From: Jan Beulich <jbeulich@suse.com>
Date: Mon, 18 Nov 2024 10:36:30 +0000 (+0100)
Subject: ELF: SHF_MERGE vs SHT_NOBITS
X-Git-Tag: gdb-16-branchpoint~404
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=70ab7e0acfaf1cb32dfc184794e28408620a34f9;p=thirdparty%2Fbinutils-gdb.git

ELF: SHF_MERGE vs SHT_NOBITS

bfd/merge.c puts in quite some effort to track mergable sections. That's
all wasted for sections which don't have contents, as for them
_bfd_write_merged_section() will never be called.

With the combination not having any useful effect, also warn about this
in gas.
---

diff --git a/bfd/merge.c b/bfd/merge.c
index a4b928d9875..947f2ce78f2 100644
--- a/bfd/merge.c
+++ b/bfd/merge.c
@@ -627,6 +627,7 @@ _bfd_add_merge_section (bfd *abfd, void **psinfo, asection *sec,
 
   if (sec->size == 0
       || (sec->flags & SEC_EXCLUDE) != 0
+      || (sec->flags & SEC_HAS_CONTENTS) == 0
       || sec->entsize == 0)
     return true;
 
diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
index 4f09b8dc87c..deb902e5a55 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -1346,6 +1346,9 @@ obj_elf_section (int push)
 	      attr &= ~SHF_MERGE;
 	    }
 
+	  if ((attr & SHF_MERGE) != 0 && type == SHT_NOBITS)
+	    as_warn (_("bogus SHF_MERGE for SHT_NOBITS section"));
+
 	  if ((attr & SHF_LINK_ORDER) != 0 && *input_line_pointer == ',')
 	    {
 	      ++input_line_pointer;