diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 73 |
1 files changed, 44 insertions, 29 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index cfae846..300d959 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -15487,24 +15487,29 @@ fold_build_pointer_plus_hwi_loc (location_t loc, tree ptr, HOST_WIDE_INT off) ptr, size_int (off)); } -/* Return a pointer P to a NUL-terminated string representing the sequence - of constant characters referred to by SRC (or a subsequence of such - characters within it if SRC is a reference to a string plus some - constant offset). If STRLEN is non-null, store the number of bytes - in the string constant including the terminating NUL char. *STRLEN is - typically strlen(P) + 1 in the absence of embedded NUL characters. */ +/* Return a pointer P to a NUL-terminated string containing the sequence + of bytes corresponding to the representation of the object referred to + by SRC (or a subsequence of such bytes within it if SRC is a reference + to an initialized constant array plus some constant offset). + If STRSIZE is non-null, store the number of bytes in the constant + sequence including the terminating NUL byte. *STRSIZE is equal to + sizeof(A) - OFFSET where A is the array that stores the constant + sequence that SRC points to and OFFSET is the byte offset of SRC from + the beginning of A. SRC need not point to a string or even an array + of characters but may point to an object of any type. */ const char * -c_getstr (tree src, unsigned HOST_WIDE_INT *strlen /* = NULL */) +c_getstr (tree src, unsigned HOST_WIDE_INT *strsize /* = NULL */) { + /* The offset into the array A storing the string, and A's byte size. */ tree offset_node; tree mem_size; - if (strlen) - *strlen = 0; + if (strsize) + *strsize = 0; src = string_constant (src, &offset_node, &mem_size, NULL); - if (src == 0) + if (!src) return NULL; unsigned HOST_WIDE_INT offset = 0; @@ -15519,34 +15524,44 @@ c_getstr (tree src, unsigned HOST_WIDE_INT *strlen /* = NULL */) if (!tree_fits_uhwi_p (mem_size)) return NULL; - /* STRING_LENGTH is the size of the string literal, including any - embedded NULs. STRING_SIZE is the size of the array the string - literal is stored in. */ - unsigned HOST_WIDE_INT string_length = TREE_STRING_LENGTH (src); - unsigned HOST_WIDE_INT string_size = tree_to_uhwi (mem_size); + /* ARRAY_SIZE is the byte size of the array the constant sequence + is stored in and equal to sizeof A. INIT_BYTES is the number + of bytes in the constant sequence used to initialize the array, + including any embedded NULs as well as the terminating NUL (for + strings), but not including any trailing zeros/NULs past + the terminating one appended implicitly to a string literal to + zero out the remainder of the array it's stored in. For example, + given: + const char a[7] = "abc\0d"; + n = strlen (a + 1); + ARRAY_SIZE is 7, INIT_BYTES is 6, and OFFSET is 1. For a valid + (i.e., nul-terminated) string with no embedded nuls, INIT_BYTES + is equal to strlen (A) + 1. */ + const unsigned HOST_WIDE_INT array_size = tree_to_uhwi (mem_size); + unsigned HOST_WIDE_INT init_bytes = TREE_STRING_LENGTH (src); /* Ideally this would turn into a gcc_checking_assert over time. */ - if (string_length > string_size) - string_length = string_size; + if (init_bytes > array_size) + init_bytes = array_size; const char *string = TREE_STRING_POINTER (src); /* Ideally this would turn into a gcc_checking_assert over time. */ - if (string_length > string_size) - string_length = string_size; + if (init_bytes > array_size) + init_bytes = array_size; - if (string_length == 0 - || offset >= string_size) + if (init_bytes == 0 || offset >= array_size) return NULL; - if (strlen) + if (strsize) { - /* Compute and store the length of the substring at OFFSET. - All offsets past the initial length refer to null strings. */ - if (offset < string_length) - *strlen = string_length - offset; + /* Compute and store the number of characters from the beginning + of the substring at OFFSET to the end, including the terminating + nul. Offsets past the initial length refer to null strings. */ + if (offset < init_bytes) + *strsize = init_bytes - offset; else - *strlen = 1; + *strsize = 1; } else { @@ -15554,11 +15569,11 @@ c_getstr (tree src, unsigned HOST_WIDE_INT *strlen /* = NULL */) /* Support only properly NUL-terminated single byte strings. */ if (tree_to_uhwi (TYPE_SIZE_UNIT (eltype)) != 1) return NULL; - if (string[string_length - 1] != '\0') + if (string[init_bytes - 1] != '\0') return NULL; } - return offset < string_length ? string + offset : ""; + return offset < init_bytes ? string + offset : ""; } /* Given a tree T, compute which bits in T may be nonzero. */ |