https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77839
Bug ID: 77839
Summary: [7 Regression] Memory- and compile time hog at -O1 and
above
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Keywords: compile-time-hog, memory-hog
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: asolokha at gmx dot com
Target Milestone: ---
Current gcc 7 snapshots (and also as old as 7.0.0-alpha20160731) hog time and
memory when compiling the following reduced snippet at -O1 (or higher):
void
sd(int yn)
{
while (yn < 1)
{
int hy;
int *n6 = &hy;
int **ot = &n6;
(void)ot;
for (yn = 0; yn < 1; ++yn)
{
int tc, wo = 0, ez = 0, b8 = 0;
int *ls = &wo;
(void)ls;
hy = 0;
for (tc = 0; tc < 1; ++tc)
{
ez ^= hy;
wo ^= ez;
++b8;
}
hy += (b8 < wo);
}
}
}
% timeout 20 gcc-7.0.0-alpha20161002 -O1 -c v5ydrl0g.c
zsh: exit 124
Several top entries reported by perf:
4.32% cc1 cc1 [.] visit_use
1.79% cc1 cc1 [.] mark_used_flags
1.50% cc1 cc1 [.] walk_tree_1
1.36% cc1 cc1 [.] VN_INFO
1.30% cc1 cc1 [.] operand_equal_p
1.14% cc1 libc-2.23.so [.] _int_malloc
1.09% cc1 libc-2.23.so [.] __memset_sse2
1.07% cc1 cc1 [.] inchash::add_expr
0.94% cc1 cc1 [.] vn_reference_eq
0.91% cc1 cc1 [.]
iterative_hash_host_wide_int
0.83% cc1 cc1 [.]
copy_reference_ops_from_ref
0.82% cc1 cc1 [.] set_ssa_val_to
0.82% cc1 cc1 [.]
hash_table<vn_phi_hasher, xcallocator>::find_slot_with_hash
0.80% cc1 cc1 [.]
iterative_hash_hashval_t
0.80% cc1 cc1 [.] tree_operand_check
0.78% cc1 cc1 [.] wide_int_to_tree
0.75% cc1 cc1 [.]
hash_table<vn_reference_hasher, xcallocator>::find_slot_with_hash
0.75% cc1 cc1 [.] ggc_internal_alloc
0.73% cc1 cc1 [.] walk_gimple_op
0.73% cc1 libc-2.23.so [.] _int_free
0.71% cc1 cc1 [.] valueize_refs_1
0.70% cc1 cc1 [.] get_ref_base_and_extent
0.68% cc1 cc1 [.]
vn_reference_compute_hash
0.66% cc1 cc1 [.] bitmap_set_bit
0.64% cc1 cc1 [.] vn_phi_compute_hash
0.63% cc1 libc-2.23.so [.] __memset_avx2
0.63% cc1 cc1 [.]
df_live_bb_local_compute
0.59% cc1 cc1 [.] is_gimple_reg
0.54% cc1 cc1 [.] gimple_simplify
0.53% cc1 cc1 [.] get_alias_set
0.52% cc1 cc1 [.]
gimple_fold_stmt_to_constant_1
0.51% cc1 cc1 [.] is_gimple_val
