308 lines
9.7 KiB
C
308 lines
9.7 KiB
C
/* Tree lowering pass. This pass gimplifies the tree representation built
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by the C-based front ends. The structure of gimplified, or
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language-independent, trees is dictated by the grammar described in this
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file.
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Copyright (C) 2002-2017 Free Software Foundation, Inc.
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Lowering of expressions contributed by Sebastian Pop <s.pop@laposte.net>
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Re-written to support lowering of whole function trees, documentation
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and miscellaneous cleanups by Diego Novillo <dnovillo@redhat.com>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "function.h"
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#include "basic-block.h"
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#include "tree.h"
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#include "gimple.h"
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#include "cgraph.h"
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#include "c-pretty-print.h"
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#include "gimplify.h"
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#include "langhooks.h"
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#include "dumpfile.h"
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#include "cilk.h"
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#include "c-ubsan.h"
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/* The gimplification pass converts the language-dependent trees
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(ld-trees) emitted by the parser into language-independent trees
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(li-trees) that are the target of SSA analysis and transformations.
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Language-independent trees are based on the SIMPLE intermediate
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representation used in the McCAT compiler framework:
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"Designing the McCAT Compiler Based on a Family of Structured
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Intermediate Representations,"
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L. Hendren, C. Donawa, M. Emami, G. Gao, Justiani, and B. Sridharan,
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Proceedings of the 5th International Workshop on Languages and
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Compilers for Parallel Computing, no. 757 in Lecture Notes in
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Computer Science, New Haven, Connecticut, pp. 406-420,
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Springer-Verlag, August 3-5, 1992.
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http://www-acaps.cs.mcgill.ca/info/McCAT/McCAT.html
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Basically, we walk down gimplifying the nodes that we encounter. As we
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walk back up, we check that they fit our constraints, and copy them
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into temporaries if not. */
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/* Callback for c_genericize. */
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static tree
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ubsan_walk_array_refs_r (tree *tp, int *walk_subtrees, void *data)
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{
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hash_set<tree> *pset = (hash_set<tree> *) data;
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if (TREE_CODE (*tp) == BIND_EXPR)
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{
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/* Since walk_tree doesn't call the callback function on the decls
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in BIND_EXPR_VARS, we have to walk them manually, so we can avoid
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instrumenting DECL_INITIAL of TREE_STATIC vars. */
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*walk_subtrees = 0;
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for (tree decl = BIND_EXPR_VARS (*tp); decl; decl = DECL_CHAIN (decl))
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{
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if (TREE_STATIC (decl))
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continue;
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walk_tree (&DECL_INITIAL (decl), ubsan_walk_array_refs_r, pset,
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pset);
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walk_tree (&DECL_SIZE (decl), ubsan_walk_array_refs_r, pset, pset);
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walk_tree (&DECL_SIZE_UNIT (decl), ubsan_walk_array_refs_r, pset,
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pset);
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}
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walk_tree (&BIND_EXPR_BODY (*tp), ubsan_walk_array_refs_r, pset, pset);
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}
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else if (TREE_CODE (*tp) == ADDR_EXPR
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&& TREE_CODE (TREE_OPERAND (*tp, 0)) == ARRAY_REF)
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{
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ubsan_maybe_instrument_array_ref (&TREE_OPERAND (*tp, 0), true);
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/* Make sure ubsan_maybe_instrument_array_ref is not called again
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on the ARRAY_REF, the above call might not instrument anything
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as the index might be constant or masked, so ensure it is not
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walked again and walk its subtrees manually. */
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tree aref = TREE_OPERAND (*tp, 0);
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pset->add (aref);
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*walk_subtrees = 0;
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walk_tree (&TREE_OPERAND (aref, 0), ubsan_walk_array_refs_r, pset, pset);
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walk_tree (&TREE_OPERAND (aref, 1), ubsan_walk_array_refs_r, pset, pset);
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walk_tree (&TREE_OPERAND (aref, 2), ubsan_walk_array_refs_r, pset, pset);
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walk_tree (&TREE_OPERAND (aref, 3), ubsan_walk_array_refs_r, pset, pset);
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}
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else if (TREE_CODE (*tp) == ARRAY_REF)
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ubsan_maybe_instrument_array_ref (tp, false);
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return NULL_TREE;
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}
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/* Gimplification of statement trees. */
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/* Convert the tree representation of FNDECL from C frontend trees to
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GENERIC. */
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void
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c_genericize (tree fndecl)
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{
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FILE *dump_orig;
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int local_dump_flags;
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struct cgraph_node *cgn;
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if (flag_sanitize & SANITIZE_BOUNDS)
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{
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hash_set<tree> pset;
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walk_tree (&DECL_SAVED_TREE (fndecl), ubsan_walk_array_refs_r, &pset,
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&pset);
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}
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if (warn_duplicated_branches)
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walk_tree_without_duplicates (&DECL_SAVED_TREE (fndecl),
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do_warn_duplicated_branches_r, NULL);
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/* Dump the C-specific tree IR. */
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dump_orig = get_dump_info (TDI_original, &local_dump_flags);
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if (dump_orig)
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{
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fprintf (dump_orig, "\n;; Function %s",
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lang_hooks.decl_printable_name (fndecl, 2));
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fprintf (dump_orig, " (%s)\n",
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(!DECL_ASSEMBLER_NAME_SET_P (fndecl) ? "null"
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: IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl))));
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fprintf (dump_orig, ";; enabled by -%s\n", dump_flag_name (TDI_original));
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fprintf (dump_orig, "\n");
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if (local_dump_flags & TDF_RAW)
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dump_node (DECL_SAVED_TREE (fndecl),
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TDF_SLIM | local_dump_flags, dump_orig);
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else
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print_c_tree (dump_orig, DECL_SAVED_TREE (fndecl));
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fprintf (dump_orig, "\n");
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}
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/* Dump all nested functions now. */
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cgn = cgraph_node::get_create (fndecl);
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for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested)
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c_genericize (cgn->decl);
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}
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static void
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add_block_to_enclosing (tree block)
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{
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unsigned i;
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tree enclosing;
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gbind *bind;
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vec<gbind *> stack = gimple_bind_expr_stack ();
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FOR_EACH_VEC_ELT (stack, i, bind)
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if (gimple_bind_block (bind))
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break;
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enclosing = gimple_bind_block (bind);
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BLOCK_SUBBLOCKS (enclosing) = chainon (BLOCK_SUBBLOCKS (enclosing), block);
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}
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/* Genericize a scope by creating a new BIND_EXPR.
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BLOCK is either a BLOCK representing the scope or a chain of _DECLs.
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In the latter case, we need to create a new BLOCK and add it to the
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BLOCK_SUBBLOCKS of the enclosing block.
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BODY is a chain of C _STMT nodes for the contents of the scope, to be
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genericized. */
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tree
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c_build_bind_expr (location_t loc, tree block, tree body)
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{
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tree decls, bind;
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if (block == NULL_TREE)
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decls = NULL_TREE;
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else if (TREE_CODE (block) == BLOCK)
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decls = BLOCK_VARS (block);
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else
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{
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decls = block;
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if (DECL_ARTIFICIAL (decls))
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block = NULL_TREE;
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else
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{
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block = make_node (BLOCK);
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BLOCK_VARS (block) = decls;
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add_block_to_enclosing (block);
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}
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}
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if (!body)
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body = build_empty_stmt (loc);
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if (decls || block)
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{
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bind = build3 (BIND_EXPR, void_type_node, decls, body, block);
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TREE_SIDE_EFFECTS (bind) = 1;
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SET_EXPR_LOCATION (bind, loc);
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}
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else
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bind = body;
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return bind;
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}
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/* Gimplification of expression trees. */
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/* Do C-specific gimplification on *EXPR_P. PRE_P and POST_P are as in
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gimplify_expr. */
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int
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c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED,
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gimple_seq *post_p ATTRIBUTE_UNUSED)
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{
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enum tree_code code = TREE_CODE (*expr_p);
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switch (code)
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{
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case LSHIFT_EXPR:
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case RSHIFT_EXPR:
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{
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/* We used to convert the right operand of a shift-expression
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to an integer_type_node in the FEs. But it is unnecessary
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and not desirable for diagnostics and sanitizers. We keep
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this here to not pessimize the code, but we convert to an
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unsigned type, because negative shift counts are undefined
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anyway.
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We should get rid of this conversion when we have a proper
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type demotion/promotion pass. */
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tree *op1_p = &TREE_OPERAND (*expr_p, 1);
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if (!VECTOR_TYPE_P (TREE_TYPE (*op1_p))
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&& !types_compatible_p (TYPE_MAIN_VARIANT (TREE_TYPE (*op1_p)),
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unsigned_type_node)
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&& !types_compatible_p (TYPE_MAIN_VARIANT (TREE_TYPE (*op1_p)),
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integer_type_node))
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*op1_p = convert (unsigned_type_node, *op1_p);
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break;
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}
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case DECL_EXPR:
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/* This is handled mostly by gimplify.c, but we have to deal with
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not warning about int x = x; as it is a GCC extension to turn off
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this warning but only if warn_init_self is zero. */
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if (VAR_P (DECL_EXPR_DECL (*expr_p))
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&& !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p))
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&& !TREE_STATIC (DECL_EXPR_DECL (*expr_p))
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&& (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) == DECL_EXPR_DECL (*expr_p))
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&& !warn_init_self)
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TREE_NO_WARNING (DECL_EXPR_DECL (*expr_p)) = 1;
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break;
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case PREINCREMENT_EXPR:
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case PREDECREMENT_EXPR:
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case POSTINCREMENT_EXPR:
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case POSTDECREMENT_EXPR:
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{
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tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 0));
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if (INTEGRAL_TYPE_P (type) && c_promoting_integer_type_p (type))
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{
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if (!TYPE_OVERFLOW_WRAPS (type))
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type = unsigned_type_for (type);
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return gimplify_self_mod_expr (expr_p, pre_p, post_p, 1, type);
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}
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break;
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}
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case CILK_SPAWN_STMT:
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gcc_assert(fn_contains_cilk_spawn_p (cfun)
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&& cilk_detect_spawn_and_unwrap (expr_p));
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if (!seen_error ())
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{
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cilk_gimplify_call_params_in_spawned_fn (expr_p, pre_p);
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return (enum gimplify_status) gimplify_cilk_spawn (expr_p);
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}
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return GS_ERROR;
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case MODIFY_EXPR:
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case INIT_EXPR:
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case CALL_EXPR:
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if (fn_contains_cilk_spawn_p (cfun)
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&& cilk_detect_spawn_and_unwrap (expr_p)
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/* If an error is found, the spawn wrapper is removed and the
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original expression (MODIFY/INIT/CALL_EXPR) is processes as
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it is supposed to be. */
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&& !seen_error ())
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{
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cilk_gimplify_call_params_in_spawned_fn (expr_p, pre_p);
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return (enum gimplify_status) gimplify_cilk_spawn (expr_p);
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}
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default:;
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}
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return GS_UNHANDLED;
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}
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