Hi, On 08.Aug.2010, at 22:04, Andrew W. Steiner wrote:
> Thanks for your thoughts. My naive guess is > that It would be difficult, could be > if not impossible for the > optimizer to know this, as one could always > insert a call to an external function which > ostensibly initializes the variable but may or > may not fail to do so. Additionally, I > don't forsee any work on the C/C++ compilers > which guarantees that the optimizer will > accomplish this task, leaving it up to those > who write the source code to take care of it. However, the code you send is valid C and valid C++ (AFAICT). Therefore, a correct (C or C++) compiler must create valid machine code from it. It's that simple. > On Sun, Aug 8, 2010 at 3:28 PM, Jochen Küpper > <[email protected]> wrote: >> Isn't that an issue that should be handled by the optimizer? That's the >> instance that knows whether this issue might occur or not, i.e., it >> knows whether the variable is put into a register or not. >> >> Therefore, the optimizer should initialize this variable if it's put into a >> register (probably using a switch to turn off or on). Obviously, it then >> has to determine whether it is still worth the register usage with >> the added overhead of initialization. >> >> Or would it actually be feasible to use the register (for x) without >> moving the content of &x but instead using whatever happens to >> be in the register? >> Greetings, Jochen -- Einigkeit und Recht und Freiheit http://www.Jochen-Kuepper.de Liberté, Égalité, Fraternité GnuPG key: CC1B0B4D Sex, drugs and rock-n-roll _______________________________________________ Help-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-gsl
