This is the mail archive of the
gcc-help@gcc.gnu.org
mailing list for the GCC project.
optimizing costly calculation
- From: Mathieu Lacage <mathieu dot lacage at gmail dot com>
- To: gcc-help <gcc-help at gcc dot gnu dot org>
- Date: Tue, 3 Nov 2009 02:04:35 +0100
- Subject: optimizing costly calculation
hi,
I have a piece of code which does roughly this (after inlining):
Foo *foo1 = bar (ctx);
foo1->something ();
Foo *foo2 = bar (ctx);
foo2->something ();
bar is a function which will always return the same value if its input
is the same value (and ctx is constant over the function body) so, I
would like to instruct gcc that he can optimize away the second call
to bar but I could not find any obvious way to do this. Is this a
really stupid idea or did I miss something obvious ?
Mathieu
--
Mathieu Lacage <mathieu.lacage@gmail.com>