[Bug pch/53880] [4.8 Regression] compile time regression when generating precompiled headers for boost

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53880

--- Comment #28 from Steven Bosscher <steven at gcc dot gnu.org> 2012-07-30 14:22:37 UTC ---
With -ftrack-macro-expansion=2 (the default):

(gdb) call dump_line_table_statistics()
Number of expanded macros:                     237994
Average number of tokens per macro expansion:     12

Line Table allocations during the compilation process
Number of ordinary maps used:         2732
Ordinary map used size:                106k
Number of ordinary maps allocated:    6553
Ordinary maps allocated size:          255k
Number of macro maps used:             183k
Macro maps used size:                 7339k
Macro maps locations size:              24M
Macro maps size:                        31M
Duplicated maps locations size:       5598k
Total allocated maps size:              40M
Total used maps size:                   31M


With -ftrack-macro-expansion=0:
(gdb) call dump_line_table_statistics()
Number of expanded macros:                     233678
Average number of tokens per macro expansion:     13

Line Table allocations during the compilation process
Number of ordinary maps used:         2732
Ordinary map used size:                106k
Number of ordinary maps allocated:    6553
Ordinary maps allocated size:          255k
Number of macro maps used:               0
Macro maps used size:                    0
Macro maps locations size:               0
Macro maps size:                         0
Duplicated maps locations size:          0
Total allocated maps size:             255k
Total used maps size:                  106k

(The count for number of tokens per macro expansion should be the same, looks
like a bug...).