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Re: Update LTO plugin interface
On Wed, Dec 1, 2010 at 10:54 AM, Ian Lance Taylor <iant@google.com> wrote:
> "H.J. Lu" <hjl.tools@gmail.com> writes:
>
>> ? ? ? b. Compiler plugin controls what linker uses to generate the final executable:
>> ? ? ? ? ? ? ? i. The linker command line order should be the same, with or without LTO.
>> ? ? ? c. Add a cmdline bit field to
>> ? ? ? struct ld_plugin_input_file
>> ? ? ? {
>> ? ? ? ? ?const char *name;
>> ? ? ? ? ?int fd;
>> ? ? ? ? ?off_t offset;
>> ? ? ? ? ?off_t filesize;
>> ? ? ? ? ?void *handle;
>> ? ? ? ? ?unsigned int cmdline : 1;
>> ? ? ? };
>
> Just make it an int. ?But I don't see why this is needed. ?The plugin
> already knows the files that it passed to add_input_file and
> add_input_library. ?Why does it need to linker to report back where the
> file came from? ?Why doesn't the plugin just keep track?
>
It is used to keep the same linker command line order. With LTO,
linker should use
crtX.o *trans*.o -lbar -lgcc -lc ... crtX.o
instead of
crtX.o -lbar -lgcc -lc ... crtX.o *trans*.o
to generate final executable. 2 orders may generate different
executables.
--
H.J.