[Bug debug/101987] New: gcc 10.3.1 fails to generate debugging information for aarch64 .S files

[dcmay at copper dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101987

            Bug ID: 101987
           Summary: gcc 10.3.1 fails to generate debugging information for
                    aarch64 .S files
           Product: gcc
           Version: 10.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcmay at copper dot net
  Target Milestone: ---

Created attachment 51325
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51325&action=edit
simple makefile project

Using the ARM / linaro aarch64-none-elf build of gcc 10.3.1, building a bare
metal bootloader, (at least) the boot.S entry code is missing all debugging
information. As such, gdb fails to step or honor breakpoints in the startup
code.

linaro's 10.2.1 version generates debugging information as expected; and the
same file compiled with the Ubuntu 20.04 gcc-10.3.0 aarch64 cross compiler
matches exactly (except for AS version number), when viewed using objdump -W.

The problem is trivially reproduced using the attached project, which builds
with missing debug info in target/boot.o using linaro's 10.3.1 cross compiler.