https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54488
--- Comment #3 from Evgeniya Maenkova <evgeniya.maenkova at gmail dot com> --- Could you please clarify your comment #36 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46590#c36) in PR4596? I mean "LIM is now the pass that pushes memory usage to 1.8GB - all other optimization passes are happy with just ~800MB." How did you measure lim impact (1,8G)? (Was it by -ftime-report being run with/without lim optimization? Or was it top? Or some other tool which allow to see memory footprint for each optimization pass.) I can see this (for the full test case om 46590). ( I mean based on -ftime-report we see ~5,5Mb, but this only GC memory, right? ): MAIN__ main Analyzing compilation unit {GC 41969k -> 36104k} {GC 72488k -> 52189k} {GC 70118k -> 55388k}Performing interprocedural optimizations <*free_lang_data> <visibility> <early_local_cleanups> {GC 81054k -> 73552k} <free-inline-summary> <whole-program> <profile_estimate> <devirt> <cp> <inline> <pure-const> <static-var> <single-use> <comdats>Assembling functions: MAIN__ {GC 137793k -> 78714k} {GC 107079k -> 70685k} {GC 97203k -> 77229k} {GC 100487k -> 71679k} {GC 148921k -> 129443k} {GC 190666k -> 128409k} {GC 168488k -> 127341k} main Execution times (seconds) phase setup : 0.05 ( 0%) usr 0.01 ( 0%) sys 0.08 ( 0%) wall 107 kB ( 0%) ggc phase parsing : 13.79 ( 1%) usr 0.15 ( 0%) sys 13.94 ( 1%) wall 41869 kB ( 7%) ggc phase lang. deferred : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 0 kB ( 0%) ggc phase opt and generate :2103.63 (99%) usr 89.40 (100%) sys2195.36 (99%) wall 519770 kB (93%) ggc phase finalize : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc garbage collection : 5.42 ( 0%) usr 0.04 ( 0%) sys 5.48 ( 0%) wall 0 kB ( 0%) ggc callgraph construction : 0.91 ( 0%) usr 0.00 ( 0%) sys 0.88 ( 0%) wall 7644 kB ( 1%) ggc callgraph optimization : 0.12 ( 0%) usr 0.00 ( 0%) sys 0.13 ( 0%) wall 0 kB ( 0%) ggc ipa dead code removal : 0.04 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc ipa cp : 0.18 ( 0%) usr 0.00 ( 0%) sys 0.19 ( 0%) wall 256 kB ( 0%) ggc ipa inlining heuristics : 2.54 ( 0%) usr 0.00 ( 0%) sys 2.54 ( 0%) wall 3253 kB ( 1%) ggc ipa profile : 0.27 ( 0%) usr 0.00 ( 0%) sys 0.27 ( 0%) wall 0 kB ( 0%) ggc ipa pure const : 0.42 ( 0%) usr 0.00 ( 0%) sys 0.42 ( 0%) wall 0 kB ( 0%) ggc cfg construction : 0.31 ( 0%) usr 0.01 ( 0%) sys 0.33 ( 0%) wall 2278 kB ( 0%) ggc cfg cleanup : 1.75 ( 0%) usr 0.05 ( 0%) sys 1.90 ( 0%) wall 752 kB ( 0%) ggc CFG verifier : 22.85 ( 1%) usr 0.10 ( 0%) sys 22.83 ( 1%) wall 0 kB ( 0%) ggc trivially dead code : 1.12 ( 0%) usr 0.00 ( 0%) sys 1.10 ( 0%) wall 0 kB ( 0%) ggc df scan insns : 2.79 ( 0%) usr 0.12 ( 0%) sys 2.92 ( 0%) wall 0 kB ( 0%) ggc df multiple defs : 0.75 ( 0%) usr 0.01 ( 0%) sys 0.77 ( 0%) wall 0 kB ( 0%) ggc df reaching defs : 76.35 ( 4%) usr 68.69 (77%) sys 144.67 ( 7%) wall 0 kB ( 0%) ggc df live regs : 6.93 ( 0%) usr 0.79 ( 1%) sys 7.65 ( 0%) wall 0 kB ( 0%) ggc df live&initialized regs: 2.74 ( 0%) usr 0.69 ( 1%) sys 3.41 ( 0%) wall 0 kB ( 0%) ggc df use-def / def-use chains: 1.04 ( 0%) usr 0.00 ( 0%) sys 1.10 ( 0%) wall 0 kB ( 0%) ggc df reg dead/unused notes: 4.37 ( 0%) usr 0.00 ( 0%) sys 4.36 ( 0%) wall 6401 kB ( 1%) ggc register information : 0.56 ( 0%) usr 0.00 ( 0%) sys 0.55 ( 0%) wall 0 kB ( 0%) ggc alias analysis : 3.12 ( 0%) usr 0.00 ( 0%) sys 3.15 ( 0%) wall 9226 kB ( 2%) ggc alias stmt walking : 632.31 (30%) usr 2.05 ( 2%) sys 635.16 (29%) wall 2380 kB ( 0%) ggc register scan : 0.21 ( 0%) usr 0.00 ( 0%) sys 0.21 ( 0%) wall 274 kB ( 0%) ggc rebuild jump labels : 0.54 ( 0%) usr 0.01 ( 0%) sys 0.54 ( 0%) wall 0 kB ( 0%) ggc parser (global) : 13.79 ( 1%) usr 0.15 ( 0%) sys 13.94 ( 1%) wall 41869 kB ( 7%) ggc early inlining heuristics: 0.01 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 0 kB ( 0%) ggc inline parameters : 1.06 ( 0%) usr 0.00 ( 0%) sys 1.07 ( 0%) wall 1 kB ( 0%) ggc integration : 0.04 ( 0%) usr 0.00 ( 0%) sys 0.04 ( 0%) wall 0 kB ( 0%) ggc tree gimplify : 5.23 ( 0%) usr 0.04 ( 0%) sys 5.26 ( 0%) wall 38114 kB ( 7%) ggc tree eh : 0.14 ( 0%) usr 0.00 ( 0%) sys 0.14 ( 0%) wall 0 kB ( 0%) ggc tree CFG construction : 0.49 ( 0%) usr 0.02 ( 0%) sys 0.52 ( 0%) wall 13855 kB ( 2%) ggc tree CFG cleanup : 93.20 ( 4%) usr 0.37 ( 0%) sys 93.55 ( 4%) wall 3894 kB ( 1%) ggc tree tail merge : 0.28 ( 0%) usr 0.00 ( 0%) sys 0.26 ( 0%) wall 0 kB ( 0%) ggc tree VRP : 15.11 ( 1%) usr 0.66 ( 1%) sys 15.87 ( 1%) wall 15190 kB ( 3%) ggc tree copy propagation : 1.96 ( 0%) usr 0.01 ( 0%) sys 1.96 ( 0%) wall 7 kB ( 0%) ggc tree PTA : 68.62 ( 3%) usr 0.35 ( 0%) sys 68.97 ( 3%) wall 5002 kB ( 1%) ggc tree PHI insertion : 0.34 ( 0%) usr 0.01 ( 0%) sys 0.34 ( 0%) wall 6280 kB ( 1%) ggc tree SSA rewrite : 2.01 ( 0%) usr 0.01 ( 0%) sys 2.01 ( 0%) wall 12549 kB ( 2%) ggc tree SSA other : 0.56 ( 0%) usr 0.26 ( 0%) sys 0.82 ( 0%) wall 0 kB ( 0%) ggc tree SSA incremental : 3.62 ( 0%) usr 0.05 ( 0%) sys 3.78 ( 0%) wall 9579 kB ( 2%) ggc tree operand scan : 2.71 ( 0%) usr 0.27 ( 0%) sys 3.02 ( 0%) wall 12294 kB ( 2%) ggc dominator optimization : 637.95 (30%) usr 0.02 ( 0%) sys 637.98 (29%) wall 11954 kB ( 2%) ggc tree SRA : 2.15 ( 0%) usr 0.01 ( 0%) sys 2.14 ( 0%) wall 172 kB ( 0%) ggc isolate eroneous paths : 0.09 ( 0%) usr 0.00 ( 0%) sys 0.09 ( 0%) wall 0 kB ( 0%) ggc tree CCP : 24.10 ( 1%) usr 0.02 ( 0%) sys 24.14 ( 1%) wall 2100 kB ( 0%) ggc tree PHI const/copy prop: 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 7 kB ( 0%) ggc tree split crit edges : 0.12 ( 0%) usr 0.00 ( 0%) sys 0.13 ( 0%) wall 1860 kB ( 0%) ggc tree reassociation : 0.27 ( 0%) usr 0.00 ( 0%) sys 0.27 ( 0%) wall 0 kB ( 0%) ggc tree PRE : 11.70 ( 1%) usr 0.35 ( 0%) sys 13.19 ( 1%) wall 10433 kB ( 2%) ggc tree FRE : 16.29 ( 1%) usr 0.12 ( 0%) sys 15.63 ( 1%) wall 12925 kB ( 2%) ggc tree code sinking : 0.72 ( 0%) usr 0.00 ( 0%) sys 0.72 ( 0%) wall 291 kB ( 0%) ggc tree linearize phis : 0.18 ( 0%) usr 0.00 ( 0%) sys 0.18 ( 0%) wall 1 kB ( 0%) ggc tree forward propagate : 0.82 ( 0%) usr 0.02 ( 0%) sys 0.87 ( 0%) wall 613 kB ( 0%) ggc tree phiprop : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 0 kB ( 0%) ggc tree conservative DCE : 0.99 ( 0%) usr 0.24 ( 0%) sys 1.14 ( 0%) wall 127 kB ( 0%) ggc tree aggressive DCE : 4.79 ( 0%) usr 0.10 ( 0%) sys 5.04 ( 0%) wall 6137 kB ( 1%) ggc tree buildin call DCE : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 0 kB ( 0%) ggc tree DSE : 5.18 ( 0%) usr 0.00 ( 0%) sys 5.17 ( 0%) wall 2048 kB ( 0%) ggc PHI merge : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc tree loop bounds : 1.12 ( 0%) usr 0.00 ( 0%) sys 1.14 ( 0%) wall 2311 kB ( 0%) ggc tree loop invariant motion: 0.57 ( 0%) usr 0.00 ( 0%) sys 0.57 ( 0%) wall 0 kB ( 0%) ggc tree canonical iv : 1.54 ( 0%) usr 0.02 ( 0%) sys 1.53 ( 0%) wall 3193 kB ( 1%) ggc scev constant prop : 0.12 ( 0%) usr 0.00 ( 0%) sys 0.16 ( 0%) wall 514 kB ( 0%) ggc complete unrolling : 45.19 ( 2%) usr 1.07 ( 1%) sys 46.24 ( 2%) wall 54512 kB (10%) ggc tree iv optimization : 16.47 ( 1%) usr 0.11 ( 0%) sys 16.67 ( 1%) wall 15757 kB ( 3%) ggc tree copy headers : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc tree SSA uncprop : 0.10 ( 0%) usr 0.00 ( 0%) sys 0.09 ( 0%) wall 0 kB ( 0%) ggc tree rename SSA copies : 0.29 ( 0%) usr 0.00 ( 0%) sys 0.29 ( 0%) wall 0 kB ( 0%) ggc tree SSA verifier : 48.93 ( 2%) usr 0.00 ( 0%) sys 49.03 ( 2%) wall 0 kB ( 0%) ggc tree STMT verifier : 119.16 ( 6%) usr 0.00 ( 0%) sys 119.09 ( 5%) wall 0 kB ( 0%) ggc tree switch conversion : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc tree strlen optimization: 0.08 ( 0%) usr 0.00 ( 0%) sys 0.08 ( 0%) wall 0 kB ( 0%) ggc callgraph verifier : 2.82 ( 0%) usr 0.00 ( 0%) sys 2.84 ( 0%) wall 0 kB ( 0%) ggc dominance frontiers : 0.08 ( 0%) usr 0.00 ( 0%) sys 0.07 ( 0%) wall 0 kB ( 0%) ggc dominance computation : 3.47 ( 0%) usr 0.02 ( 0%) sys 3.36 ( 0%) wall 0 kB ( 0%) ggc control dependences : 0.03 ( 0%) usr 0.00 ( 0%) sys 0.04 ( 0%) wall 0 kB ( 0%) ggc out of ssa : 1.27 ( 0%) usr 0.00 ( 0%) sys 1.27 ( 0%) wall 3 kB ( 0%) ggc expand vars : 0.70 ( 0%) usr 0.00 ( 0%) sys 0.70 ( 0%) wall 2685 kB ( 0%) ggc expand : 9.20 ( 0%) usr 0.07 ( 0%) sys 9.47 ( 0%) wall 75267 kB (13%) ggc post expand cleanups : 0.25 ( 0%) usr 0.00 ( 0%) sys 0.26 ( 0%) wall 0 kB ( 0%) ggc lower subreg : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc forward prop : 2.40 ( 0%) usr 0.02 ( 0%) sys 2.42 ( 0%) wall 4462 kB ( 1%) ggc CSE : 5.95 ( 0%) usr 0.00 ( 0%) sys 5.94 ( 0%) wall 3584 kB ( 1%) ggc dead code elimination : 1.08 ( 0%) usr 0.00 ( 0%) sys 1.10 ( 0%) wall 0 kB ( 0%) ggc dead store elim1 : 3.79 ( 0%) usr 0.03 ( 0%) sys 3.83 ( 0%) wall 13064 kB ( 2%) ggc dead store elim2 : 6.27 ( 0%) usr 0.00 ( 0%) sys 6.27 ( 0%) wall 13104 kB ( 2%) ggc loop init : 50.96 ( 2%) usr 0.01 ( 0%) sys 50.95 ( 2%) wall 28100 kB ( 5%) ggc loop invariant motion : 5.97 ( 0%) usr 12.23 (14%) sys 18.62 ( 1%) wall 14 kB ( 0%) ggc loop fini : 0.10 ( 0%) usr 0.00 ( 0%) sys 0.13 ( 0%) wall 0 kB ( 0%) ggc CPROP : 2.88 ( 0%) usr 0.00 ( 0%) sys 2.90 ( 0%) wall 0 kB ( 0%) ggc PRE : 0.05 ( 0%) usr 0.00 ( 0%) sys 0.05 ( 0%) wall 0 kB ( 0%) ggc CSE 2 : 5.33 ( 0%) usr 0.01 ( 0%) sys 5.33 ( 0%) wall 2902 kB ( 1%) ggc branch prediction : 1.63 ( 0%) usr 0.00 ( 0%) sys 1.63 ( 0%) wall 1851 kB ( 0%) ggc combiner : 3.75 ( 0%) usr 0.01 ( 0%) sys 3.85 ( 0%) wall 5136 kB ( 1%) ggc if-conversion : 0.11 ( 0%) usr 0.00 ( 0%) sys 0.15 ( 0%) wall 0 kB ( 0%) ggc integrated RA : 17.72 ( 1%) usr 0.08 ( 0%) sys 17.86 ( 1%) wall 34933 kB ( 6%) ggc LRA non-specific : 5.26 ( 0%) usr 0.03 ( 0%) sys 5.27 ( 0%) wall 5148 kB ( 1%) ggc LRA virtuals elimination: 2.09 ( 0%) usr 0.00 ( 0%) sys 2.11 ( 0%) wall 10650 kB ( 2%) ggc LRA create live ranges : 0.49 ( 0%) usr 0.00 ( 0%) sys 0.49 ( 0%) wall 857 kB ( 0%) ggc LRA hard reg assignment : 0.15 ( 0%) usr 0.00 ( 0%) sys 0.15 ( 0%) wall 0 kB ( 0%) ggc reload : 0.03 ( 0%) usr 0.00 ( 0%) sys 0.04 ( 0%) wall 0 kB ( 0%) ggc reload CSE regs : 7.30 ( 0%) usr 0.00 ( 0%) sys 7.29 ( 0%) wall 20497 kB ( 4%) ggc ree : 0.12 ( 0%) usr 0.00 ( 0%) sys 0.15 ( 0%) wall 0 kB ( 0%) ggc thread pro- & epilogue : 1.16 ( 0%) usr 0.00 ( 0%) sys 1.16 ( 0%) wall 3 kB ( 0%) ggc if-conversion 2 : 0.06 ( 0%) usr 0.00 ( 0%) sys 0.06 ( 0%) wall 0 kB ( 0%) ggc combine stack adjustments: 0.19 ( 0%) usr 0.00 ( 0%) sys 0.18 ( 0%) wall 84 kB ( 0%) ggc peephole 2 : 0.86 ( 0%) usr 0.00 ( 0%) sys 0.84 ( 0%) wall 405 kB ( 0%) ggc hard reg cprop : 4.49 ( 0%) usr 0.05 ( 0%) sys 4.53 ( 0%) wall 2 kB ( 0%) ggc scheduling 2 : 15.49 ( 1%) usr 0.06 ( 0%) sys 15.55 ( 1%) wall 4668 kB ( 1%) ggc machine dep reorg : 0.04 ( 0%) usr 0.00 ( 0%) sys 0.03 ( 0%) wall 0 kB ( 0%) ggc reorder blocks : 1.08 ( 0%) usr 0.02 ( 0%) sys 1.15 ( 0%) wall 3889 kB ( 1%) ggc shorten branches : 0.94 ( 0%) usr 0.00 ( 0%) sys 0.94 ( 0%) wall 0 kB ( 0%) ggc final : 2.83 ( 0%) usr 0.03 ( 0%) sys 2.90 ( 0%) wall 12173 kB ( 2%) ggc variable output : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 2 kB ( 0%) ggc tree if-combine : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 0 kB ( 0%) ggc straight-line strength reduction: 0.85 ( 0%) usr 0.00 ( 0%) sys 0.84 ( 0%) wall 276 kB ( 0%) ggc rest of compilation : 3.58 ( 0%) usr 0.00 ( 0%) sys 3.70 ( 0%) wall 1791 kB ( 0%) ggc remove unused locals : 0.92 ( 0%) usr 0.00 ( 0%) sys 0.93 ( 0%) wall 0 kB ( 0%) ggc address taken : 0.60 ( 0%) usr 0.00 ( 0%) sys 0.61 ( 0%) wall 0 kB ( 0%) ggc unaccounted todo : 3.97 ( 0%) usr 0.04 ( 0%) sys 4.14 ( 0%) wall 0 kB ( 0%) ggc verify loop closed : 0.72 ( 0%) usr 0.00 ( 0%) sys 0.75 ( 0%) wall 0 kB ( 0%) ggc verify RTL sharing : 21.04 ( 1%) usr 0.00 ( 0%) sys 21.04 ( 1%) wall 0 kB ( 0%) ggc repair loop structures : 1.50 ( 0%) usr 0.00 ( 0%) sys 1.58 ( 0%) wall 0 kB ( 0%) ggc TOTAL :2117.50 89.56 2209.41 561747 kB Extra diagnostic checks enabled; compiler may run slowly. Configure with --enable-checking=release to disable checks. My command line was: time /users/egm/gcc_objdir/libexec/gcc/i686-pc-linux-gnu/5.0.0/f951 -ftime-report -O2 gener-max.f90 > max_out 2>&1 real 36m49.416s user 35m17.508s sys 1m29.654s