"V. Karthik Kumar" <[EMAIL PROTECTED]> writes: > I require help with some work i've been doing lately on gcc (4.2.1 > tree). I have managed to put some code in. > > Now, for function compilation, i require to invoke the i386 (as of > now) backend multiple times and with different switches; one time with > 3dnow!, another with mmx, another with sse2. And floating point code > will require usage of both 387 and sse. > > It is intended that multiple archs are passed as part of the -march > option. (-m3dnow,sse2,sse3 or -march=k6,nocona or maybe > -march=sse2,sse3) > > Eventually, some of this code may also get used in the PowerPC backend > (one time with AltiVec and one time without).. > > it is intended that multiple versions of functions would go into the > assembly file; The global data segment would be created only once, > aligned to targeted instruction sets' requirement for efficient > accesses (if mmx and sse, alignment might be 8 bytes than 4). > > I have started working, but not sure which parts I should be touching > by now. > > Please give me your suggestions. Any help in this regard would be > greatly appreciated.
The first thing you need to do is move to mainline, and take advantage of the patch by Sandra Loosemore, David Ung, and Nigel Stephens to add TARGET_SET_CURRENT_FUNCTION. That is the framework you'll need to change the architecture on a per-function basis. Then you'll need to figure out how to clone the function the way the inliner does, and presumably give each copy different names or something--you didn't mention how you plan to handle that issue. Then you can wind up compiling each function with different parameters. This is a nontrivial exercise, but an interesting one. Good luck. Ian
