https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80838
Jan Hubicka <hubicka at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-07-05
CC| |hubicka at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #4 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
The same slowdown is seen when compiling combine.ii, too, so it is not caused
by tramp3d not being representative. With LTO:
Performance counter stats for './xgcc -B ./ /aux/hubicka/combine.ii -O2 -S':
6078.849031 task-clock (msec) # 0.998 CPUs utilized
616 context-switches # 0.101 K/sec
2 cpu-migrations # 0.000 K/sec
44,730 page-faults # 0.007 M/sec
18,048,640,894 cycles # 2.969 GHz
3,077,757,657 stalled-cycles-frontend # 17.05% frontend cycles
idle
5,647,264,874 stalled-cycles-backend # 31.29% backend cycles
idle
14,751,268,913 instructions # 0.82 insns per cycle
# 0.38 stalled cycles per
insn
3,221,027,271 branches # 529.875 M/sec
146,203,951 branch-misses # 4.54% of all branches
6.088293716 seconds time elapsed
Without LTO:
Performance counter stats for './xgcc -B ./ /aux/hubicka/combine.ii -O2 -S':
5815.257284 task-clock (msec) # 0.998 CPUs utilized
594 context-switches # 0.102 K/sec
3 cpu-migrations # 0.001 K/sec
44,736 page-faults # 0.008 M/sec
17,305,115,662 cycles # 2.976 GHz
2,736,627,618 stalled-cycles-frontend # 15.81% frontend cycles
idle
5,580,251,004 stalled-cycles-backend # 32.25% backend cycles
idle
13,952,236,872 instructions # 0.81 insns per cycle
# 0.40 stalled cycles per
insn
3,147,743,704 branches # 541.291 M/sec
145,597,831 branch-misses # 4.63% of all branches
5.824996172 seconds time elapsed
Sadly profile seems sufficiently flat to make it hard to work out what is going
on. With LTO:
Samples: 24K of event 'cycles', Event count (approx.): 18314340157
2.67% cc1plus cc1plus [.] bitmap_set_bit
1.53% cc1plus libc-2.19.so [.] _int_malloc
1.19% cc1plus cc1plus [.] df_worklist_dataflow
1.07% cc1plus cc1plus [.] get_ref_base_and_extent
1.05% cc1plus cc1plus [.] ggc_internal_alloc
1.04% cc1plus cc1plus [.] bitmap_ior_into
1.01% cc1plus cc1plus [.] pre_and_rev_post_order_compute_fn
0.92% cc1plus cc1plus [.] lra_create_live_ranges_1
0.86% cc1plus cc1plus [.] record_reg_classes
0.82% cc1plus cc1plus [.] df_note_compute
0.79% cc1plus cc1plus [.] bitmap_clear_bit
0.65% cc1plus cc1plus [.] walk_tree_1
0.63% cc1plus libc-2.19.so [.] _int_free
0.58% cc1plus cc1plus [.] fsm_find_thread_path
0.57% cc1plus cc1plus [.] flags_from_decl_or_type
0.56% cc1plus cc1plus [.] cleanup_cfg
0.55% cc1plus cc1plus [.] wide_int_to_tree
0.55% cc1plus cc1plus [.] df_live_bb_local_compute
0.54% cc1plus cc1plus [.] et_set_father
0.54% cc1plus cc1plus [.] bitmap_bit_p
0.53% cc1plus cc1plus [.] bitmap_copy
0.53% cc1plus cc1plus [.] operand_equal_p
0.52% cc1plus cc1plus [.] sched_analyze_insn
0.52% cc1plus cc1plus [.] reload_cse_simplify_operands
0.51% cc1plus cc1plus [.] (anonymous
namespace)::dom_info::calc_idoms
0.50% cc1plus cc1plus [.] cse_insn
0.47% cc1plus [kernel.kallsyms] [k] clear_page
Without LTO:
Samples: 23K of event 'cycles', Event count (approx.): 17586270321
Overhead Command Shared Object Symbol
2.88% cc1plus cc1plus [.] bitmap_set_bit
1.72% cc1plus libc-2.19.so [.] _int_malloc
1.05% cc1plus cc1plus [.] ggc_internal_alloc
1.04% cc1plus cc1plus [.] get_ref_base_and_extent
1.03% cc1plus cc1plus [.] pre_and_rev_post_order_compute_fn
0.98% cc1plus cc1plus [.] lra_create_live_ranges_1
0.97% cc1plus cc1plus [.] bitmap_ior_into
0.88% cc1plus cc1plus [.] record_operand_costs
0.82% cc1plus cc1plus [.] bitmap_clear_bit
0.80% cc1plus cc1plus [.] df_note_compute
0.79% cc1plus cc1plus [.] df_worklist_dataflow
0.72% cc1plus libc-2.19.so [.] _int_free
0.71% cc1plus cc1plus [.] (anonymous
namespace)::dom_info::calc_idoms
0.70% cc1plus cc1plus [.] run_fast_df_dce
0.65% cc1plus cc1plus [.] bitmap_bit_p
0.63% cc1plus cc1plus [.] bitmap_copy
0.62% cc1plus cc1plus [.] walk_tree_1
0.58% cc1plus cc1plus [.] et_set_father
0.55% cc1plus [kernel.kallsyms] [k] clear_page
0.53% cc1plus cc1plus [.] df_live_local_compute
0.51% cc1plus cc1plus [.] flags_from_decl_or_type
0.49% cc1plus cc1plus [.] et_below
0.47% cc1plus cc1plus [.] df_analyze
0.46% cc1plus cc1plus [.] cse_insn
0.46% cc1plus cc1plus [.] cleanup_cfg
0.45% cc1plus cc1plus [.] inverted_post_order_compute
0.45% cc1plus cc1plus [.] constrain_operands
0.44% cc1plus cc1plus [.] reload_cse_simplify_operands
0.43% cc1plus cc1plus [.] fsm_find_thread_path
0.43% cc1plus libc-2.19.so [.] memset
Measuring instructions is slightly more precise.
3.02% cc1plus cc1plus [.] bitmap_set_bit
1.33% cc1plus cc1plus [.] get_ref_base_and_extent
1.18% cc1plus libc-2.19.so [.] _int_malloc
1.06% cc1plus cc1plus [.] record_reg_classes
1.06% cc1plus cc1plus [.] bitmap_ior_into
1.03% cc1plus cc1plus [.] bitmap_clear_bit
1.02% cc1plus cc1plus [.] df_worklist_dataflow
0.94% cc1plus cc1plus [.] df_note_compute
0.94% cc1plus cc1plus [.] df_insn_refs_collect
0.88% cc1plus cc1plus [.] ggc_internal_alloc
0.86% cc1plus cc1plus [.] lra_create_live_ranges_1
0.82% cc1plus cc1plus [.] pre_and_rev_post_order_compute_fn
0.77% cc1plus cc1plus [.] operand_equal_p
0.71% cc1plus libc-2.19.so [.] _int_free
0.68% cc1plus cc1plus [.] inchash::add_expr
0.68% cc1plus cc1plus [.] bitmap_bit_p
0.68% cc1plus cc1plus [.] walk_tree_1
0.68% cc1plus cc1plus [.] fsm_find_thread_path
0.66% cc1plus cc1plus [.] reload_cse_simplify_operands
0.65% cc1plus cc1plus [.] sched_analyze_insn
0.58% cc1plus cc1plus [.] (anonymous
namespace)::dom_info::calc_idoms
0.55% cc1plus cc1plus [.] cleanup_cfg
0.53% cc1plus cc1plus [.] et_set_father
0.51% cc1plus cc1plus [.] constrain_operands
0.50% cc1plus cc1plus [.] cse_insn
non-lto:
3.25% cc1plus cc1plus [.] bitmap_set_bit
1.34% cc1plus cc1plus [.] get_ref_base_and_extent
1.26% cc1plus libc-2.19.so [.] _int_malloc
1.19% cc1plus cc1plus [.] record_operand_costs
1.02% cc1plus cc1plus [.] bitmap_ior_into
1.00% cc1plus cc1plus [.] lra_create_live_ranges_1
1.00% cc1plus cc1plus [.] bitmap_clear_bit
0.99% cc1plus cc1plus [.] df_note_compute
0.94% cc1plus cc1plus [.] pre_and_rev_post_order_compute_fn
0.91% cc1plus cc1plus [.] ggc_internal_alloc
0.84% cc1plus cc1plus [.] df_insn_refs_collect
0.81% cc1plus cc1plus [.] inchash::add_expr
0.76% cc1plus cc1plus [.] bitmap_bit_p
0.76% cc1plus cc1plus [.] operand_equal_p
0.75% cc1plus cc1plus [.] sched_analyze_insn
0.72% cc1plus cc1plus [.] reload_cse_simplify_operands
0.64% cc1plus cc1plus [.] (anonymous
namespace)::dom_info::calc_idoms
0.64% cc1plus cc1plus [.] walk_tree_1
0.63% cc1plus cc1plus [.] et_set_father
0.60% cc1plus cc1plus [.] run_fast_df_dce
0.59% cc1plus cc1plus [.] df_worklist_dataflow
0.57% cc1plus libc-2.19.so [.] _int_free
0.57% cc1plus cc1plus [.] _cpp_lex_token
0.55% cc1plus cc1plus [.] cse_insn
0.55% cc1plus cc1plus [.] cleanup_tree_cfg
0.54% cc1plus cc1plus [.] find_costs_and_classes
0.51% cc1plus cc1plus [.] constrain_operands
