> > On Mon, 23 Nov 2020, Jan Hubicka wrote: > > > > > > On Mon, 23 Nov 2020, Jan Hubicka wrote: > > > > > > > > > Hi, > > > > > tree-streamer-in currently calls init_tree_ssa that calls > > > > > init_ssanames > > > > > that allocates space in ssa_names array for 50 names. Later it > > > > > streams > > > > > in the count and calls init_tree_ssa again, this time with correct > > > > > count, which is rounded up to 50 and allocated again leaking the first > > > > > array. > > > > > > > > > > This patch fixes it by adding extra argument to init_tree_ssa > > > > > specifing > > > > > whether ssa names should be initialized. There are few places where > > > > > we > > > > > initialize ssa and only lto streaming is special, so i think extra arg > > > > > works well here. > > > > > > > > > > I am not quite sure about the 50MB default. I think it was made > > > > > before > > > > > ggc_free was implemented (so resizing vectors was expensive) and when > > > > > we > > > > > had only one function in SSA form at a time. Most of functions in C++ > > > > > will probably need fewer than 50 SSA names until inlining. > > > > > > > > > > This saves 21MB of WPA linking libxul.
I actually was overly pesimistic here. It changes: GGC memory Leak Garbage Freed Overhead Times -------------------------------------------------------------------------------------------------------------------------------------------- Total 2116M:100.0% 779M:100.0% 3744M:100.0% 312M:100.0% 49M -------------------------------------------------------------------------------------------------------------------------------------------- to -------------------------------------------------------------------------------------------------------------------------------------------- GGC memory Leak Garbage Freed Overhead Times -------------------------------------------------------------------------------------------------------------------------------------------- Total 2137M:100.0% 916M:100.0% 3813M:100.0% 390M:100.0% 49M -------------------------------------------------------------------------------------------------------------------------------------------- So in addition to 21MB of leak memory (i.e. function bodies still needed) also 137MB of garbage (i.e. functions eliminated by ICF or dead code elimination) Honza
