.h"
#include "pointer-set.h"
#include "toplev.h"
#include "flags.h"
#include "ggc.h"
#include "debug.h"
#include "target.h"
#include "cgraph.h"
#include "diagnostic.h"
#include "timevar.h"
#include "params.h"
#include "fibheap.h"
#include "c-common.h"
#include "intl.h"
#include "function.h"
#include "tree-gimple.h"
#define INSNS_PER_CALL 10
static void cgraph_expand_all_functions (void);
static void cgraph_mark_functions_to_output (void);
static void cgraph_expand_function (struct cgraph_node *);
static tree record_call_1 (tree *, int *, void *);
static void cgraph_mark_local_functions (void);
static bool cgraph_default_inline_p (struct cgraph_node *n);
static void cgraph_analyze_function (struct cgraph_node *node);
static void cgraph_decide_inlining_incrementally (struct cgraph_node *);
/* Statistics we collect about inlining algorithm. */
static int ncalls_inlined;
static int nfunctions_inlined;
static int initial_insns;
static int overall_insns;
/* Records tree nodes seen in cgraph_create_edges. Simply using
walk_tree_without_duplicates doesn't guarantee each node is visited
once because it gets a new htab upon each recursive call from
record_calls_1. */
static struct pointer_set_t *visited_nodes;
static FILE *cgraph_dump_file;
/* Determine if function DECL is needed. That is, visible to something
either outside this translation unit, something magic in the system
configury, or (if not doing unit-at-a-time) to something we havn't
seen yet. */
static bool
decide_is_function_needed (struct cgraph_node *node, tree decl)
{
tree origin;
/* If we decided it was needed before, but at the time we didn't have
the body of the function available, then it's still needed. We have
to go back and re-check its dependencies now. */
if (node->needed)
return true;
/* Externally visible functions must be output. The exception is
COMDAT functions that must be output only when they are needed. */
if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl) && !DECL_EXTERNAL (decl))
return true;
/* Constructors and destructors are reachable from the runtime by
some mechanism. */
if (DECL_STATIC_CONSTRUCTOR (decl) || DECL_STATIC_DESTRUCTOR (decl))
return true;
/* If the user told us it is used, then it must be so. */
if (lookup_attribute ("used", DECL_ATTRIBUTES (decl)))
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 (flag_unit_at_a_time)
return false;
/* If not doing unit at a time, then we'll only defer this function
if its marked for inlining. Otherwise we want to emit it now. */
/* "extern inline" functions are never output locally. */
if (DECL_EXTERNAL (decl))
return false;
/* Nested functions of extern inline function shall not be emit unless
we inlined the origin. */
for (origin = decl_function_context (decl); origin;
origin = decl_function_context (origin))
if (DECL_EXTERNAL (origin))
return false;
/* We want to emit COMDAT functions only when absolutely necessary. */
if (DECL_COMDAT (decl))
return false;
if (!DECL_INLINE (decl)
|| (!node->local.disregard_inline_limits
/* When declared inline, defer even the uninlinable functions.
This allows them to be eliminated when unused. */
&& !DECL_DECLARED_INLINE_P (decl)
&& (!node->local.inlinable || !cgraph_default_inline_p (node))))
return true;
return false;
}
/* When not doing unit-at-a-time, output all functions enqueued.
Return true when such a functions were found. */
bool
cgraph_assemble_pending_functions (void)
{
bool output = false;
if (flag_unit_at_a_time)
return false;
while (cgraph_nodes_queue)
{
struct cgraph_node *n = cgraph_nodes_queue;
cgraph_nodes_queue = cgraph_nodes_queue->next_needed;
n->next_needed = NULL;
if (!n->global.inlined_to
&& !n->alias
&& !DECL_EXTERNAL (n->decl))
{
cgraph_expand_function (n);
output = true;
}
}
return output;
}
/* DECL has been parsed. Take it, queue it, compile it at the whim of the
logic in effect. If NESTED is true, then our caller cannot stand to have
the garbage collector run at the moment. We would need to either create
a new GC context, or just not compile right now. */
void
cgraph_finalize_function (tree decl, bool nested)
{
struct cgraph_node *node = cgraph_node (decl);
if (node->local.finalized)
{
/* As an GCC extension we allow redefinition of the function. The
semantics when both copies of bodies differ is not well defined.
We replace the old body with new body so in unit at a time mode
we always use new body, while in normal mode we may end up with
old body inlined into some functions and new body expanded and
inlined in others.
??? It may make more sense to use one body for inlining and other
body for expanding the function but this is difficult to do. */
/* If node->output is set, then this is a unit-at-a-time compilation
and we have already begun whole-unit analysis. This is *not*
testing for whether we've already emitted the function. That
case can be sort-of legitimately seen with real function
redefinition errors. I would argue that the front end should
never present us with such a case, but don't enforce that for now. */
gcc_assert (!node->output);
/* Reset our data structures so we can analyze the function again. */
memset (&node->local, 0, sizeof (node->local));
memset (&node->global, 0, sizeof (node->global));
memset (&node->rtl, 0, sizeof (node->rtl));
node->analyzed = false;
node->local.redefined_extern_inline = true;
if (!flag_unit_at_a_time)
{
struct cgraph_node *n;
for (n = cgraph_nodes; n; n = n->next)
if (n->global.inlined_to == node)
cgraph_remove_node (n);
}
cgraph_node_remove_callees (node);
/* We may need to re-queue the node for assembling in case
we already proceeded it and ignored as not needed. */
if (node->reachable && !flag_unit_at_a_time)
{
struct cgraph_node *n;
for (n = cgraph_nodes_queue; n; n = n->next_needed)
if (n == node)
break;
if (!n)
node->reachable = 0;
}
}
notice_global_symbol (decl);
node->decl = decl;
node->local.finalized = true;
if (node->nested)
lower_nested_functions (decl);
gcc_assert (!node->nested);
/* If not unit at a time, then we need to create the call graph
now, so that called functions can be queued and emitted now. */
if (!flag_unit_at_a_time)
{
cgraph_analyze_function (node);
cgraph_decide_inlining_incrementally (node);
}
if (decide_is_function_needed (node, decl))
cgraph_mark_needed_node (node);
/* If not unit at a time, go ahead and emit everything we've found
to be reachable at this time. */
if (!nested)
{
if (!cgraph_assemble_pending_functions ())
ggc_collect ();
}
/* If we've not yet emitted decl, tell the debug info about it. */
if (!TREE_ASM_WRITTEN (decl))
(*debug_hooks->deferred_inline_function) (decl);
/* Possibly warn about unused parameters. */
if (warn_unused_parameter)
do_warn_unused_parameter (decl);
}
/* Walk tree and record all calls. Called via walk_tree. */
static tree
record_call_1 (tree *tp, int *walk_subtrees, void *data)
{
tree t = *tp;
switch (TREE_CODE (t))
{
case VAR_DECL:
/* ??? Really, we should mark this decl as *potentially* referenced
by this function and re-examine whether the decl is actually used
after rtl has been generated. */
if (TREE_STATIC (t))
{
cgraph_varpool_mark_needed_node (cgraph_varpool_node (t));
if (lang_hooks.callgraph.analyze_expr)
return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees,
data);
}
break;
case ADDR_EXPR:
if (flag_unit_at_a_time)
{
/* Record dereferences to the functions. This makes the
functions reachable unconditionally. */
tree decl = TREE_OPERAND (*tp, 0);
if (TREE_CODE (decl) == FUNCTION_DECL)
cgraph_mark_needed_node (cgraph_node (decl));
}
break;
case CALL_EXPR:
{
tree decl = get_callee_fndecl (*tp);
if (decl && TREE_CODE (decl) == FUNCTION_DECL)
{
cgraph_create_edge (data, cgraph_node (decl), *tp);
/* When we see a function call, we don't want to look at the
function reference in the ADDR_EXPR that is hanging from
the CALL_EXPR we're examining here, because we would
conclude incorrectly that the function's address could be
taken by something that is not a function call. So only
walk the function parameter list, skip the other subtrees. */
walk_tree (&TREE_OPERAND (*tp, 1), record_call_1, data,
visited_nodes);
*walk_subtrees = 0;
}
break;
}
default:
/* Save some cycles by not walking types and declaration as we
won't find anything useful there anyway. */
if (IS_TYPE_OR_DECL_P (*tp))
{
*walk_subtrees = 0;
break;
}
if ((unsigned int) TREE_CODE (t) >= LAST_AND_UNUSED_TREE_CODE)
return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees, data);
break;
}
return NULL;
}
/* Create cgraph edges for function calls inside BODY from NODE. */
void
cgraph_create_edges (struct cgraph_node *node, tree body)
{
/* The nodes we're interested in are never shared, so walk
the tree ignoring duplicates. */
visited_nodes = pointer_set_create ();
walk_tree (&body, record_call_1, node, visited_nodes);
pointer_set_destroy (visited_nodes);
visited_nodes = NULL;
}
static bool error_found;
/* Callback of verify_cgraph_node. Check that all call_exprs have
cgraph nodes. */
static tree
verify_cgraph_node_1 (tree *tp, int *walk_subtrees, void *data)
{
tree t = *tp;
tree decl;
if (TREE_CODE (t) == CALL_EXPR && (decl = get_callee_fndecl (t)))
{
struct cgraph_edge *e = cgraph_edge (data, t);
if (e)
{
if (e->aux)
{
error ("Shared call_expr:");
debug_tree (t);
error_found = true;
}
if (e->callee->decl != cgraph_node (decl)->decl)
{
error ("Edge points to wrong declaration:");
debug_tree (e->callee->decl);
fprintf (stderr," Instead of:");
debug_tree (decl);
}
e->aux = (void *)1;
}
else
{
error ("Missing callgraph edge for call expr:");
debug_tree (t);
error_found = true;
}
}
/* Save some cycles by not walking types and declaration as we
won't find anything useful there anyway. */
if (IS_TYPE_OR_DECL_P (*tp))
*walk_subtrees = 0;
return NULL_TREE;
}
/* Verify cgraph nodes of given cgraph node. */
void
verify_cgraph_node (struct cgraph_node *node)
{
struct cgraph_edge *e;
struct cgraph_node *main_clone;
timevar_push (TV_CGRAPH_VERIFY);
error_found = false;
for (e = node->callees; e; e = e->next_callee)
if (e->aux)
{
error ("Aux field set for edge %s->%s",
cgraph_node_name (e->caller), cgraph_node_name (e->callee));
error_found = true;
}
for (e = node->callers; e; e = e->next_caller)
{
if (!e->inline_failed)
{
if (node->global.inlined_to
!= (e->caller->global.inlined_to
? e->caller->global.inlined_to : e->caller))
{
error ("Inlined_to pointer is wrong");
error_found = true;
}
if (node->callers->next_caller)
{
error ("Multiple inline callers");
error_found = true;
}
}
else
if (node->global.inlined_to)
{
error ("Inlined_to pointer set for noninline callers");
error_found = true;
}
}
if (!node->callers && node->global.inlined_to)
{
error ("Inlined_to pointer is set but no predecesors found");
error_found = true;
}
if (node->global.inlined_to == node)
{
error ("Inlined_to pointer reffers to itself");
error_found = true;
}
for (main_clone = cgraph_node (node->decl); main_clone;
main_clone = main_clone->next_clone)
if (main_clone == node)
break;
if (!node)
{
error ("Node not found in DECL_ASSEMBLER_NAME hash");
error_found = true;
}
if (node->analyzed
&& DECL_SAVED_TREE (node->decl) && !TREE_ASM_WRITTEN (node->decl)
&& (!DECL_EXTERNAL (node->decl) || node->global.inlined_to))
{
walk_tree_without_duplicates (&DECL_SAVED_TREE (node->decl),
verify_cgraph_node_1, node);
for (e = node->callees; e; e = e->next_callee)
{
if (!e->aux)
{
error ("Edge %s->%s has no corresponding call_expr",
cgraph_node_name (e->caller),
cgraph_node_name (e->callee));
error_found = true;
}
e->aux = 0;
}
}
if (error_found)
{
dump_cgraph_node (stderr, node);
internal_error ("verify_cgraph_node failed.");
}
timevar_pop (TV_CGRAPH_VERIFY);
}
/* Verify whole cgraph structure. */
void
verify_cgraph (void)
{
struct cgraph_node *node;
if (sorrycount || errorcount)
return;
for (node = cgraph_nodes; node; node = node->next)
verify_cgraph_node (node);
}
/* Analyze the function scheduled to be output. */
static void
cgraph_analyze_function (struct cgraph_node *node)
{
tree decl = node->decl;
struct cgraph_edge *e;
current_function_decl = decl;
/* First kill forward declaration so reverse inlining works properly. */
cgraph_create_edges (node, DECL_SAVED_TREE (decl));
node->local.inlinable = tree_inlinable_function_p (decl);
node->local.self_insns = estimate_num_insns (DECL_SAVED_TREE (decl));
if (node->local.inlinable)
node->local.disregard_inline_limits
= lang_hooks.tree_inlining.disregard_inline_limits (decl);
for (e = node->callers; e; e = e->next_caller)
{
if (node->local.redefined_extern_inline)
e->inline_failed = N_("redefined extern inline functions are not "
"considered for inlining");
else if (!node->local.inlinable)
e->inline_failed = N_("function not inlinable");
else
e->inline_failed = N_("function not considered for inlining");
}
if (flag_really_no_inline && !node->local.disregard_inline_limits)
node->local.inlinable = 0;
/* Inlining characteristics are maintained by the cgraph_mark_inline. */
node->global.insns = node->local.self_insns;
node->analyzed = true;
current_function_decl = NULL;
}
/* Analyze the whole compilation unit once it is parsed completely. */
void
cgraph_finalize_compilation_unit (void)
{
struct cgraph_node *node;
finish_aliases_1 ();
if (!flag_unit_at_a_time)
{
cgraph_assemble_pending_functions ();
return;
}
cgraph_varpool_assemble_pending_decls ();
if (!quiet_flag)
fprintf (stderr, "\nAnalyzing compilation unit\n");
timevar_push (TV_CGRAPH);
if (cgraph_dump_file)
{
fprintf (cgraph_dump_file, "Initial entry points:");
for (node = cgraph_nodes; node; node = node->next)
if (node->needed && DECL_SAVED_TREE (node->decl))
fprintf (cgraph_dump_file, " %s", cgraph_node_name (node));
fprintf (cgraph_dump_file, "\n");
}
/* Propagate reachability flag and lower representation of all reachable
functions. In the future, lowering will introduce new functions and
new entry points on the way (by template instantiation and virtual
method table generation for instance). */
while (cgraph_nodes_queue)
{
struct cgraph_edge *edge;
tree decl = cgraph_nodes_queue->decl;
node = cgraph_nodes_queue;
cgraph_nodes_queue = cgraph_nodes_queue->next_needed;
node->next_needed = NULL;
/* ??? It is possible to create extern inline function and later using
weak alas attribute to kill its body. See
gcc.c-torture/compile/20011119-1.c */
if (!DECL_SAVED_TREE (decl))
continue;
gcc_assert (!node->analyzed && node->reachable);
gcc_assert (DECL_SAVED_TREE (decl));
cgraph_analyze_function (node);
for (edge = node->callees; edge; edge = edge->next_callee)
if (!edge->callee->reachable)
cgraph_mark_reachable_node (edge->callee);
cgraph_varpool_assemble_pending_decls ();
}
/* Collect entry points to the unit. */
if (cgraph_dump_file)
{
fprintf (cgraph_dump_file, "Unit entry points:");
for (node = cgraph_nodes; node; node = node->next)
if (node->needed && DECL_SAVED_TREE (node->decl))
fprintf (cgraph_dump_file, " %s", cgraph_node_name (node));
fprintf (cgraph_dump_file, "\n\nInitial ");
dump_cgraph (cgraph_dump_file);
}
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "\nReclaiming functions:");
for (node = cgraph_nodes; node; node = node->next)
{
tree decl = node->decl;
if (!node->reachable && DECL_SAVED_TREE (decl))
{
if (cgraph_dump_file)
fprintf (cgraph_dump_file, " %s", cgraph_node_name (node));
cgraph_remove_node (node);
}
else
node->next_needed = NULL;
}
if (cgraph_dump_file)
{
fprintf (cgraph_dump_file, "\n\nReclaimed ");
dump_cgraph (cgraph_dump_file);
}
ggc_collect ();
timevar_pop (TV_CGRAPH);
}
/* Figure out what functions we want to assemble. */
static void
cgraph_mark_functions_to_output (void)
{
struct cgraph_node *node;
for (node = cgraph_nodes; node; node = node->next)
{
tree decl = node->decl;
struct cgraph_edge *e;
gcc_assert (!node->output);
for (e = node->callers; e; e = e->next_caller)
if (e->inline_failed)
break;
/* We need to output all local functions that are used and not
always inlined, as well as those that are reachable from
outside the current compilation unit. */
if (DECL_SAVED_TREE (decl)
&& !node->global.inlined_to
&& (node->needed
|| (e && node->reachable))
&& !TREE_ASM_WRITTEN (decl)
&& !DECL_EXTERNAL (decl))
node->output = 1;
else
{
/* We should've reclaimed all functions that are not needed. */
#ifdef ENABLE_CHECKING
if (!node->global.inlined_to && DECL_SAVED_TREE (decl)
&& !DECL_EXTERNAL (decl))
{
dump_cgraph_node (stderr, node);
internal_error ("failed to reclaim unneeded function");
}
#endif
gcc_assert (node->global.inlined_to || !DECL_SAVED_TREE (decl)
|| DECL_EXTERNAL (decl));
}
}
}
/* Expand function specified by NODE. */
static void
cgraph_expand_function (struct cgraph_node *node)
{
tree decl = node->decl;
/* We ought to not compile any inline clones. */
gcc_assert (!node->global.inlined_to);
if (flag_unit_at_a_time)
announce_function (decl);
/* Generate RTL for the body of DECL. */
lang_hooks.callgraph.expand_function (decl);
/* Make sure that BE didn't give up on compiling. */
/* ??? Can happen with nested function of extern inline. */
gcc_assert (TREE_ASM_WRITTEN (node->decl));
current_function_decl = NULL;
if (!cgraph_preserve_function_body_p (node->decl))
{
DECL_SAVED_TREE (node->decl) = NULL;
DECL_STRUCT_FUNCTION (node->decl) = NULL;
DECL_INITIAL (node->decl) = error_mark_node;
/* Eliminate all call edges. This is important so the call_expr no longer
points to the dead function body. */
cgraph_node_remove_callees (node);
}
}
/* Fill array order with all nodes with output flag set in the reverse
topological order. */
static int
cgraph_postorder (struct cgraph_node **order)
{
struct cgraph_node *node, *node2;
int stack_size = 0;
int order_pos = 0;
struct cgraph_edge *edge, last;
struct cgraph_node **stack =
xcalloc (cgraph_n_nodes, sizeof (struct cgraph_node *));
/* We have to deal with cycles nicely, so use a depth first traversal
output algorithm. Ignore the fact that some functions won't need
to be output and put them into order as well, so we get dependencies
right through intline functions. */
for (node = cgraph_nodes; node; node = node->next)
node->aux = NULL;
for (node = cgraph_nodes; node; node = node->next)
if (!node->aux)
{
node2 = node;
if (!node->callers)
node->aux = &last;
else
node->aux = node->callers;
while (node2)
{
while (node2->aux != &last)
{
edge = node2->aux;
if (edge->next_caller)
node2->aux = edge->next_caller;
else
node2->aux = &last;
if (!edge->caller->aux)
{
if (!edge->caller->callers)
edge->caller->aux = &last;
else
edge->caller->aux = edge->caller->callers;
stack[stack_size++] = node2;
node2 = edge->caller;
break;
}
}
if (node2->aux == &last)
{
order[order_pos++] = node2;
if (stack_size)
node2 = stack[--stack_size];
else
node2 = NULL;
}
}
}
free (stack);
return order_pos;
}
/* Perform reachability analysis and reclaim all unreachable nodes.
This function also remove unneeded bodies of extern inline functions
and thus needs to be done only after inlining decisions has been made. */
static bool
cgraph_remove_unreachable_nodes (void)
{
struct cgraph_node *first = (void *) 1;
struct cgraph_node *node;
bool changed = false;
int insns = 0;
#ifdef ENABLE_CHECKING
verify_cgraph ();
#endif
if (cgraph_dump_file)
fprintf (cgraph_dump_file, "\nReclaiming functions:");
#ifdef ENABLE_CHECKING
for (node = cgraph_nodes; node; node = node->next)
gcc_assert (!node->aux);
#endif
for (node = cgraph_nodes; node; node = node->next)
if (node->needed && !node->global.inlined_to
&& (!DECL_EXTERNAL (node->decl) || !node->analyzed))
{
node->aux = first;
first = node;
}
else
gcc_assert (!node->aux);
/* Perform reachability analysis. As a special case do not consider
extern inline functions not inlined as live because we won't output
them at all. */
while (first != (void *) 1)
{
struct cgraph_edge *e;
node = first;
first = first->aux;
for (e = node->callees; e; e = e->next_callee)
if (!e->callee->aux
&& node->analyzed
&& (!e->inline_failed || !e->callee->analyzed
|| !DECL_EXTERNAL (e->callee->decl)))
{
e->callee->aux = first;
first = e->callee;
}
}
/* Remove unreachable nodes. Extern inline functions need special care;
Unreachable extern inline functions shall be removed.
Reachable extern inline functions we never inlined shall get their bodies
eliminated.
Reachable extern inline functions we sometimes inlined will be turned into
unanalyzed nodes so they look like for true extern functions to the rest
of code. Body of such functions is released via remove_node once the
inline clones are eliminated. */
for (node = cgraph_nodes; node; node = node->next)
{
if (!node->aux)
{
int local_insns;
tree decl = node->decl;
node->global.inlined_to = NULL;
if (DECL_STRUCT_FUNCTION (decl))
local_insns = node->local.self_insns;
else
local_insns = 0;
if (cgraph_dump_file)
fprintf (cgraph_dump_file, " %s", cgraph_node_name (node));
if (!node->analyzed || !DECL_EXTERNAL (node->decl))
cgraph_remove_node (node);
else
{
struct cgraph_edge *e;
for (e = node->callers; e; e = e->next_caller)
if (e->caller->aux)
break;
if (e || node->needed)
{
struct cgraph_node *clone;