diff options
Diffstat (limited to 'gcc/tree-ssa-strlen.c')
| -rw-r--r-- | gcc/tree-ssa-strlen.c | 194 |
1 files changed, 117 insertions, 77 deletions
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c index 4af4785..ef2b6ae 100644 --- a/gcc/tree-ssa-strlen.c +++ b/gcc/tree-ssa-strlen.c @@ -1195,14 +1195,13 @@ adjust_last_stmt (strinfo *si, gimple *stmt, bool is_strcat) to constants. */ tree -set_strlen_range (tree lhs, wide_int max, tree bound /* = NULL_TREE */) +set_strlen_range (tree lhs, wide_int min, wide_int max, + tree bound /* = NULL_TREE */) { if (TREE_CODE (lhs) != SSA_NAME || !INTEGRAL_TYPE_P (TREE_TYPE (lhs))) return NULL_TREE; - wide_int min = wi::zero (max.get_precision ()); - if (bound) { /* For strnlen, adjust MIN and MAX as necessary. If the bound @@ -1312,7 +1311,8 @@ maybe_set_strlen_range (tree lhs, tree src, tree bound) } } - return set_strlen_range (lhs, max, bound); + wide_int min = wi::zero (max.get_precision ()); + return set_strlen_range (lhs, min, max, bound); } /* Handle a strlen call. If strlen of the argument is known, replace @@ -1434,6 +1434,12 @@ handle_builtin_strlen (gimple_stmt_iterator *gsi) tree adj = fold_build2_loc (loc, MINUS_EXPR, TREE_TYPE (lhs), lhs, old); adjust_related_strinfos (loc, si, adj); + /* Use the constant minimim length as the lower bound + of the non-constant length. */ + wide_int min = wi::to_wide (old); + wide_int max + = wi::to_wide (TYPE_MAX_VALUE (ptrdiff_type_node)) - 2; + set_strlen_range (lhs, min, max); } else { @@ -3386,9 +3392,51 @@ int ssa_name_limit_t::next_ssa_name (tree ssa_name) on success and false otherwise. */ static bool -count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, +count_nonzero_bytes (tree exp, unsigned HOST_WIDE_INT offset, + unsigned HOST_WIDE_INT nbytes, + unsigned lenrange[3], bool *nulterm, bool *allnul, bool *allnonnul, ssa_name_limit_t &snlim) { + int idx = get_stridx (exp); + if (idx > 0) + { + strinfo *si = get_strinfo (idx); + /* FIXME: Handle non-constant lengths in some range. */ + if (!si || !tree_fits_shwi_p (si->nonzero_chars)) + return false; + + unsigned len = tree_to_shwi (si->nonzero_chars); + unsigned size = len + si->full_string_p; + if (size <= offset) + return false; + + len -= offset; + size -= offset; + + if (size < nbytes) + return false; + + if (len < lenrange[0]) + lenrange[0] = len; + if (lenrange[1] < len) + lenrange[1] = len; + + if (!si->full_string_p) + *nulterm = false; + + /* Since only the length of the string are known and + its contents, clear ALLNUL and ALLNONNUL purely on + the basis of the length. */ + if (len) + *allnul = false; + else + *allnonnul = false; + return true; + } + + if (TREE_CODE (exp) == ADDR_EXPR) + exp = TREE_OPERAND (exp, 0); + if (TREE_CODE (exp) == SSA_NAME) { /* Handle a single-character specially. */ @@ -3401,7 +3449,8 @@ count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, (even if its exact value is not known) and if so, recurse once to set the range, etc. */ if (tree_expr_nonzero_p (exp)) - return count_nonzero_bytes (build_int_cst (type, 1), lenrange, + return count_nonzero_bytes (build_int_cst (type, 1), + offset, nbytes, lenrange, nulterm, allnul, allnonnul, snlim); /* Don't know whether EXP is or isn't nonzero. */ return false; @@ -3422,35 +3471,28 @@ count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, for (unsigned i = 0; i != n; i++) { tree def = gimple_phi_arg_def (stmt, i); - if (!count_nonzero_bytes (def, lenrange, nulterm, allnul, allnonnul, - snlim)) + if (!count_nonzero_bytes (def, offset, nbytes, lenrange, nulterm, + allnul, allnonnul, snlim)) return false; } return true; } - /* Offset from the beginning of the representation bytes, a pointer - to the representation, and the number of bytes of the representation - to consider (may be less than the object size for MEM_REF). */ - unsigned HOST_WIDE_INT offset = 0; - const char *prep = NULL; - unsigned nbytes = 0; - if (TREE_CODE (exp) == MEM_REF) { - /* If the MEM_REF operand is the address of an object such as - a string or integer, extract it and the offset into it. */ tree arg = TREE_OPERAND (exp, 0); - if (TREE_CODE (arg) != ADDR_EXPR) - return false; - tree off = TREE_OPERAND (exp, 1); + if (TREE_CODE (off) != INTEGER_CST || !tree_fits_uhwi_p (off)) return false; - offset = tree_to_uhwi (off); + unsigned HOST_WIDE_INT wioff = tree_to_uhwi (off); + if (INT_MAX < wioff) + return false; + + offset += wioff; if (INT_MAX < offset) return false; @@ -3458,38 +3500,12 @@ count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, tree type = TREE_TYPE (exp); if (tree typesize = TYPE_SIZE_UNIT (type)) nbytes = tree_to_uhwi (typesize); + else + return false; - if (offset == 0 && TREE_CODE (exp) != STRING_CST) - { - int idx = get_stridx (arg); - if (idx > 0) - { - strinfo *si = get_strinfo (idx); - if (si && tree_fits_shwi_p (si->nonzero_chars)) - { - unsigned len = tree_to_shwi (si->nonzero_chars); - if (len < lenrange[0]) - lenrange[0] = len; - if (lenrange[1] < len) - lenrange[1] = len; - - if (!si->full_string_p) - *nulterm = false; - - /* Since only the length of the string are known and - its contents, clear ALLNUL and ALLNONNUL purely on - the basis of the length. */ - if (len) - *allnul = false; - else - *allnonnul = false; - return true; - } - } - } - - /* Proceed to extract the object representation below. */ - exp = TREE_OPERAND (arg, 0); + /* Handle MEM_REF = SSA_NAME types of assignments. */ + return count_nonzero_bytes (arg, offset, nbytes, lenrange, nulterm, + allnul, allnonnul, snlim); } if (TREE_CODE (exp) == VAR_DECL && TREE_READONLY (exp)) @@ -3499,20 +3515,18 @@ count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, return false; } + const char *prep = NULL; if (TREE_CODE (exp) == STRING_CST) { - /* Set PREP and NBYTES to the string representation. */ - gcc_assert (offset <= INT_MAX); + unsigned nchars = TREE_STRING_LENGTH (exp); + if (nchars < offset) + return false; if (!nbytes) - { - /* Unless NBYTES has already been determined above from - MEM_REF, set it here. It includes all internal nuls, - including the terminating one if the string has one. */ - nbytes = TREE_STRING_LENGTH (exp); - if (nbytes <= offset) - return false; - } + /* If NBYTES hasn't been determined earlier from MEM_REF, + set it here. It includes all internal nuls, including + the terminating one if the string has one. */ + nbytes = nchars - offset; prep = TREE_STRING_POINTER (exp) + offset; } @@ -3520,12 +3534,14 @@ count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, unsigned char buf[256]; if (!prep) { - /* Try to extract the representation of the constant object. */ - nbytes = native_encode_expr (exp, buf, sizeof buf, -1); + /* If the pointer to representation hasn't been set above + for STRING_CST point it at the buffer. */ + prep = reinterpret_cast <char *>(buf); + /* Try to extract the representation of the constant object + or expression starting from the offset. */ + nbytes = native_encode_expr (exp, buf, sizeof buf, offset); if (!nbytes) return false; - - prep = reinterpret_cast <char *>(buf); } /* Compute the number of leading nonzero bytes in the representation @@ -3591,7 +3607,8 @@ count_nonzero_bytes (tree exp, unsigned lenrange[3], bool *nulterm, *allnonnul = true; ssa_name_limit_t snlim; - return count_nonzero_bytes (exp, lenrange, nulterm, allnul, allnonnul, snlim); + return count_nonzero_bytes (exp, 0, 0, lenrange, nulterm, allnul, allnonnul, + snlim); } /* Handle a single or multibyte store other than by a built-in function, @@ -3664,11 +3681,14 @@ handle_store (gimple_stmt_iterator *gsi) if (tree dstsize = compute_objsize (lhs, 1)) if (compare_tree_int (dstsize, lenrange[2]) < 0) - warning_n (gimple_location (stmt), OPT_Wstringop_overflow_, - lenrange[2], - "%Gwriting %u byte into a region of size %E", - "%Gwriting %u bytes into a region of size %E", - stmt, lenrange[2], dstsize); + { + location_t loc = gimple_nonartificial_location (stmt); + warning_n (loc, OPT_Wstringop_overflow_, + lenrange[2], + "%Gwriting %u byte into a region of size %E", + "%Gwriting %u bytes into a region of size %E", + stmt, lenrange[2], dstsize); + } } else { @@ -3795,7 +3815,14 @@ handle_store (gimple_stmt_iterator *gsi) } else si->nonzero_chars = build_int_cst (size_type_node, offset); - si->full_string_p = full_string_p; + + /* Set FULL_STRING_P only if the length of the strings being + written is the same, and clear it if the strings have + different lengths. In the latter case the length stored + in si->NONZERO_CHARS becomes the lower bound. + FIXME: Handle the upper bound of the length if possible. */ + si->full_string_p = full_string_p && lenrange[0] == lenrange[1]; + if (storing_all_zeros_p && ssaname && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (ssaname)) @@ -3825,10 +3852,23 @@ handle_store (gimple_stmt_iterator *gsi) if (idx != 0) { tree ptr = (ssaname ? ssaname : build_fold_addr_expr (lhs)); - HOST_WIDE_INT slen = (storing_all_zeros_p - ? 0 - : (storing_nonzero_p - && ranges_valid ? lenrange[0] : -1)); + + HOST_WIDE_INT slen; + if (storing_all_zeros_p) + slen = 0; + else if (storing_nonzero_p && ranges_valid) + { + /* FIXME: Handle the upper bound of the length when + LENRANGE[0] != LENRANGE[1]. */ + slen = lenrange[0]; + if (lenrange[0] != lenrange[1]) + /* Set the minimum length but ignore the maximum + for now. */ + full_string_p = false; + } + else + slen = -1; + tree len = (slen <= 0 ? size_zero_node : build_int_cst (size_type_node, slen)); |