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[Bug target/37390] wrong-code on i486-linux-gnu with -O[12], -O0 works




------- Comment #7 from niklaus at gmail dot com  2008-09-06 18:28 -------

(In reply to comment #5)
> Subject: Re:  wrong-code on i486-linux-gnu with -O[12], -O0 works
> 
> Because on x86 gnu/Linux, the precision is set to 80bits rather than  
> 64bit like it is on windows.
> >

Does increasing bits cause floating point errors. How could 64 bit precison
give correct result where as 80 bit give incorrect one.

 I mean with changing the pow to powl and double to long double fixes the issue
with optimization. Isn't long double precision 80 bits ?


Also 1 more question .

junk@edubuntu:~/prog/tju$ gcc -O2 -mfpmath=sse bug_short.c -lm
bug_short.c:1: warning: SSE instruction set disabled, using 387 arithmetics

Shouldn't this be SSE instruction enabled and 387 disabled. 387 is causing the
problem right ? 
I could be wrong , thats what i could figure out from the mail thread you
marked as duplicate.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37390

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