On Mon, Dec 07, 2009 at 05:47:13PM -0800, Joe Perches wrote:
> On Tue, 2009-12-08 at 00:57 +0000, Anton Altaparmakov wrote:
> > Can you please explain the rational for making this change?
>
> Perhaps it's not worth much, but it saves a pointer reference.
>
> $ cat pointer.c
> #include <string.h>
> #include <stdio.h>
>
> int main (int argc, char** argv)
> {
> static const char *foo = "abcdefg";
> printf("%s\n", foo);
> return 0;
> }
>
> $ gcc -c pointer.c
> $ size pointer.o
> text data bss dec hex filename
> 37 4 0 41 29 pointer.o
>
> $ cat reference.c
> #include <string.h>
> #include <stdio.h>
>
> int main (int argc, char** argv)
> {
> static const char foo[] = "abcdefg";
> printf("%s\n", foo);
> return 0;
> }
>
> $ gcc -c reference.c
> $ size reference.o
> text data bss dec hex filename
> 36 0 0 36 24 reference.o
Yeah, for static variables it's better. But for automatic variables
it's worse, because it now has to do a copy at runtime.
And the patch changes both types.
$ size pointer.o reference.o
text data bss dec hex filename
101 8 0 109 6d pointer.o
96 0 0 96 60 reference.o
$ size pointer-nonstatic.o reference-nonstatic.o
text data bss dec hex filename
106 0 0 106 6a pointer-nonstatic.o
109 0 0 109 6d reference-nonstatic.o
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