Just curious, what is the base line size of your comparison? Did you turn on GC (-ffunction-sections -fdata-sections -Wl,--gc-sections)?
David On Wed, Apr 28, 2010 at 2:44 AM, Bingfeng Mei <b...@broadcom.com> wrote: > Thanks, I will check what I can do with collect2. LTO > seems to save 6-9% code size for applications I tested > and should be very useful for us. > > Bingfeng > >> -----Original Message----- >> From: Richard Guenther [mailto:richard.guent...@gmail.com] >> Sent: 28 April 2010 10:33 >> To: Bingfeng Mei >> Cc: gcc@gcc.gnu.org >> Subject: Re: LTO question >> >> On Tue, Apr 27, 2010 at 6:30 PM, Bingfeng Mei >> <b...@broadcom.com> wrote: >> > Hello, >> > I have been playing with LTO. I notice that LTO doesn't work when >> > object files are achived into static library files and the final >> > binary is linked against them, although these object files >> are compiled >> > with -flto and I can see all the lto related sections in .a files. >> > Is this what is described in LTO Wiki page? >> > >> > "As an added feature, LTO will take advantage of the plugin feature >> > in gold. This allows the compiler to pick up object files that may >> > have been stored in library archives. " >> > >> > So do I have to use gold to solve this issue? >> >> Yes. Or you fix collect2 to do processing of archives and hand >> lto1 the required information (it expects archive components >> with LTO bytecode like archiv...@offset with offset being the >> offset of the .o file with LTO bytecode inside the archive). See >> lto/lto-elf.c:lto_obj_file_open for "details". >> >> Richard. >> >> > Many thanks, >> > Bingfeng >> > >> >> >
