Reporting bugs: there is nothing to gain in frustrating reporters
Mattias Karlsson
betasoft@acc.umu.se
Sat Jun 18 13:52:00 GMT 2005
On Sat, 18 Jun 2005, Robert Dewar wrote:
> Mattias Karlsson wrote:
>> On Sat, 18 Jun 2005, Robert Dewar wrote:
>>
>>> Mattias Karlsson wrote:
>>>
>>>> Don't know about you, but I consider any processor that is unable to
>>>> store a register to memory and then read back the same value to be buggy.
>>>
>>>
>>> THe x86/x87 does not violate this requirement
>
>> In my Obi-Wan-Point-Of-View it does. :-)
>
> Well I think it is inapprorpiate to assign erroneous points of
> view to Obi-Wan :-) Once again, on the x86/x87 the process IS "able
> to store a register to memory and then read back the same value".
> ANy claim to the contrary is ill-informed.
>
>> This entire debate comes from one thing: currently floating point has
>> always type long double untill stored to memory, regardless of
>> user-specified type. At -O1 this becomes more or less non-deterministic.
>
> Yes, right, but that is a different issue from being able to store
> a register to memory and then read back the same value.
I confess of being overly generic, and quite fuzzy about my point.
Anyway my point of view is that the solution to anyone needing strict IEEE
semantics are:
1) Use -float-store
2) Use sse math
3) Learn to live without it.
Since the "gcc-is-buggy" solution of changing x87 rounding modes will:
1) Be a lot of work.
2) Cause a lot of regressions.
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