thanks for Jeff and Vladimir. I will try the way that Jeff provided In fact, I don't quite understand what reload do and when reload do after I read gcc's wiki... 2009/10/7 Jeff Law <law@xxxxxxxxxx>: > On 10/06/09 21:20, Vladimir Makarov wrote: >> >> kito wrote: >>> >>> Hello everybody: >>> I want to count the number of spilling. >>> I have try to compile file with -fdump-rtl-ira >>> And then use `grep Spilling *.ira | wc -l` >>> Does it's right way to get the number of spilling? >>> >> That is a wrong way to find real spills. Lines with Spilling is actually >> reported by reload pass and it means only that reload is checking >> constraints for insns (it is not real spills). Reload pass can do several >> such iterations. The more hard registers usages, the more iterations are >> usually needed. Therefore you are getting that lines with 'Spilling' have >> -O1 < -O2 < -O3. > > Also note that some spills are significantly more costly than others. > Secondary & tertiary reloads, secondary memory and the like all come to > mind. > > If you just want static counts, an easy way to do this would be to scan the > insns after IRA has completed. Mark each uid encountered in a bitmap. Then > rescan the insns after reload (or better, after the post-reload optimizers) > -- clearly any insns not in the bitmap are spill code. > > That's not perfect as it'll miss cases where we reload by replacing a REG > with a MEM and the result is a valid insn, but it'll be a hell of a lot > closer than trying to scan the .ira dumps. > > I'm pondering such a scheme, combined with classifying the spill insns > (load, store, arith) and block entry profiling to get a dynamic picture of > the spill code we're executing. > > jeff > >
