Re: BUG #15519: Casting float4 into int4 gets the wrong sign instead of "integer out of range" error - Mailing list pgsql-bugs

From Andrew Gierth
Subject Re: BUG #15519: Casting float4 into int4 gets the wrong sign instead of "integer out of range" error
Date
Msg-id 87va4nqr1a.fsf@news-spur.riddles.org.uk
Whole thread Raw
In response to Re: BUG #15519: Casting float4 into int4 gets the wrong sign instead of "integer out of range" error  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: BUG #15519: Casting float4 into int4 gets the wrong sign insteadof "integer out of range" error  (Victor Petrovykh <victor@magic.io>)
List pgsql-bugs
>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:

 Tom> if (unlikely(num < (float4) INT_MIN || num >= (float4) INT_MAX || isnan(num)))

 >> if (num < (float4)INT_MIN || num >= -(float4)INT_MIN || ...

 Tom> Meh. Seems to me that's relying on pretty much the same
 Tom> assumptions

No, because we know that INT_MIN is always exactly representable as a
float (whereas INT_MAX is not), and therefore the cast result will not
depend on any rounding choices whether at compile or run time. Nor does
it depend on knowing that float4 can't represent INT_MAX exactly.

-- 
Andrew (irc:RhodiumToad)


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