This showed up on i686-linux with BOOT_CFLAGS='-Os -g'. I didn't investigate the full call chain for why the variable wasn't set in the by-reference call to fortran_common.
r~
* dwarf2out.c (gen_variable_die): Initialize off. diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index 828e996..ca88fc5 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -17765,7 +17765,7 @@ common_block_die_table_eq (const void *x, const void *y) static void gen_variable_die (tree decl, tree origin, dw_die_ref context_die) { - HOST_WIDE_INT off; + HOST_WIDE_INT off = 0; tree com_decl; tree decl_or_origin = decl ? decl : origin; tree ultimate_origin;