diff options
Diffstat (limited to 'gcc/builtins.c')
| -rw-r--r-- | gcc/builtins.c | 63 |
1 files changed, 35 insertions, 28 deletions
diff --git a/gcc/builtins.c b/gcc/builtins.c index 6716aab..b1a79f3 100644 --- a/gcc/builtins.c +++ b/gcc/builtins.c @@ -568,41 +568,43 @@ string_length (const void *ptr, unsigned eltsize, unsigned maxelts) accesses. Note that this implies the result is not going to be emitted into the instruction stream. - The value returned is of type `ssizetype'. + ELTSIZE is 1 for normal single byte character strings, and 2 or + 4 for wide characer strings. ELTSIZE is by default 1. - Unfortunately, string_constant can't access the values of const char - arrays with initializers, so neither can we do so here. */ + The value returned is of type `ssizetype'. */ tree -c_strlen (tree src, int only_value) +c_strlen (tree src, int only_value, unsigned eltsize) { + gcc_assert (eltsize == 1 || eltsize == 2 || eltsize == 4); STRIP_NOPS (src); if (TREE_CODE (src) == COND_EXPR && (only_value || !TREE_SIDE_EFFECTS (TREE_OPERAND (src, 0)))) { tree len1, len2; - len1 = c_strlen (TREE_OPERAND (src, 1), only_value); - len2 = c_strlen (TREE_OPERAND (src, 2), only_value); + len1 = c_strlen (TREE_OPERAND (src, 1), only_value, eltsize); + len2 = c_strlen (TREE_OPERAND (src, 2), only_value, eltsize); if (tree_int_cst_equal (len1, len2)) return len1; } if (TREE_CODE (src) == COMPOUND_EXPR && (only_value || !TREE_SIDE_EFFECTS (TREE_OPERAND (src, 0)))) - return c_strlen (TREE_OPERAND (src, 1), only_value); + return c_strlen (TREE_OPERAND (src, 1), only_value, eltsize); location_t loc = EXPR_LOC_OR_LOC (src, input_location); /* Offset from the beginning of the string in bytes. */ tree byteoff; - src = string_constant (src, &byteoff); + tree memsize; + src = string_constant (src, &byteoff, &memsize); if (src == 0) return NULL_TREE; /* Determine the size of the string element. */ - unsigned eltsize - = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (src)))); + if (eltsize != tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (src))))) + return NULL_TREE; /* Set MAXELTS to sizeof (SRC) / sizeof (*SRC) - 1, the maximum possible length of SRC. Prefer TYPE_SIZE() to TREE_STRING_LENGTH() if possible @@ -613,14 +615,10 @@ c_strlen (tree src, int only_value) HOST_WIDE_INT strelts = TREE_STRING_LENGTH (src); strelts = strelts / eltsize - 1; - HOST_WIDE_INT maxelts = strelts; - tree type = TREE_TYPE (src); - if (tree size = TYPE_SIZE_UNIT (type)) - if (tree_fits_shwi_p (size)) - { - maxelts = tree_to_uhwi (size); - maxelts = maxelts / eltsize - 1; - } + if (!tree_fits_uhwi_p (memsize)) + return NULL_TREE; + + HOST_WIDE_INT maxelts = tree_to_uhwi (memsize) / eltsize - 1; /* PTR can point to the byte representation of any string type, including char* and wchar_t*. */ @@ -628,19 +626,23 @@ c_strlen (tree src, int only_value) if (byteoff && TREE_CODE (byteoff) != INTEGER_CST) { + /* For empty strings the result should be zero. */ + if (maxelts == 0) + return ssize_int (0); + + /* The code below works only for single byte character types. */ + if (eltsize != 1) + return NULL_TREE; + /* If the string has an internal NUL character followed by any non-NUL characters (e.g., "foo\0bar"), we can't compute the offset to the following NUL if we don't know where to start searching for it. */ unsigned len = string_length (ptr, eltsize, strelts); - if (len < strelts) - { - /* Return when an embedded null character is found. */ - return NULL_TREE; - } - if (!maxelts) - return ssize_int (0); + /* Return when an embedded null character is found or none at all. */ + if (len < strelts || len > maxelts) + return NULL_TREE; /* We don't know the starting offset, but we do know that the string has no internal zero bytes. If the offset falls within the bounds @@ -650,8 +652,8 @@ c_strlen (tree src, int only_value) tree offsave = TREE_SIDE_EFFECTS (byteoff) ? save_expr (byteoff) : byteoff; offsave = fold_convert (ssizetype, offsave); tree condexp = fold_build2_loc (loc, LE_EXPR, boolean_type_node, offsave, - build_int_cst (ssizetype, len * eltsize)); - tree lenexp = size_diffop_loc (loc, ssize_int (strelts * eltsize), offsave); + build_int_cst (ssizetype, len)); + tree lenexp = size_diffop_loc (loc, ssize_int (strelts), offsave); return fold_build3_loc (loc, COND_EXPR, ssizetype, condexp, lenexp, build_zero_cst (ssizetype)); } @@ -684,6 +686,11 @@ c_strlen (tree src, int only_value) return NULL_TREE; } + /* If eltoff is larger than strelts but less than maxelts the + string length is zero, since the excess memory will be zero. */ + if (eltoff > strelts) + return ssize_int (0); + /* Use strlen to search for the first zero byte. Since any strings constructed with build_string will have nulls appended, we win even if we get handed something like (char[4])"abcd". @@ -691,7 +698,7 @@ c_strlen (tree src, int only_value) Since ELTOFF is our starting index into the string, no further calculation is needed. */ unsigned len = string_length (ptr + eltoff * eltsize, eltsize, - maxelts - eltoff); + strelts - eltoff); return ssize_int (len); } |