--- Begin Message ---
|
Subject: |
[Bug c++/14563] octave built under Cygwin very slow |
|
Date: |
25 Mar 2004 14:37:03 -0000 |
------- Additional Comments From bangerth at dealii dot org 2004-03-25 14:36
-------
SJLJ stands for "setjmp/longjmp". I'm not an expert in this field
(as I know virtually nothing about the gcc interiors anyway, I'm
just the bug database dude), but here's the idea: when you call
a function that may or may not throw an exception, and the calling
function needs to run destructors of local objects in case an exception
is thrown, you need to put down the address of the cleanup code somewhere.
One way to do this is to set this address via setjmp, and throwing an
exception then transfers control to this place via longjmp. This is expensive
since you have to call setjmp every time a cleanup is necessary.
The other possibility is to use lookup tables that the compiler generates
statically, so this is cheap at run-time, but incurs some code overhead. If
you generate an exception, you have to somehow look up where to transfer
execution. Don't ask me how exactly this works, but it is to my best
knowledge how dwarf2 exception unwinding works. Corrections on this topic
my more knowledgable people are certainly welcome.
Now back to the question how we can figure out what the problem is: if
using -fno-exceptions doesn't work, is there a possibility you repeat
your experiments with an octave version prior to the introduction of
exceptions?
W.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14563
------- You are receiving this mail because: -------
You reported the bug, or are watching the reporter.
--- End Message ---