>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> 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.
Tom> Ah-hah. Can we fix it by explicitly casting the argument of isinf
Tom> to double?
No; the generated code doesn't change. Presumably the compiler regards
the value as already being of type "double", just one that happens to be
stored in a longer register.
--
Andrew (irc:RhodiumToad)