This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: IEEE 754 and fused-madd (was: Re: patch: rs6000 specific)


All right, so I need to generate additional FMA patterns by modifying 
combine.
Our FP expert says all the required transformations are IEEE-compliant.
Before I get too far into it, does anybody want to dispute this?  Here are
the patterns.  The claim is that each of them can be transformed safely
into the first one in its group.

fmadd:
     A*C + B
     B + A*C
fnmsub:
     -(A*C - B)
     ((-A)*C) + B
     -((-B) + A*C)
     B - A*C
fmsub:
     A*C -B
     -B + A*C
     -(B - A*C)
     -((-A)*C + B)
fnmadd:
     -(A*C + B)
     ((-A)*C) -B
     (-B) - A*C
     -(B + A*C)


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]