On Fri, Feb 5, 2010 at 7:32 AM, tatwai chong <[email protected]> wrote:
> I want to ask why don't implement the RA for ARM even the framework of > RA on ARM is existed ? > On ARM the cost of register allocation outweighs its benefits. The main costs are (1) an increase in code size due to saving and restoring live registers around calls and (2) an increase in compile time due to register allocation decisions at control-flow merge points. The benefit is obviously a performance gain. This benefit is greatest when combined with inlining (of arithmetic operations or property loads and stores for instance) because we can keep values live in registers. For code that contains a lot of calls, values end up in memory anyway. On ARM, we prefer compact code and to a lesser extent, quick compilation. For that reason, we do not inline as aggressively as on other platforms, making the register allocation benefit less dramatic. -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users
