| /* 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) 2002-2018 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 "function.h" |
| #include "basic-block.h" |
| #include "tree.h" |
| #include "gimple.h" |
| #include "cgraph.h" |
| #include "c-pretty-print.h" |
| #include "gimplify.h" |
| #include "langhooks.h" |
| #include "dumpfile.h" |
| #include "c-ubsan.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) |
| { |
| hash_set<tree> *pset = (hash_set<tree> *) data; |
| |
| if (TREE_CODE (*tp) == BIND_EXPR) |
| { |
| /* Since walk_tree doesn't call the callback function on the decls |
| in BIND_EXPR_VARS, we have to walk them manually, so we can avoid |
| instrumenting DECL_INITIAL of TREE_STATIC vars. */ |
| *walk_subtrees = 0; |
| for (tree decl = BIND_EXPR_VARS (*tp); decl; decl = DECL_CHAIN (decl)) |
| { |
| if (TREE_STATIC (decl)) |
| 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); |
| } |
| walk_tree (&BIND_EXPR_BODY (*tp), 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); |
| /* Make sure ubsan_maybe_instrument_array_ref is not called again |
| on the ARRAY_REF, the above call might not instrument anything |
| as the index might be constant or masked, so ensure it is not |
| walked again and walk its subtrees manually. */ |
| tree aref = TREE_OPERAND (*tp, 0); |
| pset->add (aref); |
| *walk_subtrees = 0; |
| walk_tree (&TREE_OPERAND (aref, 0), ubsan_walk_array_refs_r, pset, pset); |
| walk_tree (&TREE_OPERAND (aref, 1), ubsan_walk_array_refs_r, pset, pset); |
| walk_tree (&TREE_OPERAND (aref, 2), ubsan_walk_array_refs_r, pset, pset); |
| walk_tree (&TREE_OPERAND (aref, 3), ubsan_walk_array_refs_r, pset, pset); |
| } |
| 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; |
| dump_flags_t local_dump_flags; |
| struct cgraph_node *cgn; |
| |
| if (flag_sanitize & SANITIZE_BOUNDS) |
| { |
| hash_set<tree> pset; |
| walk_tree (&DECL_SAVED_TREE (fndecl), ubsan_walk_array_refs_r, &pset, |
| &pset); |
| } |
| |
| if (warn_duplicated_branches) |
| walk_tree_without_duplicates (&DECL_SAVED_TREE (fndecl), |
| do_warn_duplicated_branches_r, NULL); |
| |
| /* 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_node::get_create (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; |
| gbind *bind; |
| vec<gbind *> 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 LSHIFT_EXPR: |
| case RSHIFT_EXPR: |
| case LROTATE_EXPR: |
| case RROTATE_EXPR: |
| { |
| /* We used to convert the right operand of a shift-expression |
| to an integer_type_node in the FEs. But it is unnecessary |
| and not desirable for diagnostics and sanitizers. We keep |
| this here to not pessimize the code, but we convert to an |
| unsigned type, because negative shift counts are undefined |
| anyway. |
| We should get rid of this conversion when we have a proper |
| type demotion/promotion pass. */ |
| tree *op1_p = &TREE_OPERAND (*expr_p, 1); |
| if (!VECTOR_TYPE_P (TREE_TYPE (*op1_p)) |
| && !types_compatible_p (TYPE_MAIN_VARIANT (TREE_TYPE (*op1_p)), |
| unsigned_type_node) |
| && !types_compatible_p (TYPE_MAIN_VARIANT (TREE_TYPE (*op1_p)), |
| integer_type_node)) |
| /* Make sure to unshare the result, tree sharing is invalid |
| during gimplification. */ |
| *op1_p = unshare_expr (convert (unsigned_type_node, *op1_p)); |
| break; |
| } |
| |
| 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 (VAR_P (DECL_EXPR_DECL (*expr_p)) |
| && !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; |
| } |
| |
| default:; |
| } |
| |
| return GS_UNHANDLED; |
| } |