/* Code to test for "definitive assignment". Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc. This program 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 2, or (at your option) any later version. This program 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 GNU CC; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. Java and all Java-based marks are trademarks or registered trademarks of Sun Microsystems, Inc. in the United States and other countries. The Free Software Foundation is independent of Sun Microsystems, Inc. */ /* Written by Per Bothner , January 1999. */ #include "config.h" #include "system.h" #include "tree.h" #include "flags.h" /* Needed for optimize. */ #include "java-tree.h" #include "toplev.h" /* Needed for fatal. */ /* The basic idea is that we assign each local variable declaration an index, and then we pass around bitstrings, where the i'th bit is set if decl whose DECL_BIT_INDEX is i is definitely assigned. */ /* One segment of a bitstring. */ typedef unsigned int word; /* Pointer to a bitstring. */ typedef word *words; /* Number of locals variables currently active. */ int num_current_locals = 0; /* The index of the first local variable in the current block. The variables whose DECL_BIT_INDEX are in the range from start_current_locals (inclusive) up to num_current_locals (exclusive) are declared in the "current" block. If there is a loop or branch form, we set start_current_locals to num_current_locals to indicate there is no current block. The point is that if a variable in the current block is set, there are no other control paths that we have to worry about. Hence, we can remove it from the set of variables we are checking, making its bit index available for some other variable. For simplicity, we only do that if the variable's bit index is (num_current_locals-1); freeing up its bit index is then just a simple matter of decrementing num_current_locals. The reason this is worth doing is that it is simple, and allows us to use short (usually one-word) bit-strings, even for methods with thousands of local variables, as long as most of them are initialized immediately after or in their declaration. */ int start_current_locals = 0; int num_current_words = 1; static tree wfl; #define COPYN(DST, SRC, NWORDS) memcpy (DST, SRC, NWORDS * sizeof(word)) #define COPY(DST, SRC) COPYN (DST, SRC, num_current_words) #define SET_ALL(DST) memset (DST, ~0, num_current_words * sizeof(word)) #define CLEAR_ALL(DST) memset (DST, 0, num_current_words * sizeof(word)) #define INTERSECTN(DST, SRC1, SRC2, N) \ do { int n = N; \ while (--n >= 0) DST[n] = SRC1[n] & SRC2[n]; \ } while (0) #define UNION(DST, SRC1, SRC2) \ UNIONN (DST, SRC1, SRC2, num_current_words) #define UNIONN(DST, SRC1, SRC2, N) \ do { int n = N; \ while (--n >= 0) DST[n] = SRC1[n] | SRC2[n]; \ } while (0) #define INTERSECT(DST, SRC1, SRC2) \ INTERSECTN (DST, SRC1, SRC2, num_current_words) #define WORD_SIZE ((unsigned int)(sizeof(word) * 8)) static void check_bool_init PARAMS ((tree, words, words, words)); static void check_init PARAMS ((tree, words)); static void check_cond_init PARAMS ((tree, tree, tree, words, words, words)); static void check_bool2_init PARAMS ((enum tree_code, tree, tree, words, words, words)); struct alternatives; static void done_alternative PARAMS ((words, struct alternatives *)); #if 0 #define ALLOC_WORDS(NUM) ((word*) xmalloc ((NUM) * sizeof (word))) #define FREE_WORDS(PTR) (free (PTR)) #else #define ALLOC_WORDS(NUM) ((word*)alloca ((NUM) * sizeof (word))) #define FREE_WORDS(PTR) ((void)0) #endif #define SET_P(WORDS, BIT) \ (WORDS[BIT / WORD_SIZE] & (1 << (BIT % WORD_SIZE))) #define CLEAR_BIT(WORDS, BIT) \ (WORDS[BIT / WORD_SIZE] &= ~ (1 << (BIT % WORD_SIZE))) #define SET_BIT(WORDS, BIT) \ (WORDS[BIT / WORD_SIZE] |= (1 << (BIT % WORD_SIZE))) #define WORDS_NEEDED(BITS) (((BITS)+(WORD_SIZE-1))/(WORD_SIZE)) /* Check a conditional form (TEST_EXP ? THEN_EXP : ELSE_EXP) for definite assignment. BEFORE, WHEN_FALSE, and WHEN_TRUE are as in check_bool_init. */ static void check_cond_init (test_exp, then_exp, else_exp, before, when_false, when_true) tree test_exp, then_exp, else_exp; words before, when_false, when_true; { words tmp = ALLOC_WORDS (6 * num_current_words); words test_false = tmp; words test_true = tmp + num_current_words; words then_false = tmp + 2 * num_current_words; words then_true = tmp + 3 * num_current_words; words else_false = tmp + 4 * num_current_words; words else_true = tmp + 5 * num_current_words; check_bool_init (test_exp, before, test_false, test_true); check_bool_init (then_exp, test_true, then_false, then_true); check_bool_init (else_exp, test_false, else_false, else_true); INTERSECT (when_false, then_false, else_false); INTERSECT (when_true, then_true, else_true); FREE_WORDS (tmp); } /* Check a boolean binary form CODE (EXP0, EXP1), where CODE is one of EQ_EXPR, BIT_AND_EXPR, or BIT_IOR_EXPR. BEFORE, WHEN_FALSE, and WHEN_TRUE are as in check_bool_init. */ static void check_bool2_init (code, exp0, exp1, before, when_false, when_true) enum tree_code code; tree exp0, exp1; words before, when_false, when_true; { word buf[4]; words tmp = num_current_words <= 1 ? buf : ALLOC_WORDS (4 * num_current_words); words when_false_0 = tmp; words when_false_1 = tmp+num_current_words; words when_true_0 = tmp+2*num_current_words; words when_true_1 = tmp+3*num_current_words; check_bool_init (exp0, before, when_false_0, when_true_0); INTERSECT (before, when_false_0, when_true_0); check_bool_init (exp1, before, when_false_1, when_true_1); INTERSECT (before, when_false_1, when_true_1); if (code == EQ_EXPR) { /* Now set: * when_true = (when_false_1 INTERSECTION when_true_1) * UNION (when_true_0 INTERSECTION when_false_1) * UNION (when_false_0 INTERSECTION when_true_1); * using when_false and before as temporary working areas. */ INTERSECT (when_true, when_true_0, when_false_1); INTERSECT (when_false, when_true_0, when_false_1); UNION (when_true, when_true, when_false); UNION (when_true, when_true, before); /* Now set: * when_false = (when_false_1 INTERSECTION when_true_1) * UNION (when_true_0 INTERSECTION when_true_1) * UNION (when_false_0 INTERSECTION when_false_1); * using before as a temporary working area. */ INTERSECT (when_false, when_true_0, when_true_1); UNION (when_false, when_false, before); INTERSECT (before, when_false_0, when_false_1); UNION (when_false, when_false, before); } else if (code == BIT_AND_EXPR || code == TRUTH_AND_EXPR) { UNION (when_true, when_true_0, when_true_1); INTERSECT (when_false, when_false_0, when_false_1); UNION (when_false, when_false, before); } else /* if (code == BIT_IOR_EXPR || code == TRUTH_OR_EXPR) */ { UNION (when_false, when_false_0, when_false_1); INTERSECT (when_true, when_true_0, when_true_1); UNION (when_true, when_true, before); } if (tmp != buf) FREE_WORDS (tmp); } /* Check a boolean expression EXP for definite assignment. BEFORE is the set of variables definitely assigned before the conditional. (This bitstring may be modified arbitrarily in this function.) On output, WHEN_FALSE is the set of variables definitely assigned after the conditional when the conditional is false. On output, WHEN_TRUE is the set of variables definitely assigned after the conditional when the conditional is true. (WHEN_FALSE and WHEN_TRUE are overwritten with initial values ignored.) (None of BEFORE, WHEN_FALSE, or WHEN_TRUE can overlap, as they may be used as temporary working areas. */ static void check_bool_init (exp, before, when_false, when_true) tree exp; words before, when_false, when_true; { switch (TREE_CODE (exp)) { case COND_EXPR: check_cond_init (TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1), TREE_OPERAND (exp, 2), before, when_false, when_true); return; case TRUTH_ANDIF_EXPR: check_cond_init (TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1), boolean_false_node, before, when_false, when_true); return; case TRUTH_ORIF_EXPR: check_cond_init (TREE_OPERAND (exp, 0), boolean_true_node, TREE_OPERAND (exp, 1), before, when_false, when_true); return; case TRUTH_NOT_EXPR: check_bool_init (TREE_OPERAND (exp, 0), before, when_true, when_false); return; case MODIFY_EXPR: { tree tmp = TREE_OPERAND (exp, 0); if (TREE_CODE (tmp) == VAR_DECL && ! FIELD_STATIC (tmp)) { int index; check_bool_init (TREE_OPERAND (exp, 1), before, when_false, when_true); index = DECL_BIT_INDEX (tmp); if (index >= 0) { SET_BIT (when_false, index); SET_BIT (when_true, index); } break; } } goto do_default; case BIT_AND_EXPR: case BIT_IOR_EXPR: case TRUTH_AND_EXPR: case TRUTH_OR_EXPR: case EQ_EXPR: check_bool2_init (TREE_CODE (exp), TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1), before, when_false, when_true); return; case TRUTH_XOR_EXPR: case BIT_XOR_EXPR: case NE_EXPR: /* Just like EQ_EXPR, but switch when_true and when_false. */ check_bool2_init (EQ_EXPR, TREE_OPERAND (exp, 0), TREE_OPERAND (exp, 1), before, when_true, when_false); return; case INTEGER_CST: if (integer_zerop (exp)) { SET_ALL (when_true); COPY (when_false, before); } else { SET_ALL (when_false); COPY (when_true, before); } break; default: do_default: check_init (exp, before); COPY (when_false, before); COPY (when_true, before); } } /* Used to keep track of control flow branches. */ struct alternatives { struct alternatives *outer; /* The value of num_current_locals at the start of this compound. */ int num_locals; /* The value of the "before" set at the start of the control stucture. Used for SWITCH_EXPR but not set for LABELED_BLOCK_EXPR. */ words saved; int save_start_current_locals; /* If num_current_words==1, combined==&one_word, for efficiency. */ word one_word; /* The intersection of the "after" sets from previous branches. */ words combined; tree block; }; struct alternatives * alternatives = NULL; #define BEGIN_ALTERNATIVES(before, current) \ { \ current.saved = NULL; \ current.num_locals = num_current_locals; \ current.combined = num_current_words <= 1 ? ¤t.one_word \ : ALLOC_WORDS (num_current_words); \ SET_ALL (current.combined); \ current.outer = alternatives; \ alternatives = ¤t; \ current.save_start_current_locals = start_current_locals; \ start_current_locals = num_current_locals; \ } static void done_alternative (after, current) words after; struct alternatives *current; { INTERSECTN (current->combined, current->combined, after, WORDS_NEEDED (current->num_locals)); } #define END_ALTERNATIVES(after, current) \ { \ alternatives = current.outer; \ COPY (after, current.combined); \ if (current.combined != ¤t.one_word) \ FREE_WORDS (current.combined); \ start_current_locals = current.save_start_current_locals; \ } /* Check for (un)initialized local variables in EXP. */ static void check_init (exp, before) tree exp; words before; { tree tmp; again: switch (TREE_CODE (exp)) { case VAR_DECL: if (! FIELD_STATIC (exp) && DECL_NAME (exp) != NULL_TREE) { int index = DECL_BIT_INDEX (exp); /* We don't want to report and mark as non initialized flags the are, they will be marked initialized later on when assigned to `true.' */ if ((STATIC_CLASS_INIT_OPT_P () && ! LOCAL_CLASS_INITIALIZATION_FLAG_P (exp)) && index >= 0 && ! SET_P (before, index)) { parse_error_context (wfl, "Variable `%s' may not have been initialized", IDENTIFIER_POINTER (DECL_NAME (exp))); /* Suppress further errors. */ DECL_BIT_INDEX (exp) = -1; } } break; case MODIFY_EXPR: tmp = TREE_OPERAND (exp, 0); /* We're interested in variable declaration and parameter declaration when they're declared with the `final' modifier. */ if ((TREE_CODE (tmp) == VAR_DECL && ! FIELD_STATIC (tmp)) || (TREE_CODE (tmp) == PARM_DECL && LOCAL_FINAL_P (tmp))) { int index; check_init (TREE_OPERAND (exp, 1), before); index = DECL_BIT_INDEX (tmp); /* A final local already assigned or a final parameter assigned must be reported as errors */ if (LOCAL_FINAL_P (tmp) && (index == -1 || TREE_CODE (tmp) == PARM_DECL)) parse_error_context (wfl, "Can't assign here a value to the `final' variable `%s'", IDENTIFIER_POINTER (DECL_NAME (tmp))); if (index >= 0) SET_BIT (before, index); /* Minor optimization. See comment for start_current_locals. If we're optimizing for class initialization, we keep this information to check whether the variable is definitely assigned when once we checked the whole function. */ if (! STATIC_CLASS_INIT_OPT_P () && index >= start_current_locals && index == num_current_locals - 1) { num_current_locals--; DECL_BIT_INDEX (tmp) = -1; } break; } else goto binop; case BLOCK: if (BLOCK_EXPR_BODY (exp)) { tree decl = BLOCK_EXPR_DECLS (exp); int words_needed; word* tmp; int i; int save_start_current_locals = start_current_locals; int save_num_current_words = num_current_words; start_current_locals = num_current_locals; for (; decl != NULL_TREE; decl = TREE_CHAIN (decl)) { DECL_BIT_INDEX (decl) = num_current_locals++; } words_needed = WORDS_NEEDED (num_current_locals); if (words_needed > num_current_words) { tmp = ALLOC_WORDS (words_needed); COPY (tmp, before); num_current_words = words_needed; } else tmp = before; for (i = start_current_locals; i < num_current_locals; i++) CLEAR_BIT (tmp, i); check_init (BLOCK_EXPR_BODY (exp), tmp); num_current_locals = start_current_locals; start_current_locals = save_start_current_locals; if (tmp != before) { num_current_words = save_num_current_words; COPY (before, tmp); FREE_WORDS (tmp); } } break; case LOOP_EXPR: { struct alternatives alt; BEGIN_ALTERNATIVES (before, alt); alt.block = exp; check_init (TREE_OPERAND (exp, 0), before); END_ALTERNATIVES (before, alt); return; } case EXIT_EXPR: { struct alternatives *alt = alternatives; words tmp = ALLOC_WORDS (2 * num_current_words); words when_true = tmp; words when_false = tmp + num_current_words; #ifdef ENABLE_JC1_CHECKING if (TREE_CODE (alt->block) != LOOP_EXPR) abort (); #endif check_bool_init (TREE_OPERAND (exp, 0), before, when_false, when_true); done_alternative (when_true, alt); COPY (before, when_false); FREE_WORDS (tmp); return; } case LABELED_BLOCK_EXPR: { struct alternatives alt; BEGIN_ALTERNATIVES (before, alt); alt.block = exp; if (LABELED_BLOCK_BODY (exp)) check_init (LABELED_BLOCK_BODY (exp), before); done_alternative (before, &alt); END_ALTERNATIVES (before, alt); return; } case EXIT_BLOCK_EXPR: { tree block = TREE_OPERAND (exp, 0); struct alternatives *alt = alternatives; while (alt->block != block) alt = alt->outer; done_alternative (before, alt); SET_ALL (before); return; } case SWITCH_EXPR: { struct alternatives alt; check_init (TREE_OPERAND (exp, 0), before); BEGIN_ALTERNATIVES (before, alt); alt.saved = ALLOC_WORDS (num_current_words); COPY (alt.saved, before); alt.block = exp; check_init (TREE_OPERAND (exp, 1), before); done_alternative (before, &alt); FREE_WORDS (alt.saved); END_ALTERNATIVES (before, alt); return; } case CASE_EXPR: case DEFAULT_EXPR: { int i; struct alternatives *alt = alternatives; while (TREE_CODE (alt->block) != SWITCH_EXPR) alt = alt->outer; COPYN (before, alt->saved, WORDS_NEEDED (alt->num_locals)); for (i = alt->num_locals; i < num_current_locals; i++) CLEAR_BIT (before, i); break; } case CLEANUP_POINT_EXPR: { struct alternatives alt; BEGIN_ALTERNATIVES (before, alt); CLEAR_ALL (alt.combined); check_init (TREE_OPERAND (exp, 0), before); UNION (alt.combined, alt.combined, before); END_ALTERNATIVES (before, alt); } return; case WITH_CLEANUP_EXPR: { struct alternatives *alt = alternatives; #ifdef ENABLE_JC1_CHECKING if (TREE_CODE (alt->block) != CLEANUP_POINT_EXPR) abort (); #endif check_init (TREE_OPERAND (exp, 0), before); UNION (alt->combined, alt->combined, before); check_init (TREE_OPERAND (exp, 1), alt->combined); return; } case TRY_EXPR: { tree try_clause = TREE_OPERAND (exp, 0); tree clause = TREE_OPERAND (exp, 1); words save = ALLOC_WORDS (num_current_words); words tmp = ALLOC_WORDS (num_current_words); struct alternatives alt; BEGIN_ALTERNATIVES (before, alt); COPY (save, before); COPY (tmp, save); check_init (try_clause, tmp); done_alternative (tmp, &alt); for ( ; clause != NULL_TREE; clause = TREE_CHAIN (clause)) { tree catch_clause = TREE_OPERAND (clause, 0); COPY (tmp, save); check_init (catch_clause, tmp); done_alternative (tmp, &alt); } FREE_WORDS (tmp); FREE_WORDS (save); END_ALTERNATIVES (before, alt); } return; case TRY_FINALLY_EXPR: { words tmp = ALLOC_WORDS (num_current_words); COPY (tmp, before); check_init (TREE_OPERAND (exp, 0), before); check_init (TREE_OPERAND (exp, 1), tmp); UNION (before, before, tmp); FREE_WORDS (tmp); } return; case RETURN_EXPR: case THROW_EXPR: if (TREE_OPERAND (exp, 0)) check_init (TREE_OPERAND (exp, 0), before); goto never_continues; case ERROR_MARK: never_continues: SET_ALL (before); return; case COND_EXPR: case TRUTH_ANDIF_EXPR: case TRUTH_ORIF_EXPR: { words tmp = ALLOC_WORDS (2 * num_current_words); words when_true = tmp; words when_false = tmp + num_current_words; check_bool_init (exp, before, when_false, when_true); INTERSECT (before, when_false, when_true); FREE_WORDS (tmp); } break; case UNARY_PLUS_EXPR: case NEGATE_EXPR: case TRUTH_AND_EXPR: case TRUTH_OR_EXPR: case TRUTH_XOR_EXPR: case TRUTH_NOT_EXPR: case BIT_NOT_EXPR: case CONVERT_EXPR: case COMPONENT_REF: case BIT_FIELD_REF: case NOP_EXPR: case FLOAT_EXPR: case FIX_TRUNC_EXPR: case INDIRECT_REF: case ADDR_EXPR: case PREDECREMENT_EXPR: case PREINCREMENT_EXPR: case POSTDECREMENT_EXPR: case POSTINCREMENT_EXPR: case NON_LVALUE_EXPR: case INSTANCEOF_EXPR: case FIX_CEIL_EXPR: case FIX_FLOOR_EXPR: case FIX_ROUND_EXPR: case ABS_EXPR: case FFS_EXPR: /* Avoid needless recursion. */ exp = TREE_OPERAND (exp, 0); goto again; case SAVE_EXPR: if (IS_INIT_CHECKED (exp)) return; IS_INIT_CHECKED (exp) = 1; exp = TREE_OPERAND (exp, 0); goto again; case COMPOUND_EXPR: case PLUS_EXPR: case MINUS_EXPR: case MULT_EXPR: case TRUNC_DIV_EXPR: case TRUNC_MOD_EXPR: case RDIV_EXPR: case LSHIFT_EXPR: case RSHIFT_EXPR: case URSHIFT_EXPR: case BIT_AND_EXPR: case BIT_XOR_EXPR: case BIT_IOR_EXPR: case EQ_EXPR: case NE_EXPR: case GT_EXPR: case GE_EXPR: case LT_EXPR: case LE_EXPR: case MAX_EXPR: case MIN_EXPR: case ARRAY_REF: case LROTATE_EXPR: case RROTATE_EXPR: case CEIL_DIV_EXPR: case FLOOR_DIV_EXPR: case ROUND_DIV_EXPR: case CEIL_MOD_EXPR: case FLOOR_MOD_EXPR: case ROUND_MOD_EXPR: case EXACT_DIV_EXPR: binop: check_init (TREE_OPERAND (exp, 0), before); /* Avoid needless recursion, especially for COMPOUND_EXPR. */ exp = TREE_OPERAND (exp, 1); goto again; case PARM_DECL: case RESULT_DECL: case FUNCTION_DECL: case INTEGER_CST: case REAL_CST: case STRING_CST: case JAVA_EXC_OBJ_EXPR: break; case NEW_CLASS_EXPR: case CALL_EXPR: { tree func = TREE_OPERAND (exp, 0); tree x = TREE_OPERAND (exp, 1); if (TREE_CODE (func) == ADDR_EXPR) func = TREE_OPERAND (func, 0); check_init (func, before); for ( ; x != NULL_TREE; x = TREE_CHAIN (x)) check_init (TREE_VALUE (x), before); if (func == throw_node) goto never_continues; } break; case NEW_ARRAY_INIT: { tree x = CONSTRUCTOR_ELTS (TREE_OPERAND (exp, 0)); for ( ; x != NULL_TREE; x = TREE_CHAIN (x)) check_init (TREE_VALUE (x), before); } break; case EXPR_WITH_FILE_LOCATION: { const char *saved_input_filename = input_filename; tree saved_wfl = wfl; tree body = EXPR_WFL_NODE (exp); int saved_lineno = lineno; if (body == empty_stmt_node) break; wfl = exp; input_filename = EXPR_WFL_FILENAME (exp); lineno = EXPR_WFL_LINENO (exp); check_init (body, before); input_filename = saved_input_filename; lineno = saved_lineno; wfl = saved_wfl; } break; default: internal_error ("internal error in check-init: tree code not implemented: %s", tree_code_name [(int) TREE_CODE (exp)]); } } unsigned int check_for_initialization (body) tree body; { word before = 0; check_init (body, &before); return before; } /* Call for every element in DECL_FUNCTION_INITIALIZED_CLASS_TABLE of a method to consider whether the type indirectly described by ENTRY is definitly initialized and thus remembered as such. */ bool attach_initialized_static_class (entry, ptr) struct hash_entry *entry; PTR ptr; { struct init_test_hash_entry *ite = (struct init_test_hash_entry *) entry; tree fndecl = DECL_CONTEXT (ite->init_test_decl); int index = DECL_BIT_INDEX (ite->init_test_decl); /* If the initializer flag has been definitly assigned (not taking into account its first mandatory assignment which has been already added but escaped analysis.) */ if (fndecl && METHOD_STATIC (fndecl) && (DECL_INITIAL (ite->init_test_decl) == boolean_true_node || (index >= 0 && SET_P (((word *) ptr), index)))) hash_lookup (&DECL_FUNCTION_INITIALIZED_CLASS_TABLE (fndecl), entry->key, TRUE, NULL); return true; }