| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Victor Wagner <vitus(at)wagner(dot)pp(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Bug fix for glibc broke freebsd build in REL_11_STABLE |
| Date: | 2018-09-04 21:46:29 |
| Message-ID: | 2481.1536097589@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
> The reason it behaves oddly is this: on i387 FPU (and NOT on arm32 or on
> 32-bit i386 with a modern architecture specified to the compiler), the
> result of 1e200 * 1e180 is not in fact infinite, because it fits in an
> 80-bit long double. So __builtin_isinf reports that it is finite; but if
> it gets stored to memory as a double (e.g. to pass as a parameter to a
> function), it then becomes infinite.
Ah-hah. Can we fix it by explicitly casting the argument of isinf
to double?
regards, tom lane
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