8sa1-gcc/gcc/analyzer/analysis-plan.cc
David Malcolm 91f993b7e3 analyzer: use ultimate alias target at calls (PR 93288)
PR analyzer/93288 reports an ICE in a C++ testcase when calling a
constructor.

The issue is that when building the supergraph, we encounter the
cgraph edge to "__ct_comp ", the DECL_COMPLETE_CONSTRUCTOR_P, and
this node's DECL_STRUCT_FUNCTION has a NULL CFG, which the analyzer
reads through, leading to the ICE.

This patch reworks function and fndecl lookup at calls throughout the
analyzer so that it looks for the ultimate_alias_target of the callee.
In the case above, this means using the "__ct_base " for the ctor,
which has a CFG, fixing the ICE.

Getting this right allows for some simple C++ cases involving ctors to
work, so the patch also adds some test coverage for that.

gcc/analyzer/ChangeLog:
	PR analyzer/93288
	* analysis-plan.cc (analysis_plan::use_summary_p): Look through
	the ultimate_alias_target when getting the called function.
	* engine.cc (exploded_node::on_stmt): Rename second "ctxt" to
	"sm_ctxt".  Use the region_model's get_fndecl_for_call rather than
	gimple_call_fndecl.
	* region-model.cc (region_model::get_fndecl_for_call): Use
	ultimate_alias_target on fndecl.
	* supergraph.cc (get_ultimate_function_for_cgraph_edge): New
	function.
	(supergraph_call_edge): Use it when rejecting edges without
	functions.
	(supergraph::supergraph): Use it to get the function for the
	cgraph_edge when building interprocedural superedges.
	(callgraph_superedge::get_callee_function):  Use it.
	* supergraph.h (supergraph::get_num_snodes): Make param const.
	(supergraph::function_to_num_snodes_t): Make first type param
	const.

gcc/testsuite/ChangeLog:
	PR analyzer/93288
	* g++.dg/analyzer/malloc.C: Add test coverage for a double-free
	called in a constructor.
	* g++.dg/analyzer/pr93288.C: New test.
2020-02-11 21:06:43 -05:00

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/* A class to encapsulate decisions about how the analysis should happen.
Copyright (C) 2019-2020 Free Software Foundation, Inc.
Contributed by David Malcolm <dmalcolm@redhat.com>.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tree.h"
#include "options.h"
#include "cgraph.h"
#include "timevar.h"
#include "ipa-utils.h"
#include "function.h"
#include "analyzer/analyzer.h"
#include "diagnostic-core.h"
#include "analyzer/analyzer-logging.h"
#include "analyzer/analysis-plan.h"
#include "ordered-hash-map.h"
#include "options.h"
#include "cgraph.h"
#include "function.h"
#include "cfg.h"
#include "basic-block.h"
#include "gimple.h"
#include "gimple-iterator.h"
#include "digraph.h"
#include "analyzer/supergraph.h"
#if ENABLE_ANALYZER
/* class analysis_plan. */
/* analysis_plan's ctor. */
analysis_plan::analysis_plan (const supergraph &sg, logger *logger)
: log_user (logger), m_sg (sg),
m_cgraph_node_postorder (XCNEWVEC (struct cgraph_node *,
symtab->cgraph_count)),
m_index_by_uid (symtab->cgraph_max_uid)
{
LOG_SCOPE (logger);
auto_timevar time (TV_ANALYZER_PLAN);
m_num_cgraph_nodes = ipa_reverse_postorder (m_cgraph_node_postorder);
gcc_assert (m_num_cgraph_nodes == symtab->cgraph_count);
if (get_logger_file ())
ipa_print_order (get_logger_file (),
"analysis_plan", m_cgraph_node_postorder,
m_num_cgraph_nodes);
/* Populate m_index_by_uid. */
for (int i = 0; i < symtab->cgraph_max_uid; i++)
m_index_by_uid.quick_push (-1);
for (int i = 0; i < m_num_cgraph_nodes; i++)
{
gcc_assert (m_cgraph_node_postorder[i]->get_uid ()
< symtab->cgraph_max_uid);
m_index_by_uid[m_cgraph_node_postorder[i]->get_uid ()] = i;
}
}
/* analysis_plan's dtor. */
analysis_plan::~analysis_plan ()
{
free (m_cgraph_node_postorder);
}
/* Comparator for use by the exploded_graph's worklist, to order FUN_A
and FUN_B so that functions that are to be summarized are visited
before the summary is needed (based on a sort of the callgraph). */
int
analysis_plan::cmp_function (function *fun_a, function *fun_b) const
{
cgraph_node *node_a = cgraph_node::get (fun_a->decl);
cgraph_node *node_b = cgraph_node::get (fun_b->decl);
int idx_a = m_index_by_uid[node_a->get_uid ()];
int idx_b = m_index_by_uid[node_b->get_uid ()];
return idx_b - idx_a;
}
/* Return true if the call EDGE should be analyzed using a call summary.
Return false if it should be analyzed using a full call and return. */
bool
analysis_plan::use_summary_p (const cgraph_edge *edge) const
{
/* Don't use call summaries if -fno-analyzer-call-summaries. */
if (!flag_analyzer_call_summaries)
return false;
/* TODO: don't count callsites each time. */
int num_call_sites = 0;
const cgraph_node *callee = edge->callee;
for (cgraph_edge *edge = callee->callers; edge; edge = edge->next_caller)
++num_call_sites;
/* Don't use a call summary if there's only one call site. */
if (num_call_sites <= 1)
return false;
/* Require the callee to be sufficiently complex to be worth
summarizing. */
const function *fun
= const_cast <cgraph_node *> (callee)->ultimate_alias_target ()->get_fun ();
/* TODO(stage1): can ultimate_alias_target be made const? */
if ((int)m_sg.get_num_snodes (fun)
< param_analyzer_min_snodes_for_call_summary)
return false;
return true;
}
#endif /* #if ENABLE_ANALYZER */