[Bug c++/20674] New: unexpected result from floating compare

["piaget at us dot ibm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Small .C program shows a problem where a value of 1.0 is calculated, but that 
value falls through 2 if-checks ... one checks for "if (val <= 1.0)" , the next 
checks for "if (val > 1.0)" ... one of these if checks must be true but neither 
true leg is taken.

problem surfaces at optimization level -O1 (also tested -O2 and -O3 ... same 
problem)
problem goes away with -ffloat-store , although I feel this is a logic problem 
and not a precision problem.
problem goes away if compiled as .c (with pass-by-reference removed)

g++ -v -save-temps -O1 -o tmp1 tmp1.C

This is my first bug ... I am going to committ ... may add attachments later if 
not given the opportunity now

-- 
           Summary: unexpected result from floating compare
           Product: gcc
           Version: 3.4.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: piaget at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i586-mandrake-linux-gnu
GCC target triplet: i586-mandrake-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20674