On Thu, Jun 06, 2019 at 01:32:14PM -0600, Martin Sebor wrote:
> Hi Jeff,
>
> It looks like the updated comment for get_range_strlen didn't make
> it into the strlen fixup commits last December and the function
> still has the old description. (Not surprising given there are
> at least two overloads of the same function and things moving
> between them.) I'm going to check in the comment from the patch
> here: https://gcc.gnu.org/ml/gcc-patches/2018-11/msg02050.html
> with an additional sentence describing ELTSIZE.
>
> Let me know if you'd like me to tweak it or if spot something
> else.
>
> Thanks
> Martin
> gcc/ChangeLog:
>
> * gimple-fold.c (get_range_strlen): Update comment that didn't
> make it into r267503 or related commits.
>
> diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
> index b3e931744f8..18860bb7c28 100644
> --- a/gcc/gimple-fold.c
> +++ b/gcc/gimple-fold.c
> @@ -1672,30 +1672,16 @@ get_range_strlen (tree arg, bitmap *visited,
> }
> }
>
> -/* Determine the minimum and maximum value or string length that ARG
> - refers to and store each in the first two elements of MINMAXLEN.
> - For expressions that point to strings of unknown lengths that are
> - character arrays, use the upper bound of the array as the maximum
> - length. For example, given an expression like 'x ? array : "xyz"'
> - and array declared as 'char array[8]', MINMAXLEN[0] will be set
> - to 0 and MINMAXLEN[1] to 7, the longest string that could be
> - stored in array.
> - Return true if the range of the string lengths has been obtained
> - from the upper bound of an array at the end of a struct. Such
> - an array may hold a string that's longer than its upper bound
> - due to it being used as a poor-man's flexible array member.
> -
> - STRICT is true if it will handle PHIs and COND_EXPRs conservatively
> - and false if PHIs and COND_EXPRs are to be handled optimistically,
> - if we can determine string length minimum and maximum; it will use
> - the minimum from the ones where it can be determined.
> - STRICT false should be only used for warning code.
> - When non-null, clear *NONSTR if ARG refers to a constant array
> - that is known not be nul-terminated. Otherwise set it to
> - the declaration of the constant non-terminated array.
> -
> - ELTSIZE is 1 for normal single byte character strings, and 2 or
> - 4 for wide characer strings. ELTSIZE is by default 1. */
> +/* Try to obtain the range of the lengths of the string(s) referenced
> + by ARG, or the size of the largest array ARG refers to if the range
> + of lengths cannot be determined, and store all in *PDATA. ELTSIZE
> + is the expected size of the string element in bytes: 1 for char and
> + some power of 2 for wide characters.
> + Return true if the range [PDATA->MINLEN, PDATA->MAXLEN] is suitable
> + for optimization. Returning false means that a nonzero PDATA->MINLEN
> + doesn't reflect the true lower bound of the range when PDATA->MAXLEN
^^
There are two spaces instead of one. No need to repost just because of
this, of course.
Marek
