[PATCH] gas: improve reproducibility for stabs debugging data format

[Denys Zagorui]

powerpc 32bit Linux Kernel widely uses .stabs pseudo-op to
produce debugging information in stabs format. Faced an issue
that during Linux Kernel build with Yocto build system for 32bit
powerpc platform resulting vmlinux contains absolute path in
.stabstr section that cannot be remapped with -fdebug-prefix-map
option.

Yocto uses scripts/mkmakefile Linux Kernel build approach that
allows to store all generated files outside of kernel source
tree. With this approach each compilier invocation is performed
with an absolute path to a file that will be compiled and this
absolute path is recorded in init stab. There is no way to remap
this path.

Reuse remap_debug_filename api to make -fdebug-prefix-map flag
aplicable for init stab.

2020-11-21  Denys Zagorui  <dzagorui@cisco.com>  (tiny change)

	* config/obj-elf (obj_elf_init_stab_section): Improve
	reproducibility for stabs debugging data format

Signed-off-by: Denys Zagorui <dzagorui@cisco.com>
---
 gas/ChangeLog        | 5 +++++
 gas/config/obj-elf.c | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 3c2d6891dc..8db46458df 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2020-11-21  Denys Zagorui  <dzagorui@cisco.com>  (tiny change)
+
+	* config/obj-elf (obj_elf_init_stab_section): Improve
+	reproducibility for stabs debugging data format
+
 2020-11-03  Christian Eggers  <ceggers@gmx.de>
 
 	* config/obj-elf (elf_frob_symbol): Fix symbol value calculation
diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
index 93eb81e98a..7aed8129bc 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -2425,12 +2425,13 @@ obj_elf_init_stab_section (segT seg)
   p = frag_more (12);
   /* Zero it out.  */
   memset (p, 0, 12);
-  file = as_where (NULL);
+  file = remap_debug_filename (as_where (NULL));
   stabstr_name = concat (segment_name (seg), "str", (char *) NULL);
   stroff = get_stab_string_offset (file, stabstr_name, TRUE);
   know (stroff == 1 || (stroff == 0 && file[0] == '\0'));
   md_number_to_chars (p, stroff, 4);
   seg_info (seg)->stabu.p = p;
+  xfree ((char *) file);
 }
 
 #endif
-- 
2.23.1