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/* __builtin_object_size (ptr, object_size_type) computation Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc. Contributed by Jakub Jelinek <jakub@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 "diagnostic.h" #include "tree-flow.h" #include "tree-pass.h" #include "tree-ssa-propagate.h" struct object_size_info { int object_size_type; bitmap visited, reexamine; int pass; bool changed; unsigned int *depths; unsigned int *stack, *tos; }; static unsigned HOST_WIDE_INT unknown[4] = { -1, -1, 0, 0 }; static tree compute_object_offset (tree, tree); static unsigned HOST_WIDE_INT addr_object_size (tree, int); static unsigned HOST_WIDE_INT alloc_object_size (tree, int); static tree pass_through_call (tree); static void collect_object_sizes_for (struct object_size_info *, tree); static void expr_object_size (struct object_size_info *, tree, tree); static bool merge_object_sizes (struct object_size_info *, tree, tree, unsigned HOST_WIDE_INT); static bool plus_expr_object_size (struct object_size_info *, tree, tree); static unsigned int compute_object_sizes (void); static void init_offset_limit (void); static void check_for_plus_in_loops (struct object_size_info *, tree); static void check_for_plus_in_loops_1 (struct object_size_info *, tree, unsigned int); /* object_sizes[0] is upper bound for number of bytes till the end of the object. object_sizes[1] is upper bound for number of bytes till the end of the subobject (innermost array or field with address taken). object_sizes[2] is lower bound for number of bytes till the end of the object and object_sizes[3] lower bound for subobject. */ static unsigned HOST_WIDE_INT *object_sizes[4]; /* Bitmaps what object sizes have been computed already. */ static bitmap computed[4]; /* Maximum value of offset we consider to be addition. */ static unsigned HOST_WIDE_INT offset_limit; /* Initialize OFFSET_LIMIT variable. */ static void init_offset_limit (void) { if (host_integerp (TYPE_MAX_VALUE (sizetype), 1)) offset_limit = tree_low_cst (TYPE_MAX_VALUE (sizetype), 1); else offset_limit = -1; offset_limit /= 2; } /* Compute offset of EXPR within VAR. Return error_mark_node if unknown. */ static tree compute_object_offset (tree expr, tree var) { enum tree_code code = PLUS_EXPR; tree base, off, t; if (expr == var) return size_zero_node; switch (TREE_CODE (expr)) { case COMPONENT_REF: base = compute_object_offset (TREE_OPERAND (expr, 0), var); if (base == error_mark_node) return base; t = TREE_OPERAND (expr, 1); off = size_binop (PLUS_EXPR, DECL_FIELD_OFFSET (t), size_int (tree_low_cst (DECL_FIELD_BIT_OFFSET (t), 1) / BITS_PER_UNIT)); break; case REALPART_EXPR: case NOP_EXPR: case CONVERT_EXPR: case VIEW_CONVERT_EXPR: case NON_LVALUE_EXPR: return compute_object_offset (TREE_OPERAND (expr, 0), var); case IMAGPART_EXPR: base = compute_object_offset (TREE_OPERAND (expr, 0), var); if (base == error_mark_node) return base; off = TYPE_SIZE_UNIT (TREE_TYPE (expr)); break; case ARRAY_REF: base = compute_object_offset (TREE_OPERAND (expr, 0), var); if (base == error_mark_node) return base; t = TREE_OPERAND (expr, 1); if (TREE_CODE (t) == INTEGER_CST && tree_int_cst_sgn (t) < 0) { code = MINUS_EXPR; t = fold_build1 (NEGATE_EXPR, TREE_TYPE (t), t); } t = fold_convert (sizetype, t); off = size_binop (MULT_EXPR, TYPE_SIZE_UNIT (TREE_TYPE (expr)), t); break; default: return error_mark_node; } return size_binop (code, base, off); } /* Compute __builtin_object_size for PTR, which is a ADDR_EXPR. OBJECT_SIZE_TYPE is the second argument from __builtin_object_size. If unknown, return unknown[object_size_type]. */ static unsigned HOST_WIDE_INT addr_object_size (tree ptr, int object_size_type) { tree pt_var; gcc_assert (TREE_CODE (ptr) == ADDR_EXPR); pt_var = TREE_OPERAND (ptr, 0); if (REFERENCE_CLASS_P (pt_var)) pt_var = get_base_address (pt_var); if (pt_var && (SSA_VAR_P (pt_var) || TREE_CODE (pt_var) == STRING_CST) && TYPE_SIZE_UNIT (TREE_TYPE (pt_var)) && host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (pt_var)), 1) && (unsigned HOST_WIDE_INT) tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (pt_var)), 1) < offset_limit) { tree bytes; if (pt_var != TREE_OPERAND (ptr, 0)) { tree var; if (object_size_type & 1) { var = TREE_OPERAND (ptr, 0); while (var != pt_var && TREE_CODE (var) != BIT_FIELD_REF && TREE_CODE (var) != COMPONENT_REF && TREE_CODE (var) != ARRAY_REF && TREE_CODE (var) != ARRAY_RANGE_REF && TREE_CODE (var) != REALPART_EXPR && TREE_CODE (var) != IMAGPART_EXPR) var = TREE_OPERAND (var, 0); if (var != pt_var && TREE_CODE (var) == ARRAY_REF) var = TREE_OPERAND (var, 0); if (! TYPE_SIZE_UNIT (TREE_TYPE (var)) || ! host_integerp (TYPE_SIZE_UNIT (TREE_TYPE (var)), 1) || tree_int_cst_lt (TYPE_SIZE_UNIT (TREE_TYPE (pt_var)), TYPE_SIZE_UNIT (TREE_TYPE (var)))) var = pt_var; } else var = pt_var; bytes = compute_object_offset (TREE_OPERAND (ptr, 0), var); if (bytes != error_mark_node) { if (TREE_CODE (bytes) == INTEGER_CST && tree_int_cst_lt (TYPE_SIZE_UNIT (TREE_TYPE (var)), bytes)) bytes = size_zero_node; else bytes = size_binop (MINUS_EXPR, TYPE_SIZE_UNIT (TREE_TYPE (var)), bytes); } } else bytes = TYPE_SIZE_UNIT (TREE_TYPE (pt_var)); if (host_integerp (bytes, 1)) return tree_low_cst (bytes, 1); } return unknown[object_size_type]; } /* Compute __builtin_object_size for CALL, which is a CALL_EXPR. Handles various allocation calls. OBJECT_SIZE_TYPE is the second argument from __builtin_object_size. If unknown, return unknown[object_size_type]. */ static unsigned HOST_WIDE_INT alloc_object_size (tree call, int object_size_type) { tree callee, arglist, a, bytes = NULL_TREE; unsigned int arg_mask = 0; gcc_assert (TREE_CODE (call) == CALL_EXPR); callee = get_callee_fndecl (call); arglist = TREE_OPERAND (call, 1); if (callee && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) switch (DECL_FUNCTION_CODE (callee)) { case BUILT_IN_MALLOC: case BUILT_IN_ALLOCA: arg_mask = 1; break; /* case BUILT_IN_REALLOC: arg_mask = 2; break; */ case BUILT_IN_CALLOC: arg_mask = 3; break; default: break; } for (a = arglist; arg_mask && a; arg_mask >>= 1, a = TREE_CHAIN (a)) if (arg_mask & 1) { tree arg = TREE_VALUE (a); if (TREE_CODE (arg) != INTEGER_CST) break; if (! bytes) bytes = fold_convert (sizetype, arg); else bytes = size_binop (MULT_EXPR, bytes, fold_convert (sizetype, arg)); } if (! arg_mask && bytes && host_integerp (bytes, 1)) return tree_low_cst (bytes, 1); return unknown[object_size_type]; } /* If object size is propagated from one of function's arguments directly to its return value, return that argument for CALL_EXPR CALL. Otherwise return NULL. */ static tree pass_through_call (tree call) { tree callee = get_callee_fndecl (call); tree arglist = TREE_OPERAND (call, 1); if (callee && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) switch (DECL_FUNCTION_CODE (callee)) { case BUILT_IN_MEMCPY: case BUILT_IN_MEMMOVE: case BUILT_IN_MEMSET: case BUILT_IN_STRCPY: case BUILT_IN_STRNCPY: case BUILT_IN_STRCAT: case BUILT_IN_STRNCAT: case BUILT_IN_MEMCPY_CHK: case BUILT_IN_MEMMOVE_CHK: case BUILT_IN_MEMSET_CHK: case BUILT_IN_STRCPY_CHK: case BUILT_IN_STRNCPY_CHK: case BUILT_IN_STRCAT_CHK: case BUILT_IN_STRNCAT_CHK: if (arglist) return TREE_VALUE (arglist); break; default: break; } return NULL_TREE; } /* Compute __builtin_object_size value for PTR. OBJECT_SIZE_TYPE is the second argument from __builtin_object_size. */ unsigned HOST_WIDE_INT compute_builtin_object_size (tree ptr, int object_size_type) { gcc_assert (object_size_type >= 0 && object_size_type <= 3); if (! offset_limit) init_offset_limit (); if (TREE_CODE (ptr) == ADDR_EXPR) return addr_object_size (ptr, object_size_type); else if (TREE_CODE (ptr) == CALL_EXPR) { tree arg = pass_through_call (ptr); if (arg) return compute_builtin_object_size (arg, object_size_type); else return alloc_object_size (ptr, object_size_type); } else if (TREE_CODE (ptr) == SSA_NAME && POINTER_TYPE_P (TREE_TYPE (ptr)) && object_sizes[object_size_type] != NULL) { if (!bitmap_bit_p (computed[object_size_type], SSA_NAME_VERSION (ptr))) { struct object_size_info osi; bitmap_iterator bi; unsigned int i; if (dump_file) { fprintf (dump_file, "Computing %s %sobject size for ", (object_size_type & 2) ? "minimum" : "maximum", (object_size_type & 1) ? "sub" : ""); print_generic_expr (dump_file, ptr, dump_flags); fprintf (dump_file, ":\n"); } osi.visited = BITMAP_ALLOC (NULL); osi.reexamine = BITMAP_ALLOC (NULL); osi.object_size_type = object_size_type; osi.depths = NULL; osi.stack = NULL; osi.tos = NULL; /* First pass: walk UD chains, compute object sizes that can be computed. osi.reexamine bitmap at the end will contain what variables were found in dependency cycles and therefore need to be reexamined. */ osi.pass = 0; osi.changed = false; collect_object_sizes_for (&osi, ptr); /* Second pass: keep recomputing object sizes of variables that need reexamination, until no object sizes are increased or all object sizes are computed. */ if (! bitmap_empty_p (osi.reexamine)) { bitmap reexamine = BITMAP_ALLOC (NULL); /* If looking for minimum instead of maximum object size, detect cases where a pointer is increased in a loop. Although even without this detection pass 2 would eventually terminate, it could take a long time. If a pointer is increasing this way, we need to assume 0 object size. E.g. p = &buf[0]; while (cond) p = p + 4; */ if (object_size_type & 2) { osi.depths = XCNEWVEC (unsigned int, num_ssa_names); osi.stack = XNEWVEC (unsigned int, num_ssa_names); osi.tos = osi.stack; osi.pass = 1; /* collect_object_sizes_for is changing osi.reexamine bitmap, so iterate over a copy. */ bitmap_copy (reexamine, osi.reexamine); EXECUTE_IF_SET_IN_BITMAP (reexamine, 0, i, bi) if (bitmap_bit_p (osi.reexamine, i)) check_for_plus_in_loops (&osi, ssa_name (i)); free (osi.depths); osi.depths = NULL; free (osi.stack); osi.stack = NULL; osi.tos = NULL; } do { osi.pass = 2; osi.changed = false; /* collect_object_sizes_for is changing osi.reexamine bitmap, so iterate over a copy. */ bitmap_copy (reexamine, osi.reexamine); EXECUTE_IF_SET_IN_BITMAP (reexamine, 0, i, bi) if (bitmap_bit_p (osi.reexamine, i)) { collect_object_sizes_for (&osi, ssa_name (i)); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Reexamining "); print_generic_expr (dump_file, ssa_name (i), dump_flags); fprintf (dump_file, "\n"); } } } while (osi.changed); BITMAP_FREE (reexamine); } EXECUTE_IF_SET_IN_BITMAP (osi.reexamine, 0, i, bi) bitmap_set_bit (computed[object_size_type], i); /* Debugging dumps. */ if (dump_file) { EXECUTE_IF_SET_IN_BITMAP (osi.visited, 0, i, bi) if (object_sizes[object_size_type][i] != unknown[object_size_type]) { print_generic_expr (dump_file, ssa_name (i), dump_flags); fprintf (dump_file, ": %s %sobject size " HOST_WIDE_INT_PRINT_UNSIGNED "\n", (object_size_type & 2) ? "minimum" : "maximum", (object_size_type & 1) ? "sub" : "", object_sizes[object_size_type][i]); } } BITMAP_FREE (osi.reexamine); BITMAP_FREE (osi.visited); } return object_sizes[object_size_type][SSA_NAME_VERSION (ptr)]; } return unknown[object_size_type]; } /* Compute object_sizes for PTR, defined to VALUE, which is not a SSA_NAME. */ static void expr_object_size (struct object_size_info *osi, tree ptr, tree value) { int object_size_type = osi->object_size_type; unsigned int varno = SSA_NAME_VERSION (ptr); unsigned HOST_WIDE_INT bytes; gcc_assert (object_sizes[object_size_type][varno] != unknown[object_size_type]); gcc_assert (osi->pass == 0); if (TREE_CODE (value) == WITH_SIZE_EXPR) value = TREE_OPERAND (value, 0); /* Pointer variables should have been handled by merge_object_sizes. */ gcc_assert (TREE_CODE (value) != SSA_NAME || !POINTER_TYPE_P (TREE_TYPE (value))); if (TREE_CODE (value) == ADDR_EXPR) bytes = addr_object_size (value, object_size_type); else if (TREE_CODE (value) == CALL_EXPR) bytes = alloc_object_size (value, object_size_type); else bytes = unknown[object_size_type]; if ((object_size_type & 2) == 0) { if (object_sizes[object_size_type][varno] < bytes) object_sizes[object_size_type][varno] = bytes; } else { if (object_sizes[object_size_type][varno] > bytes) object_sizes[object_size_type][varno] = bytes; } } /* Merge object sizes of ORIG + OFFSET into DEST. Return true if the object size might need reexamination later. */ static bool merge_object_sizes (struct object_size_info *osi, tree dest, tree orig, unsigned HOST_WIDE_INT offset) { int object_size_type = osi->object_size_type; unsigned int varno = SSA_NAME_VERSION (dest); unsigned HOST_WIDE_INT orig_bytes; if (object_sizes[object_size_type][varno] == unknown[object_size_type]) return false; if (offset >= offset_limit) { object_sizes[object_size_type][varno] = unknown[object_size_type]; return false; } if (osi->pass == 0) collect_object_sizes_for (osi, orig); orig_bytes = object_sizes[object_size_type][SSA_NAME_VERSION (orig)]; if (orig_bytes != unknown[object_size_type]) orig_bytes = (offset > orig_bytes) ? (unsigned HOST_WIDE_INT) 0 : orig_bytes - offset; if ((object_size_type & 2) == 0) { if (object_sizes[object_size_type][varno] < orig_bytes) { object_sizes[object_size_type][varno] = orig_bytes; osi->changed = true; } } else { if (object_sizes[object_size_type][varno] > orig_bytes) { object_sizes[object_size_type][varno] = orig_bytes; osi->changed = true; } } return bitmap_bit_p (osi->reexamine, SSA_NAME_VERSION (orig)); } /* Compute object_sizes for PTR, defined to VALUE, which is a PLUS_EXPR. Return true if the object size might need reexamination later. */ static bool plus_expr_object_size (struct object_size_info *osi, tree var, tree value) { tree op0 = TREE_OPERAND (value, 0); tree op1 = TREE_OPERAND (value, 1); bool ptr1_p = POINTER_TYPE_P (TREE_TYPE (op0)) && TREE_CODE (op0) != INTEGER_CST; bool ptr2_p = POINTER_TYPE_P (TREE_TYPE (op1)) && TREE_CODE (op1) != INTEGER_CST; int object_size_type = osi->object_size_type; unsigned int varno = SSA_NAME_VERSION (var); unsigned HOST_WIDE_INT bytes; gcc_assert (TREE_CODE (value) == PLUS_EXPR); if (object_sizes[object_size_type][varno] == unknown[object_size_type]) return false; /* Swap operands if needed. */ if (ptr2_p && !ptr1_p) { tree tem = op0; op0 = op1; op1 = tem; ptr1_p = true; ptr2_p = false; } /* Handle PTR + OFFSET here. */ if (ptr1_p && !ptr2_p && TREE_CODE (op1) == INTEGER_CST && (TREE_CODE (op0) == SSA_NAME || TREE_CODE (op0) == ADDR_EXPR)) { if (! host_integerp (op1, 1)) bytes = unknown[object_size_type]; else if (TREE_CODE (op0) == SSA_NAME) return merge_object_sizes (osi, var, op0, tree_low_cst (op1, 1)); else { unsigned HOST_WIDE_INT off = tree_low_cst (op1, 1); bytes = compute_builtin_object_size (op0, object_size_type); if (off > offset_limit) bytes = unknown[object_size_type]; else if (off > bytes) bytes = 0; else bytes -= off; } } else bytes = unknown[object_size_type]; if ((object_size_type & 2) == 0) { if (object_sizes[object_size_type][varno] < bytes) object_sizes[object_size_type][varno] = bytes; } else { if (object_sizes[object_size_type][varno] > bytes) object_sizes[object_size_type][varno] = bytes; } return false; } /* Compute object sizes for VAR. For ADDR_EXPR an object size is the number of remaining bytes to the end of the object (where what is considered an object depends on OSI->object_size_type). For allocation CALL_EXPR like malloc or calloc object size is the size of the allocation. For pointer PLUS_EXPR where second operand is a constant integer, object size is object size of the first operand minus the constant. If the constant is bigger than the number of remaining bytes until the end of the object, object size is 0, but if it is instead a pointer subtraction, object size is unknown[object_size_type]. To differentiate addition from subtraction, ADDR_EXPR returns unknown[object_size_type] for all objects bigger than half of the address space, and constants less than half of the address space are considered addition, while bigger constants subtraction. For a memcpy like CALL_EXPR that always returns one of its arguments, the object size is object size of that argument. Otherwise, object size is the maximum of object sizes of variables that it might be set to. */ static void collect_object_sizes_for (struct object_size_info *osi, tree var) { int object_size_type = osi->object_size_type; unsigned int varno = SSA_NAME_VERSION (var); tree stmt; bool reexamine; if (bitmap_bit_p (computed[object_size_type], varno)) return; if (osi->pass == 0) { if (! bitmap_bit_p (osi->visited, varno)) { bitmap_set_bit (osi->visited, varno); object_sizes[object_size_type][varno] = (object_size_type & 2) ? -1 : 0; } else { /* Found a dependency loop. Mark the variable for later re-examination. */ bitmap_set_bit (osi->reexamine, varno); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Found a dependency loop at "); print_generic_expr (dump_file, var, dump_flags); fprintf (dump_file, "\n"); } return; } } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Visiting use-def links for "); print_generic_expr (dump_file, var, dump_flags); fprintf (dump_file, "\n"); } stmt = SSA_NAME_DEF_STMT (var); reexamine = false; switch (TREE_CODE (stmt)) { case RETURN_EXPR: gcc_assert (TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR); stmt = TREE_OPERAND (stmt, 0); /* FALLTHRU */ case MODIFY_EXPR: { tree rhs = TREE_OPERAND (stmt, 1), arg; STRIP_NOPS (rhs); if (TREE_CODE (rhs) == CALL_EXPR) { arg = pass_through_call (rhs); if (arg) rhs = arg; } if (TREE_CODE (rhs) == SSA_NAME && POINTER_TYPE_P (TREE_TYPE (rhs))) reexamine = merge_object_sizes (osi, var, rhs, 0); else if (TREE_CODE (rhs) == PLUS_EXPR) reexamine = plus_expr_object_size (osi, var, rhs); else expr_object_size (osi, var, rhs); break; } case ASM_EXPR: /* Pointers defined by __asm__ statements can point anywhere. */ object_sizes[object_size_type][varno] = unknown[object_size_type]; break; case NOP_EXPR: { tree decl = SSA_NAME_VAR (var); gcc_assert (IS_EMPTY_STMT (stmt)); if (TREE_CODE (decl) != PARM_DECL && DECL_INITIAL (decl)) expr_object_size (osi, var, DECL_INITIAL (decl)); else expr_object_size (osi, var, decl); } break; case PHI_NODE: { int i; for (i = 0; i < PHI_NUM_ARGS (stmt); i++) { tree rhs = PHI_ARG_DEF (stmt, i); if (object_sizes[object_size_type][varno] == unknown[object_size_type]) break; if (TREE_CODE (rhs) == SSA_NAME) reexamine |= merge_object_sizes (osi, var, rhs, 0); else if (osi->pass == 0) expr_object_size (osi, var, rhs); } break; } default: gcc_unreachable (); } if (! reexamine || object_sizes[object_size_type][varno] == unknown[object_size_type]) { bitmap_set_bit (computed[object_size_type], varno); bitmap_clear_bit (osi->reexamine, varno); } else { bitmap_set_bit (osi->reexamine, varno); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Need to reexamine "); print_generic_expr (dump_file, var, dump_flags); fprintf (dump_file, "\n"); } } } /* Helper function for check_for_plus_in_loops. Called recursively to detect loops. */ static void check_for_plus_in_loops_1 (struct object_size_info *osi, tree var, unsigned int depth) { tree stmt = SSA_NAME_DEF_STMT (var); unsigned int varno = SSA_NAME_VERSION (var); if (osi->depths[varno]) { if (osi->depths[varno] != depth) { unsigned int *sp; /* Found a loop involving pointer addition. */ for (sp = osi->tos; sp > osi->stack; ) { --sp; bitmap_clear_bit (osi->reexamine, *sp); bitmap_set_bit (computed[osi->object_size_type], *sp); object_sizes[osi->object_size_type][*sp] = 0; if (*sp == varno) break; } } return; } else if (! bitmap_bit_p (osi->reexamine, varno)) return; osi->depths[varno] = depth; *osi->tos++ = varno; switch (TREE_CODE (stmt)) { case RETURN_EXPR: gcc_assert (TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR); stmt = TREE_OPERAND (stmt, 0); /* FALLTHRU */ case MODIFY_EXPR: { tree rhs = TREE_OPERAND (stmt, 1), arg; STRIP_NOPS (rhs); if (TREE_CODE (rhs) == CALL_EXPR) { arg = pass_through_call (rhs); if (arg) rhs = arg; } if (TREE_CODE (rhs) == SSA_NAME) check_for_plus_in_loops_1 (osi, rhs, depth); else if (TREE_CODE (rhs) == PLUS_EXPR) { tree op0 = TREE_OPERAND (rhs, 0); tree op1 = TREE_OPERAND (rhs, 1); tree cst, basevar; if (TREE_CODE (op0) == SSA_NAME) { basevar = op0; cst = op1; } else { basevar = op1; cst = op0; gcc_assert (TREE_CODE (basevar) == SSA_NAME); } gcc_assert (TREE_CODE (cst) == INTEGER_CST); check_for_plus_in_loops_1 (osi, basevar, depth + !integer_zerop (cst)); } else gcc_unreachable (); break; } case PHI_NODE: { int i; for (i = 0; i < PHI_NUM_ARGS (stmt); i++) { tree rhs = PHI_ARG_DEF (stmt, i); if (TREE_CODE (rhs) == SSA_NAME) check_for_plus_in_loops_1 (osi, rhs, depth); } break; } default: gcc_unreachable (); } osi->depths[varno] = 0; osi->tos--; } /* Check if some pointer we are computing object size of is being increased within a loop. If yes, assume all the SSA variables participating in that loop have minimum object sizes 0. */ static void check_for_plus_in_loops (struct object_size_info *osi, tree var) { tree stmt = SSA_NAME_DEF_STMT (var); switch (TREE_CODE (stmt)) { case RETURN_EXPR: gcc_assert (TREE_CODE (TREE_OPERAND (stmt, 0)) == MODIFY_EXPR); stmt = TREE_OPERAND (stmt, 0); /* FALLTHRU */ case MODIFY_EXPR: { tree rhs = TREE_OPERAND (stmt, 1), arg; STRIP_NOPS (rhs); if (TREE_CODE (rhs) == CALL_EXPR) { arg = pass_through_call (rhs); if (arg) rhs = arg; } if (TREE_CODE (rhs) == PLUS_EXPR) { tree op0 = TREE_OPERAND (rhs, 0); tree op1 = TREE_OPERAND (rhs, 1); tree cst, basevar; if (TREE_CODE (op0) == SSA_NAME) { basevar = op0; cst = op1; } else { basevar = op1; cst = op0; gcc_assert (TREE_CODE (basevar) == SSA_NAME); } gcc_assert (TREE_CODE (cst) == INTEGER_CST); if (integer_zerop (cst)) break; osi->depths[SSA_NAME_VERSION (basevar)] = 1; *osi->tos++ = SSA_NAME_VERSION (basevar); check_for_plus_in_loops_1 (osi, var, 2); osi->depths[SSA_NAME_VERSION (basevar)] = 0; osi->tos--; } break; } default: break; } } /* Initialize data structures for the object size computation. */ void init_object_sizes (void) { int object_size_type; if (object_sizes[0]) return; for (object_size_type = 0; object_size_type <= 3; object_size_type++) { object_sizes[object_size_type] = XNEWVEC (unsigned HOST_WIDE_INT, num_ssa_names); computed[object_size_type] = BITMAP_ALLOC (NULL); } init_offset_limit (); } /* Destroy data structures after the object size computation. */ void fini_object_sizes (void) { int object_size_type; for (object_size_type = 0; object_size_type <= 3; object_size_type++) { free (object_sizes[object_size_type]); BITMAP_FREE (computed[object_size_type]); object_sizes[object_size_type] = NULL; } } /* Simple pass to optimize all __builtin_object_size () builtins. */ static unsigned int compute_object_sizes (void) { basic_block bb; FOR_EACH_BB (bb) { block_stmt_iterator i; for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) { tree *stmtp = bsi_stmt_ptr (i); tree call = get_rhs (*stmtp); tree callee, result; if (!call || TREE_CODE (call) != CALL_EXPR) continue; callee = get_callee_fndecl (call); if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL || DECL_FUNCTION_CODE (callee) != BUILT_IN_OBJECT_SIZE) continue; init_object_sizes (); result = fold_builtin (callee, TREE_OPERAND (call, 1), false); if (!result) { tree arglist = TREE_OPERAND (call, 1); if (arglist != NULL && POINTER_TYPE_P (TREE_TYPE (TREE_VALUE (arglist))) && TREE_CHAIN (arglist) != NULL && TREE_CHAIN (TREE_CHAIN (arglist)) == NULL) { tree ost = TREE_VALUE (TREE_CHAIN (arglist)); if (host_integerp (ost, 1)) { unsigned HOST_WIDE_INT object_size_type = tree_low_cst (ost, 1); if (object_size_type < 2) result = fold_convert (size_type_node, integer_minus_one_node); else if (object_size_type < 4) result = size_zero_node; } } if (!result) continue; } if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "Simplified\n "); print_generic_stmt (dump_file, *stmtp, dump_flags); } if (!set_rhs (stmtp, result)) gcc_unreachable (); update_stmt (*stmtp); if (dump_file && (dump_flags & TDF_DETAILS)) { fprintf (dump_file, "to\n "); print_generic_stmt (dump_file, *stmtp, dump_flags); fprintf (dump_file, "\n"); } } } fini_object_sizes (); return 0; } struct tree_opt_pass pass_object_sizes = { "objsz", /* name */ NULL, /* gate */ compute_object_sizes, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ 0, /* tv_id */ PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */ 0 /* letter */ };
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