On Sat, 6 Dec 2008 22:13:46 +1100 Paul Mackerras <[EMAIL PROTECTED]> wrote:
> Amit Uttamchandani writes: > > > I'm learning the PPC architecture and I have a PowerBook G4 (7410) > > 500MHz. Looking at the datasheet for the processor, it has support for > > hardware speculation which allows out-of-order execution. > > > > I wanted to test program run times by compiling using gcc with flags > > that enable and then disable support for this hardware speculation > > feature. This is just to see the difference between program run times. > > > > Any ideas which flags/options I should be using in gcc? > > It's not something that gcc has any control over. In fact there isn't > any way to turn off the out-of-order execution that I know of. > > Paul. Thanks for the reply. You're right, I guess we can't disable the "hardware" directly but if we let gcc know about this then it is possible that it will do further optimizations correct? For example, I can compile a C program using regular gcc without any options and then adding the following and comparing the differences: "-mcpu=7400 -O2 -pipe -maltivec -mabi=altivec" This way the compiler "knows" about the hardware and tries to optimize the program based on that. What do you think? Thanks, Amit -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
