[Bug optimization/323] optimized code gives strange floating point results

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gccbug at chiefrocker dot
                   |                            |net


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-01 18:36 -------
*** Bug 11394 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |deshpand at cs dot umn dot
                   |                            |edu


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-01 18:39 -------
*** Bug 629 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bart dot vanassche at yucom
                   |                            |dot be


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-01 18:45 -------
*** Bug 4251 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |36876 at bugs dot debian dot
                   |                            |org


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-01 18:46 -------
*** Bug 6900 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |csk at cgl dot uwaterloo dot
                   |                            |ca


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-01 18:46 -------
*** Bug 10417 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |INVALID


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-05 00:07 -------
Invalid and so that bugzilla can pick up it for the dup count.

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|CLOSED                      |REOPENED
         Resolution|FIXED                       |


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-05 00:06 -------
Reopening so I can mark it as ...

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bird at bainet dot com


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-06 19:11 -------
*** Bug 10644 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jmurray at dsrnet dot com


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-06 19:16 -------
*** Bug 2582 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |166255 at bugs dot debian
                   |                            |dot org


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-06 19:20 -------
*** Bug 8606 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |have at ann dot jussieu dot
                   |                            |fr


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-10 11:35 -------
*** Bug 6824 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gsinai at yudit dot org


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-14 12:45 -------
*** Bug 11518 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gtalbot at locuspharma dot
                   |                            |com


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-07-21 17:28 -------
*** Bug 11618 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nick at ilm dot com


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-24 02:40 -------
*** Bug 11655 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lothar at xcerla dot com


------- Additional Comments From pinskia at physics dot uc dot edu  2003-08-03 14:14 -------
*** Bug 11767 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323



------- Additional Comments From pinskia at physics dot uc dot edu  2003-08-04 18:18 -------
*** Bug 11767 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simon dot marshall at misys
                   |                            |dot com


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-08-12 12:51 -------
*** Bug 11892 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[ehrhardt at mathematik dot uni-ulm dot de]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


ehrhardt at mathematik dot uni-ulm dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |birger dot b at gmx dot net


------- Additional Comments From ehrhardt at mathematik dot uni-ulm dot de  2003-08-14 07:28 -------
*** Bug 11914 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kevin at moore-and-moore dot
                   |                            |com


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-08-15 20:24 -------
*** Bug 11934 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |preciseflight at yahoo dot
                   |                            |com dot au


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-09-02 13:34 -------
*** Bug 12129 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |adam at irvine dot com


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-09-18 18:36 -------
*** Bug 12331 has been marked as a duplicate of this bug. ***

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-12-01 22:47 -------
*** Bug 13265 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |muks at mukund dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-01-27 22:51 -------
*** Bug 13890 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |paul_blankenbaker at yahoo
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-01 17:28 -------
*** Bug 14367 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |djerius at cfa dot harvard
                   |                            |dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-03 19:18 -------
*** Bug 14384 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anz at obs-nice dot fr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-11 05:48 -------
*** Bug 14384 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-03-19 15:41 -------
*** Bug 14652 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |olcios at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-04-17 05:29 -------
*** Bug 14989 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |wxy at kivera dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-04-25 16:55 -------
*** Bug 15134 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |laurent at guerby dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-14 16:54 -------
*** Bug 15437 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lani at oas dot ca


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-06-06 18:13 -------
*** Bug 15852 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sliwa at theta1 dot cft dot
                   |                            |edu dot pl


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-06-27 19:46 -------
*** Bug 16223 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc-erikd at mega-nerd dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-17 17:40 -------
*** Bug 16607 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |npr1 at suomi24 dot fi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-17 22:29 -------
*** Bug 16607 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-19 01:19 -------
*** Bug 15386 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |diego at biurrun dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[zack at gcc dot gnu dot org]

------- Additional Comments From zack at gcc dot gnu dot org  2004-07-19 03:22 -------
*** Bug 16607 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-23 09:21 -------
*** Bug 16686 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bernert at planet dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-10-03 14:54 -------
*** Bug 17802 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jonathan at csse dot uwa dot
                   |                            |edu dot au


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[sliwa at cft dot edu dot pl]

------- Additional Comments From sliwa at cft dot edu dot pl  2004-10-03 15:52 -------
Excessive precision should be discarded before performing any comparison. It is
done e.g. by the Intel fortran compiler. -ffloat-store rounds only the values
stored in a variable, and in some situations may trigger instead of suppressing
the bug. Existing numerical software packages (e.g. LAPACK and SLATEC fortran
libraries) fail their tests with gcc just due to this issue.
So it is a bug, even if almost all other compilers reproduce it.
If you refer me to a FAQ on numerical analysis, please note that the FAQ states
things as they are, and not as they should be.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[jonathan at csse dot uwa dot edu dot au]

------- Additional Comments From jonathan at csse dot uwa dot edu dot au  2004-10-04 10:57 -------
Some musings based on my encounter with this bug...

Comparison of doubles is not just restricted to numerical analysis.  Bug report
17802 (aka #323) arose out of a binary search of a timer queue.  Is it wrong to
assume that if "int secs = 2" and "int usecs = 100000" then "secs + 1e-6 *
usecs" will return the same result every time it is evaluated as an inline function?

Calling a trivial function twice with an identical parameter may return a value
less than, equal to or greater than itself (depending on register allocation in
the context of the calls).  This is a really nasty piece of nondeterministic
behaviour.  Weren't compilers and "high level" languages invented to get around
exactly this kind of hardware dependency?

Compiling with -ffloat-store did not help in my case.  Compiling without -O
isn't always possible either.  Since the function that causes the problem is the
trivial calculation above, inlined for performance, I can't guarrantee that
every user of the header file it appears in will know to compile without -O (or
be willing to).  The outcome will be users reporting a bug in my code.

This bug is being reported regularly, and probably affecting a lot more people
that don't report it.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-19 15:32 -------
*** Bug 18567 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |benoit dot sibaud at rd dot
                   |                            |francetelecom dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-19 15:33 -------
*** Bug 18567 has been marked as a duplicate of this bug. ***
------- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-01 15:12 -------
*** Bug 18756 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |eda-qa at disemia dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[eda-qa at disemia dot com]

------- Additional Comments From eda-qa at disemia dot com  2004-12-01 16:24 -------
To summarize, this defect effectively states that:

assert( (x/y) == (x/y) )

may cause an assertion if compiled with optimization.

While I understand why it happens, that doesn't mean it isn't a defect.  This
makes it impossible to turn on the optimizer with any code using floating point
and still expect to get a correct result.  Perhaps in some situations this is
okay, but in general this is not.

This would also mean the following are also invalid code -- which I'm fairly
certain the C/C++ standards would state otherwise:

a = (x/y);
assert( a == x/y ) //may Abort

if( a == x/y )
  assert( a == x/y )  //may Abort

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-02 14:22 -------
*** Bug 18784 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Graham dot Murphy at jhuapl
                   |                            |dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-15 14:05 -------
*** Bug 19011 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |konstantin at mysql dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-12-15 15:10 -------
*** Bug 19011 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-17 15:40 -------
*** Bug 19469 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |debian-gcc at lists dot
                   |                            |debian dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-28 18:47 -------
*** Bug 19675 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cognot at earthdecision dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-28 19:07 -------
*** Bug 19675 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-09 06:35 -------
*** Bug 19837 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |wirawan0 at softhome dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-17 13:37 -------
*** Bug 20026 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |denis dot nagorny at intel
                   |                            |dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-28 21:53 -------
*** Bug 20674 has been marked as a duplicate of this bug. ***

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           What    |Removed                     |Added
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                 CC|                            |piaget at us dot ibm dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-29 14:17 -------
*** Bug 20674 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-20 03:00 -------
*** Bug 7719 has been marked as a duplicate of this bug. ***

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           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |petr dot savicky at cuni dot
                   |                            |cz


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[mario dot tragni at planetek dot it]

------- Additional Comments From mario dot tragni at planetek dot it  2005-05-20 08:40 -------
(In reply to comment #2)
> State-Changed-From-To: open->closed
> State-Changed-Why: See any faq on numerical analysis that mentions the x86.
>     You are seeing the results of excess precision in the FPU.
>     Either change the rounding precision in the FPCR, or work
>     around the problem with -ffloat-store.
> 

I had this bug on x86 architecture, with no optimization of the code (no -OX)
and with float-store on. My workaround was to store the return of the double
function in a auxliar double variable before comparison.
Have you an other suggestion ?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[cognot at earthdecision dot com]

------- Additional Comments From cognot at earthdecision dot com  2005-05-20 10:03 -------
(In reply to comment #59)
> 
> I had this bug on x86 architecture, with no optimization of the code (no -OX)
> and with float-store on. My workaround was to store the return of the double
> function in a auxliar double variable before comparison.
> Have you an other suggestion ?
> 

The way I've "fixed" (more like avoided) this problem is to have:

#include <fpu_control.h>

void set_math_double_precision() {
  fpu_control_t fpu_control = 0x027f ;
  _FPU_SETCW(fpu_control);
}

and make sure this function is called before doing any FP operations. It only
needs to be called once.

Richard.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 16:24 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |themis_hv at yahoo dot co
                   |                            |dot uk


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 18:27 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 19:06 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 19:24 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 19:35 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 19:43 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 19:47 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-29 19:56 -------
*** Bug 21809 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-06-19 11:05 -------
Reopening...

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           What    |Removed                     |Added
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             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-06-19 11:09 -------
...to end this pointless discussion.

Some people call this a bug in the x87 series.  Other call it a bug in
gcc.  See these mails at least for the reason why this could be considered
a bug in gcc: 
http://gcc.gnu.org/ml/gcc/2003-08/msg01195.html
http://gcc.gnu.org/ml/gcc/2003-08/msg01234.html
http://gcc.gnu.org/ml/gcc/2003-08/msg01257.html

Regardless of where one wishes to put the blame, this problem will _not_ be
fixed.  Period.



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           What    |Removed                     |Added
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             Status|REOPENED                    |SUSPENDED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-19 12:18 -------
*** Bug 1098 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |green at rhythm dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-10 18:09 -------
*** Bug 22394 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |glenn at aoi-industries dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-09 15:59 -------
*** Bug 23298 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dsell at agleader dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-15 21:23 -------
*** Bug 23407 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dir at lanl dot gov


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-16 13:22 -------
*** Bug 23318 has been marked as a duplicate of this bug. ***

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323

[Bug rtl-optimization/323] optimized code gives strange floating point results

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-22 15:48 -------
*** Bug 24014 has been marked as a duplicate of this bug. ***

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           What    |Removed                     |Added
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                 CC|                            |u dot strempel at gmx dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323