[Bug lto/65252] New: Link time optimization breaks use of filenames in linker scripts

[goswin-v-b at web dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65252

            Bug ID: 65252
           Summary: Link time optimization breaks use of filenames in
                    linker scripts
           Product: gcc
           Version: 4.8.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: goswin-v-b at web dot de
                CC: goswin-v-b at web dot de
              Host: x86_64-linux-gnu
            Target: x86_64-linux-gnu
             Build: arm-none-eabi

I'm building a kernel for a Rapsberry Pi 2 with -flto. Most of the code will be
linked to 0x8000xxxx. The kernel image will be loaded to 0x8000 and I have set
up LMA and VMA in my linker script accordingly. But I have some bootstrap code
(boot.S and early.cc) that needs to at the physical address. So I put the
following in my linker script:

ENTRY(_start)
PHYS_TO_VIRT = 0x80000000;
SECTIONS
{
    . = 0x8000;
    .early : {
        boot.o(.*)
        early.o(.*)
    }

    /* rest of the code runs in higher half virtual address */
    . = . + PHYS_TO_VIRT;
    .text : AT(ADDR(.text) - PHYS_TO_VIRT) {
    ...

Using objdump -d I see the boot.o contents show up at 0x8000 exactly as it
should. But all the code from early.o only appears later in the .text section
and at the virtual adress. If I drop the -flto then everything works as
expected. It would be nice if -flto could preserve which file each function and
variable comes from so the linker can place them properly.