On Thu, Apr 07, 2005 at 03:36:18PM -0700, James E Wilson wrote: > H. J. Lu wrote: > >Gcc 4,0 generates > >.section .gnu.linkonce.t._ZN3FooC1Ev,"axG",@progbits,_ZN3FooC1Ev,comdat > >for comdat group. Can gcc use > >.section .text._ZN3FooC1Ev,"axG",@progbits,_ZN3FooC1Ev,comdat > >instead? At least, there will be less characters for linker to process. > > I know of no reason why we must continue using .gnu.linkonce for targets > that have proper comdat support. > > However, I don't think this will be an easy transition, because there > are too many places that make assumptions about the fact that > .gnu.linkonce has a special meaning. That might be an argument against > even trying. > > For instance, in varasm.c, in default_function_rodata_section, we have > /* For .gnu.linkonce.t.foo we want to use .gnu.linkonce.r.foo. */ > if (DECL_ONE_ONLY (decl) && strncmp (name, ".gnu.linkonce.t.", > 16) == 0) > and this code fails if you remove the .gnu.linkonce from the section > name. We'd need code to check for and handle a comdat section here. > > dwarf2out.c assumes that comdat sections for debugging start with > .gnu.linkonce.
I am not sure if dwarf2out.c supports comdat group at all: http://gcc.gnu.org/ml/gcc-patches/2005-04/msg00711.html > > There are likely many other places that need fixing also. > > There is also the possible issue that using .text.foo conflicts with the > naming scheme used by the -ffunction-sections -fdata-sections options. > What happens if we have two sections both named .text.foo, one of which > is a comdat section, and one of which came from -ffunction-sections? We The assembler with proper comdat group should be OK. I had to fix the assembler to support dupulicated section names for comdat group. For linker, input section names are only used to group sections for output. > might still need to use a distinct prefix to make this work, though it > doesn't have to be as long as .gnu.linkonce. And if we do add another > prefix, some of the special code for .gnu.linkonce will have to be > duplicated, in which case it might have been simpler to just stick with > .gnu.linkonce in the first place. The current linker supports "--sort-section name". .text.foo is easier to deal with than .gnu.linkonce.t.foo when mixing comdat and non-comdat sections. H.J.
