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/* Tree lowering pass. This pass gimplifies the tree representation built
by the C-based front ends. The structure of gimplified, or
language-independent, trees is dictated by the grammar described in this
file.
Copyright (C) 2002-2014 Free Software Foundation, Inc.
Lowering of expressions contributed by Sebastian Pop <s.pop@laposte.net>
Re-written to support lowering of whole function trees, documentation
and miscellaneous cleanups by Diego Novillo <dnovillo@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 "tm.h"
#include "tree.h"
#include "c-common.h"
#include "basic-block.h"
#include "tree-ssa-alias.h"
#include "internal-fn.h"
#include "gimple-expr.h"
#include "is-a.h"
#include "gimple.h"
#include "gimplify.h"
#include "tree-inline.h"
#include "diagnostic-core.h"
#include "langhooks.h"
#include "langhooks-def.h"
#include "flags.h"
#include "dumpfile.h"
#include "c-pretty-print.h"
#include "cgraph.h"
#include "cilk.h"
#include "c-ubsan.h"
#include "pointer-set.h"
/* The gimplification pass converts the language-dependent trees
(ld-trees) emitted by the parser into language-independent trees
(li-trees) that are the target of SSA analysis and transformations.
Language-independent trees are based on the SIMPLE intermediate
representation used in the McCAT compiler framework:
"Designing the McCAT Compiler Based on a Family of Structured
Intermediate Representations,"
L. Hendren, C. Donawa, M. Emami, G. Gao, Justiani, and B. Sridharan,
Proceedings of the 5th International Workshop on Languages and
Compilers for Parallel Computing, no. 757 in Lecture Notes in
Computer Science, New Haven, Connecticut, pp. 406-420,
Springer-Verlag, August 3-5, 1992.
http://www-acaps.cs.mcgill.ca/info/McCAT/McCAT.html
Basically, we walk down gimplifying the nodes that we encounter. As we
walk back up, we check that they fit our constraints, and copy them
into temporaries if not. */
/* Callback for c_genericize. */
static tree
ubsan_walk_array_refs_r (tree *tp, int *walk_subtrees, void *data)
{
struct pointer_set_t *pset = (struct pointer_set_t *) data;
/* Since walk_tree doesn't call the callback function on the decls
in BIND_EXPR_VARS, we have to walk them manually. */
if (TREE_CODE (*tp) == BIND_EXPR)
{
for (tree decl = BIND_EXPR_VARS (*tp); decl; decl = DECL_CHAIN (decl))
{
if (TREE_STATIC (decl))
{
*walk_subtrees = 0;
continue;
}
walk_tree (&DECL_INITIAL (decl), ubsan_walk_array_refs_r, pset,
pset);
walk_tree (&DECL_SIZE (decl), ubsan_walk_array_refs_r, pset, pset);
walk_tree (&DECL_SIZE_UNIT (decl), ubsan_walk_array_refs_r, pset,
pset);
}
}
else if (TREE_CODE (*tp) == ADDR_EXPR
&& TREE_CODE (TREE_OPERAND (*tp, 0)) == ARRAY_REF)
ubsan_maybe_instrument_array_ref (&TREE_OPERAND (*tp, 0), true);
else if (TREE_CODE (*tp) == ARRAY_REF)
ubsan_maybe_instrument_array_ref (tp, false);
return NULL_TREE;
}
/* Gimplification of statement trees. */
/* Convert the tree representation of FNDECL from C frontend trees to
GENERIC. */
void
c_genericize (tree fndecl)
{
FILE *dump_orig;
int local_dump_flags;
struct cgraph_node *cgn;
if (flag_sanitize & SANITIZE_BOUNDS)
{
struct pointer_set_t *pset = pointer_set_create ();
walk_tree (&DECL_SAVED_TREE (fndecl), ubsan_walk_array_refs_r, pset,
pset);
pointer_set_destroy (pset);
}
/* Dump the C-specific tree IR. */
dump_orig = get_dump_info (TDI_original, &local_dump_flags);
if (dump_orig)
{
fprintf (dump_orig, "\n;; Function %s",
lang_hooks.decl_printable_name (fndecl, 2));
fprintf (dump_orig, " (%s)\n",
(!DECL_ASSEMBLER_NAME_SET_P (fndecl) ? "null"
: IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl))));
fprintf (dump_orig, ";; enabled by -%s\n", dump_flag_name (TDI_original));
fprintf (dump_orig, "\n");
if (local_dump_flags & TDF_RAW)
dump_node (DECL_SAVED_TREE (fndecl),
TDF_SLIM | local_dump_flags, dump_orig);
else
print_c_tree (dump_orig, DECL_SAVED_TREE (fndecl));
fprintf (dump_orig, "\n");
}
/* Dump all nested functions now. */
cgn = cgraph_get_create_node (fndecl);
for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested)
c_genericize (cgn->decl);
}
static void
add_block_to_enclosing (tree block)
{
unsigned i;
tree enclosing;
gimple bind;
vec<gimple> stack = gimple_bind_expr_stack ();
FOR_EACH_VEC_ELT (stack, i, bind)
if (gimple_bind_block (bind))
break;
enclosing = gimple_bind_block (bind);
BLOCK_SUBBLOCKS (enclosing) = chainon (BLOCK_SUBBLOCKS (enclosing), block);
}
/* Genericize a scope by creating a new BIND_EXPR.
BLOCK is either a BLOCK representing the scope or a chain of _DECLs.
In the latter case, we need to create a new BLOCK and add it to the
BLOCK_SUBBLOCKS of the enclosing block.
BODY is a chain of C _STMT nodes for the contents of the scope, to be
genericized. */
tree
c_build_bind_expr (location_t loc, tree block, tree body)
{
tree decls, bind;
if (block == NULL_TREE)
decls = NULL_TREE;
else if (TREE_CODE (block) == BLOCK)
decls = BLOCK_VARS (block);
else
{
decls = block;
if (DECL_ARTIFICIAL (decls))
block = NULL_TREE;
else
{
block = make_node (BLOCK);
BLOCK_VARS (block) = decls;
add_block_to_enclosing (block);
}
}
if (!body)
body = build_empty_stmt (loc);
if (decls || block)
{
bind = build3 (BIND_EXPR, void_type_node, decls, body, block);
TREE_SIDE_EFFECTS (bind) = 1;
SET_EXPR_LOCATION (bind, loc);
}
else
bind = body;
return bind;
}
/* Gimplification of expression trees. */
/* Do C-specific gimplification on *EXPR_P. PRE_P and POST_P are as in
gimplify_expr. */
int
c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED,
gimple_seq *post_p ATTRIBUTE_UNUSED)
{
enum tree_code code = TREE_CODE (*expr_p);
switch (code)
{
case DECL_EXPR:
/* This is handled mostly by gimplify.c, but we have to deal with
not warning about int x = x; as it is a GCC extension to turn off
this warning but only if warn_init_self is zero. */
if (TREE_CODE (DECL_EXPR_DECL (*expr_p)) == VAR_DECL
&& !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p))
&& !TREE_STATIC (DECL_EXPR_DECL (*expr_p))
&& (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) == DECL_EXPR_DECL (*expr_p))
&& !warn_init_self)
TREE_NO_WARNING (DECL_EXPR_DECL (*expr_p)) = 1;
break;
case PREINCREMENT_EXPR:
case PREDECREMENT_EXPR:
case POSTINCREMENT_EXPR:
case POSTDECREMENT_EXPR:
{
tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
{
if (!TYPE_OVERFLOW_WRAPS (type))
type = unsigned_type_for (type);
return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
}
break;
}
case CILK_SPAWN_STMT:
gcc_assert
(fn_contains_cilk_spawn_p (cfun)
&& cilk_detect_spawn_and_unwrap (expr_p));
/* If errors are seen, then just process it as a CALL_EXPR. */
if (!seen_error ())
return (enum gimplify_status) gimplify_cilk_spawn (expr_p);
case MODIFY_EXPR:
case INIT_EXPR:
case CALL_EXPR:
if (fn_contains_cilk_spawn_p (cfun)
&& cilk_detect_spawn_and_unwrap (expr_p)
/* If an error is found, the spawn wrapper is removed and the
original expression (MODIFY/INIT/CALL_EXPR) is processes as
it is supposed to be. */
&& !seen_error ())
return (enum gimplify_status) gimplify_cilk_spawn (expr_p);
default:;
}
return GS_UNHANDLED;
}
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