On Thu, 2019-12-19 at 17:06 -0600, Qing Zhao wrote: > Hi, Dmitry, > > Thanks for the responds. > > Yes, routine size only cannot determine the complexity of the routine. > Different compiler analysis might have different formula with multiple > parameters to compute its complexity. > > However, the common issue is: when the complexity of a specific routine for a > specific compiler analysis exceeds a threshold, the compiler might consume > all the available memory and abort the compilation. > > Therefore, in order to avoid the failed compilation due to out of memory, > some compilers might set a threshold for the complexity of a specific > compiler analysis (for example, the more aggressive data flow analysis), when > the threshold is met, the specific aggressive analysis will be turned off for > this specific routine. Or the optimization level will be lowered for the > specific routine (and given a warning during compilation time for such > adjustment). > > I am wondering whether GCC has such capability? Or any option provided to > increase or decrease the threshold for some of the common analysis (for > example, data flow)? > There are various places where if we hit a limit, then we throttle optimization. But it's not done consistently or pervasively.
Those limits are typically around things like CFG complexity. We do _not_ try to recover after an out of memory error, or anything like that. jeff >
