[Bug ipa/65076] [5 Regression] 16% tramp3d-v4.cpp compile time regression

["trippels at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65076

--- Comment #5 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Perf shows:

Overhead  Command   Shared Object               Symbol
   2.45%  cc1plus   libc-2.21.90.so             [.] _int_malloc
   1.88%  cc1plus   cc1plus                     [.] bitmap_find_bit
   1.72%  cc1plus   cc1plus                     [.] gt_ggc_mx_lang_tree_node
   1.36%  cc1plus   libc-2.21.90.so             [.] _int_free
   1.05%  cc1plus   cc1plus                     [.] ggc_set_mark
   0.97%  cc1plus   cc1plus                     [.] record_reg_classes
   0.96%  cc1plus   cc1plus                     [.] df_worklist_dataflow
   0.91%  cc1plus   cc1plus                     [.] build_qualified_type
   0.88%  cc1plus   cc1plus                     [.] df_note_compute
   0.84%  cc1plus   libc-2.21.90.so             [.] malloc_consolidate

(Using a faster malloc implementation speeds up compile time by ~5%:

markus@x4 ~ % time g++ -w -Ofast tramp3d-v4.cpp
g++ -w -Ofast tramp3d-v4.cpp  26.00s user 0.32s system 99% cpu 26.341 total
markus@x4 ~ % time LD_PRELOAD=/usr/lib/libllalloc.so.1.3 g++ -w -Ofast
tramp3d-v4.cpp
LD_PRELOAD=/usr/lib/libllalloc.so.1.3 g++ -w -Ofast tramp3d-v4.cpp  24.60s user
0.37s system 99% cpu 24.997 total)