I have used the -mcpu=405 and 440 in trials to see what the assembly looks like and in both cases it does differ from the commercial variant. The differences are generally inversions of 2-3 instructions. Such as this function call start from GCC, stwu 1,-32(1) mflr 0 In the commercial variant it looks like this, mflr 0 stwu 1,-32(1) The Power PC is sensitive to instruction ordering as it can do a fetches while executing instructions already in the pipeline. The vendor has speed data showing quite a large gap over GCC in testing, which is also our experience. On Thu, 2009-05-07 at 06:43 -0700, John (Eljay) Love-Jensen wrote: > Hi marian, > > > My question has the assembly ordering for the 405 and 440 been > > optimised? > > I presume you are using GCC 4.4.0, since you did not specify. > > When you use the GCC compiler, are you using the -mtune flag to specify > which CPU you want to optimize for? > > Sincerely, > --Eljay >
