performance regressions, profiling _of_ gcc

[Jan Van Dijk <janvandijkinjapan at yahoo dot co dot jp>]

	Hi,

In view of the recent compile time regressions in gcc versions I wanted to do 
some (detailed) profiling of gcc (mostly g++, I am particularly interested in 
the C++ front end). 

To this end I need more detailed information than -ftime-report gives me. 

I did some googling, but found no satisfactory links. For example, there was 
no response to message http://gcc.gnu.org/ml/gcc/1999-11n/msg00333.html.
The configuration docs ( http://gcc.gnu.org/install/configure.html ) briefly 
mention the --enable-coverage option. I read these and decided to configure 
gcc (HEAD) with 

	--enable-coverage=opt --disable-checking

and bootstrapped the compiler, but I am clueless how to proceed. I was 
assuming that running the new compiler on some test file would result in 
files suitable for analysis _of gcc_ with gcov/gprof, but nothing seems to 
appear.

Was I mistaken? Are there any other options? Is it possible to tell configure 
to simply add the extra cflag `-pg' to stages 2 and 3 of the compiler build? 
Should an external tool, like valgrind rather be used for performance 
analysis?

Pointers to (well-hidden :-) docs about profiling gcc are appreciated? If no 
such docs exist, brief instructions would be welcome, and I will try to 
contribute some documentation myself.

Thanks in advance,

	Jan van Dijk

-- 
Keio-Tsuushin Residence
Jan van Dijk, Room 210
2 Chome 19-30, Mita Minato-ku
108 Tokyo, Japan

jan at etpmod dot phys dot tue dot nl
tel: +81 3 5476 9461 (home)

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