Hello, > This 'little' program behaves bad when compiled with -O. It works fine > when no -O or -O0 is used. > > The function is from Graphics Gem I and has been ported from C to C++ > http://www.acm.org/pubs/tog/GraphicsGems/gems.html#gems > Woo, Andrew, Fast Ray-Box Intersection, p. 395-396, code: p. 736-737 > > This is how things went when compiling on my Debian unstable (current as > of 2006-06-18). > The problem has also been encountererd on redhat rhel (3?) but not > investigated there. > > No flags were used except -On (The program do compile cleanly with > -Wall -W -pedantic) > > > -O0 -O1 -O2 -O3 > g++-2.95 ok error error error > g++-3.3 ok error error error > g++-3.4 ok ok error error > g++-4.0 ok error error error > g++-4.1 ok error error error > > g++ -v output for each compiler it further down. > > Have I done something wrong or is this something for the bugzilla?
it's hard to tell with code of this size; if you can make the testcase smaller, it would definitely help. However, given that so many versions of gcc cause this error, I suspect there is something wrong with your code (possibly invoking some undefined behavior, using uninitialized variable, sensitivity to rounding errors, or something like that). Zdenek
