The attached code (a md4 function, about 100 lines) takes many minutes
(apparently >100) to compile with gcc mainline 4.3 at -O3. At -O2, or with gcc
4.2, it takes below 1 second. 4.3.0 20070411 is OK, too. Memory requirement
stays very low.
The top of a profile with mainline looks like this:
% symbol name
14.8255 iterative_hash_expr
14.5251 bitmap_find_leader
13.8068 phi_translate
7.3317 iterative_hash
6.5265 get_value_handle
5.3315 htab_find_slot_with_hash
5.0914 iterative_hash_pointer
3.8050 iterative_hash_hashval_t
3.4260 bitmap_set_contains_value
2.3798 is_gimple_min_invariant
2.2232 iterative_hash_host_wide_int
2.0325 tree_operand_length
1.8615 translate_vuses_through_block
1.7766 bitmap_bit_p
1.6062 find_leader_in_sets
1.5111 expression_for_id
1.3981 vn_compute
1.2290 tree_operand_length
1.0592 expr_pred_trans_eq
--
Summary: Short function (md4) takes very long to compile
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Keywords: compile-time-hog
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: falk at debian dot org
GCC build triplet: alphaev68-unknown-linux-gnu
GCC host triplet: alphaev68-unknown-linux-gnu
GCC target triplet: alphaev68-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31911
