Re: [Mingw-users] MSYS build of m4 version > 1.4.15

[Earnie B. <ea...@us...>]

On Thu, Feb 21, 2013 at 6:05 PM, Erwin Waterlander wrote:
> Greg Chicares schreef, Op 21-2-2013 23:15:
>> On 2013-02-20 22:06Z, Erwin Waterlander wrote:
>> [...]
>>> Configure hangs forever during this step:
>>>
>>> checking whether strstr works in linear time...
>> According to this report, it can take several minutes:
>>
>> http://sourceware.org/ml/libc-alpha/2012-06/msg00772.html
>> | > user    4m21.060s
>> |
>> | Yes, if an strstr implementation takes more than 4 minutes to search for
>> | a 100000 byte long string in a 2000000 byte long string, it's quadratic
>> | behaviour.
>>
>> That message also shows the source code, which contains this comment:
>>
>> | > |     /* Failure to compile this test due to missing alarm is okay,
>> | > |        since all such platforms (mingw) also have quadratic strstr.  */
>> | > |     signal (SIGALRM, quit);
>>
>> The "mingw" comment wouldn't apply to MSYS, but perhaps MSYS's version
>> of newlib has a strstr() that performs poorly on this test.
>>
>> You may wish to experiment with lower values of 'm' here:
>>
>> | > |     size_t m = 1000000;
>> | > |     char *haystack = (char *) malloc (2 * m + 2);
>> | > |     char *needle = (char *) malloc (m + 2);
>>
>> If it works quickly with m=1000, and is noticeably slow with m=100000,
>> then you could extrapolate how long m=1000000 would take...in order to
>> guess whether the problem lies here, or elsewhere. I'm not set up to
>> compile for MSYS, or I'd do it myself, sorry.
>>
>
> Hi Greg,
>
> You solved the problem. The check was already running for three and a
> half hours on my 2 year old desktop. By changing m to 1000 the test
> finished in a second on my 6 year old laptop. Thanks!

I remember the issue now.  I thought this had been taken care of with
updates to autoconf itself.  I must be wrong.

-- 
Earnie
-- https://sites.google.com/site/earnieboyd