c-gimplify.c revision 169689
1/* Tree lowering pass. This pass gimplifies the tree representation built 2 by the C-based front ends. The structure of gimplified, or 3 language-independent, trees is dictated by the grammar described in this 4 file. 5 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. 6 Lowering of expressions contributed by Sebastian Pop <s.pop@laposte.net> 7 Re-written to support lowering of whole function trees, documentation 8 and miscellaneous cleanups by Diego Novillo <dnovillo@redhat.com> 9 10This file is part of GCC. 11 12GCC is free software; you can redistribute it and/or modify it under 13the terms of the GNU General Public License as published by the Free 14Software Foundation; either version 2, or (at your option) any later 15version. 16 17GCC is distributed in the hope that it will be useful, but WITHOUT ANY 18WARRANTY; without even the implied warranty of MERCHANTABILITY or 19FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 20for more details. 21 22You should have received a copy of the GNU General Public License 23along with GCC; see the file COPYING. If not, write to the Free 24Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 2502110-1301, USA. */ 26 27#include "config.h" 28#include "system.h" 29#include "coretypes.h" 30#include "tm.h" 31#include "tree.h" 32#include "varray.h" 33#include "c-tree.h" 34#include "c-common.h" 35#include "tree-gimple.h" 36#include "hard-reg-set.h" 37#include "basic-block.h" 38#include "tree-flow.h" 39#include "tree-inline.h" 40#include "diagnostic.h" 41#include "langhooks.h" 42#include "langhooks-def.h" 43#include "flags.h" 44#include "rtl.h" 45#include "toplev.h" 46#include "tree-dump.h" 47#include "c-pretty-print.h" 48#include "cgraph.h" 49 50 51/* The gimplification pass converts the language-dependent trees 52 (ld-trees) emitted by the parser into language-independent trees 53 (li-trees) that are the target of SSA analysis and transformations. 54 55 Language-independent trees are based on the SIMPLE intermediate 56 representation used in the McCAT compiler framework: 57 58 "Designing the McCAT Compiler Based on a Family of Structured 59 Intermediate Representations," 60 L. Hendren, C. Donawa, M. Emami, G. Gao, Justiani, and B. Sridharan, 61 Proceedings of the 5th International Workshop on Languages and 62 Compilers for Parallel Computing, no. 757 in Lecture Notes in 63 Computer Science, New Haven, Connecticut, pp. 406-420, 64 Springer-Verlag, August 3-5, 1992. 65 66 http://www-acaps.cs.mcgill.ca/info/McCAT/McCAT.html 67 68 Basically, we walk down gimplifying the nodes that we encounter. As we 69 walk back up, we check that they fit our constraints, and copy them 70 into temporaries if not. */ 71 72/* Gimplification of statement trees. */ 73 74/* Convert the tree representation of FNDECL from C frontend trees to 75 GENERIC. */ 76 77void 78c_genericize (tree fndecl) 79{ 80 FILE *dump_orig; 81 int local_dump_flags; 82 struct cgraph_node *cgn; 83 84 /* Dump the C-specific tree IR. */ 85 dump_orig = dump_begin (TDI_original, &local_dump_flags); 86 if (dump_orig) 87 { 88 fprintf (dump_orig, "\n;; Function %s", 89 lang_hooks.decl_printable_name (fndecl, 2)); 90 fprintf (dump_orig, " (%s)\n", 91 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (fndecl))); 92 fprintf (dump_orig, ";; enabled by -%s\n", dump_flag_name (TDI_original)); 93 fprintf (dump_orig, "\n"); 94 95 if (local_dump_flags & TDF_RAW) 96 dump_node (DECL_SAVED_TREE (fndecl), 97 TDF_SLIM | local_dump_flags, dump_orig); 98 else 99 print_c_tree (dump_orig, DECL_SAVED_TREE (fndecl)); 100 fprintf (dump_orig, "\n"); 101 102 dump_end (TDI_original, dump_orig); 103 } 104 105 /* Go ahead and gimplify for now. */ 106 gimplify_function_tree (fndecl); 107 108 /* Dump the genericized tree IR. */ 109 dump_function (TDI_generic, fndecl); 110 111 /* Genericize all nested functions now. We do things in this order so 112 that items like VLA sizes are expanded properly in the context of 113 the correct function. */ 114 cgn = cgraph_node (fndecl); 115 for (cgn = cgn->nested; cgn ; cgn = cgn->next_nested) 116 c_genericize (cgn->decl); 117} 118 119static void 120add_block_to_enclosing (tree block) 121{ 122 tree enclosing; 123 124 for (enclosing = gimple_current_bind_expr (); 125 enclosing; enclosing = TREE_CHAIN (enclosing)) 126 if (BIND_EXPR_BLOCK (enclosing)) 127 break; 128 129 enclosing = BIND_EXPR_BLOCK (enclosing); 130 BLOCK_SUBBLOCKS (enclosing) = chainon (BLOCK_SUBBLOCKS (enclosing), block); 131} 132 133/* Genericize a scope by creating a new BIND_EXPR. 134 BLOCK is either a BLOCK representing the scope or a chain of _DECLs. 135 In the latter case, we need to create a new BLOCK and add it to the 136 BLOCK_SUBBLOCKS of the enclosing block. 137 BODY is a chain of C _STMT nodes for the contents of the scope, to be 138 genericized. */ 139 140tree 141c_build_bind_expr (tree block, tree body) 142{ 143 tree decls, bind; 144 145 if (block == NULL_TREE) 146 decls = NULL_TREE; 147 else if (TREE_CODE (block) == BLOCK) 148 decls = BLOCK_VARS (block); 149 else 150 { 151 decls = block; 152 if (DECL_ARTIFICIAL (decls)) 153 block = NULL_TREE; 154 else 155 { 156 block = make_node (BLOCK); 157 BLOCK_VARS (block) = decls; 158 add_block_to_enclosing (block); 159 } 160 } 161 162 if (!body) 163 body = build_empty_stmt (); 164 if (decls || block) 165 { 166 bind = build3 (BIND_EXPR, void_type_node, decls, body, block); 167 TREE_SIDE_EFFECTS (bind) = 1; 168 } 169 else 170 bind = body; 171 172 return bind; 173} 174 175/* Gimplification of expression trees. */ 176 177/* Gimplify a C99 compound literal expression. This just means adding 178 the DECL_EXPR before the current statement and using its anonymous 179 decl instead. */ 180 181static enum gimplify_status 182gimplify_compound_literal_expr (tree *expr_p, tree *pre_p) 183{ 184 tree decl_s = COMPOUND_LITERAL_EXPR_DECL_STMT (*expr_p); 185 tree decl = DECL_EXPR_DECL (decl_s); 186 187 /* This decl isn't mentioned in the enclosing block, so add it to the 188 list of temps. FIXME it seems a bit of a kludge to say that 189 anonymous artificial vars aren't pushed, but everything else is. */ 190 if (DECL_NAME (decl) == NULL_TREE && !DECL_SEEN_IN_BIND_EXPR_P (decl)) 191 gimple_add_tmp_var (decl); 192 193 gimplify_and_add (decl_s, pre_p); 194 *expr_p = decl; 195 return GS_OK; 196} 197 198/* Do C-specific gimplification. Args are as for gimplify_expr. */ 199 200int 201c_gimplify_expr (tree *expr_p, tree *pre_p, tree *post_p ATTRIBUTE_UNUSED) 202{ 203 enum tree_code code = TREE_CODE (*expr_p); 204 205 switch (code) 206 { 207 case DECL_EXPR: 208 /* This is handled mostly by gimplify.c, but we have to deal with 209 not warning about int x = x; as it is a GCC extension to turn off 210 this warning but only if warn_init_self is zero. */ 211 if (TREE_CODE (DECL_EXPR_DECL (*expr_p)) == VAR_DECL 212 && !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p)) 213 && !TREE_STATIC (DECL_EXPR_DECL (*expr_p)) 214 && (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) 215 == DECL_EXPR_DECL (*expr_p)) 216 && !warn_init_self) 217 TREE_NO_WARNING (DECL_EXPR_DECL (*expr_p)) = 1; 218 return GS_UNHANDLED; 219 220 case COMPOUND_LITERAL_EXPR: 221 return gimplify_compound_literal_expr (expr_p, pre_p); 222 223 default: 224 return GS_UNHANDLED; 225 } 226} 227