From: Stefan Liebler <stli@linux.vnet.ibm.com>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH] string/stratcliff.c: Replace int with size_t [BZ #21982]
Date: Mon, 21 Aug 2017 13:49:00 -0000 [thread overview]
Message-ID: <25604b34-7afb-7007-4ea8-3add9963d4b4@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170820171713.GA19531@gmail.com>
On 08/20/2017 07:17 PM, H.J. Lu wrote:
> Fix GCC 7 errors when string/stratcliff.c is compiled with -O3:
>
> stratcliff.c: In function âdo_testâ:
> cc1: error: assuming signed overflow does not occur when assuming that (X - c) <= X is always true [-Werror=strict-overflow]
>
> OK for master?
>
> H.J.
> ---
> [BZ #21982]
> * string/stratcliff.c (do_test): Declare size, nchars, inner,
> middle and outer with size_t instead of int. Repleace %d with
> %Zd in printf.
> ---
> string/stratcliff.c | 72 ++++++++++++++++++++++++++---------------------------
> 1 file changed, 36 insertions(+), 36 deletions(-)
>
> diff --git a/string/stratcliff.c b/string/stratcliff.c
> index e28b0c5058..ae780379cb 100644
> --- a/string/stratcliff.c
> +++ b/string/stratcliff.c
> @@ -58,8 +58,8 @@
> int
> do_test (void)
> {
> - int size = sysconf (_SC_PAGESIZE);
> - int nchars = size / sizeof (CHAR);
> + size_t size = sysconf (_SC_PAGESIZE);
> + size_t nchars = size / sizeof (CHAR);
> CHAR *adr;
> CHAR *dest;
> int result = 0;
> @@ -80,7 +80,7 @@ do_test (void)
> }
> else
> {
> - int inner, middle, outer;
> + size_t inner, middle, outer;
>
> mprotect (adr, size, PROT_NONE);
> mprotect (adr + 2 * nchars, size, PROT_NONE);
> @@ -101,7 +101,7 @@ do_test (void)
>
> if (STRLEN (&adr[outer]) != (size_t) (inner - outer))
> {
> - printf ("%s flunked for outer = %d, inner = %d\n",
> + printf ("%s flunked for outer = %Zd, inner = %Zd\n",
> STRINGIFY (STRLEN), outer, inner);
> result = 1;
> }
> {
> - printf ("%s flunked for outer = %d, middle = %d\n",
> + printf ("%s flunked for outer = %Zd, middle = %Zd\n",
> STRINGIFY (rawmemchr), outer, middle);
> result = 1;
> }
> Hi H.J. Lu,
I've applied your patch and the warnings does not occur anymore on s390.
The outer loops of the string tests are all using the following:
size_t nchars, outer;
for (outer = nchars - 1; outer >= MAX (0, nchars - 128); --outer)
I think we can assume, that nchars is always > 128 as it is derived by
the pagesize.
But if nchars would be equal to 128, this would result in an infinite
loop (outer >= 0)?
If nchars would be less than 128, the tests would be skipped.
Should we add a check that nchars > 128 at the beginning and replace the
"MAX (0, nchars - 128)" with only "nchars - 128"?
Bye,
Stefan
next prev parent reply other threads:[~2017-08-21 13:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-20 17:17 H.J. Lu
2017-08-21 13:25 ` Joseph Myers
2017-08-21 13:51 ` H.J. Lu
2017-08-21 13:56 ` Joseph Myers
2017-08-21 15:03 ` H.J. Lu
2017-08-21 13:49 ` Stefan Liebler [this message]
2017-08-21 14:53 ` H.J. Lu
2017-08-21 15:41 ` Stefan Liebler
2017-08-21 23:05 ` H.J. Lu
2017-08-22 12:07 ` Stefan Liebler
2017-08-22 12:43 ` H.J. Lu
2017-08-22 14:57 ` Stefan Liebler
2017-08-23 14:49 ` H.J. Lu
2017-09-07 16:20 ` H.J. Lu
2017-09-11 15:46 ` H.J. Lu
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