https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94360
Bug ID: 94360
Summary: 6% run-time regression of 502.gcc_r against GCC 9 when
compiled with -O2 and both PGO and LTO
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: jamborm at gcc dot gnu.org
CC: hubicka at gcc dot gnu.org, marxin at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-linux
Target: x86_64-linux
When built at -O2, generic march/mtune and with both PGO and LTO and
current trunk/master, SPEC 2017 INTrate 502.gcc_r is 6% slower when
run on and AMD Zen2-based CPU - and about 4.8% slower on Intel Cascade
Lake.
Looking at how the run-time of the benchmark evolved over the course
of GCC 10 development cycle, the first and biggest regression (9%)
comes with:
commit 2925cad2151842daa387950e62d989090e47c91d
Author: Jan Hubicka <hubi...@ucw.cz>
Date: Thu Oct 3 17:08:21 2019 +0200
params.def (PARAM_INLINE_HEURISTICS_HINT_PERCENT, [...]): New.
* params.def (PARAM_INLINE_HEURISTICS_HINT_PERCENT,
PARAM_INLINE_HEURISTICS_HINT_PERCENT_O2): New.
* doc/invoke.texi (inline-heuristics-hint-percent,
inline-heuristics-hint-percent-O2): Document.
* tree-inline.c (inline_insns_single, inline_insns_auto): Add new
hint attribute.
(can_inline_edge_by_limits_p): Use it.
From-SVN: r276516
Then between Wed Nov 6 (72d6aeecd95) and Mon Nov 18 (58c036c8354) it
improved to about 103% of GCC 9 run-time (I did not exactly found what
caused it because in much of this range the compiler was segfaulting
in the LTO phase). Eventually, the benchmark regresses to current
106% of GCC 9 run-time with Honza's:
- 9340d34599e Convert inliner to function specific param infrastructure, or
- 1e83bd7003e Convert inliner to new param infrastructure.
The former cannot be built without the latter.
Symbol profiles are:
trunk (26b3e568a60):
Overhead Samples Shared Object Symbol
........ ......... ....................
....................................
4.04% 42371 cpugcc_r_peak.pgolto bitmap_ior_into
2.91% 30281 cpugcc_r_peak.pgolto df_worklist_dataflow
2.24% 23342 cpugcc_r_peak.pgolto df_note_compute
1.92% 20120 cpugcc_r_peak.pgolto bitmap_set_bit
1.75% 18148 cpugcc_r_peak.pgolto rest_of_handle_fast_dce.lto_priv.0
1.58% 16580 libc-2.31.so __memset_avx2_unaligned_erms
1.40% 14514 cpugcc_r_peak.pgolto extract_new_fences_from.lto_priv.0
1.39% 14732 libc-2.31.so _int_malloc
1.33% 13824 cpugcc_r_peak.pgolto bitmap_copy
1.24% 12962 cpugcc_r_peak.pgolto bitmap_bit_p
1.19% 12346 cpugcc_r_peak.pgolto bitmap_and
1.18% 12242 cpugcc_r_peak.pgolto df_lr_local_compute.lto_priv.0
1.02% 10618 cpugcc_r_peak.pgolto cleanup_cfg.isra.0
vs gcc 9 (releases/gcc-9.3.0):
Overhead Samples Shared Object Symbol
........ ......... ....................
.....................................
6.81% 66967 cpugcc_r_peak.pgolto df_worklist_dataflow
2.83% 28063 cpugcc_r_peak.pgolto bitmap_ior_into
2.80% 27489 cpugcc_r_peak.pgolto df_note_compute.lto_priv.0
2.17% 21334 cpugcc_r_peak.pgolto rest_of_handle_fast_dce.lto_priv.0
1.69% 16671 libc-2.31.so __memset_avx2_unaligned_erms
1.51% 14876 cpugcc_r_peak.pgolto try_optimize_cfg.lto_priv.0
1.50% 14990 libc-2.31.so _int_malloc
1.50% 14715 cpugcc_r_peak.pgolto extract_new_fences_from.lto_priv.0
1.36% 13406 cpugcc_r_peak.pgolto df_lr_local_compute.lto_priv.0
1.20% 11926 cpugcc_r_peak.pgolto remove_unused_locals
1.06% 10433 cpugcc_r_peak.pgolto sched_analyze_insn
1.04% 10210 cpugcc_r_peak.pgolto init_alias_analysis
1.04% 10188 cpugcc_r_peak.pgolto prescan_insns_for_dce.lto_priv.0
1.00% 9876 cpugcc_r_peak.pgolto compute_transp
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)
