strip: Don't treat fat IR objects as plugin object

Fat IR objects contains both regular sections and IR sections.  After

commit 717a38e9a0
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Sun May 4 05:12:46 2025 +0800

    strip: Add GCC LTO IR support

"strip --strip-debug" no longer strips debug sections in fat IR objects
since fat IR objects are recognized as plugin object and copied as unknown
objects.  Add a is_strip_input field to bfd to indicate called from strip.
Update bfd_check_format_matches not to treat archive member nor standalone
fat IR object as IR object so that strip can remove debug and IR sections
in fat IR object.  For archive member, it is copied as an unknown object
if the plugin target is in use or it is a slim IR object.  For standalone
fat IR object, it is copied as non-IR object.

bfd/

	PR binutils/33246
	* archive.c: Include "plugin-api.h" and "plugin.h" if plugin is
	enabled.
	(_bfd_compute_and_write_armap): Don't complain plugin is needed
	when the plugin target is in use.
	* bfd-in2.h: Regenerated.
	* bfd.c (bfd): Add is_strip_input.
	* format.c (bfd_set_lto_type): If there is .llvm.lto section,
	set LTO type to lto_fat_ir_object.
	(bfd_check_format_matches): Don't set LTO type when setting
	format.  When called from strip, don't treat archive member nor
	standalone fat IR object as an IR object.
	* plugin.c (bfd_plugin_get_symbols_in_object_only): Copy LTO
	type derived from input sections.

nm/

	PR binutils/33246
	* nm.c (filter_symbols): Don't complain plugin is needed when
	the plugin target is in use.
	(display_rel_file): Likewise.
	* objcopy.c (copy_archive): Set the BFD is_strip_input field of
	archive member to 1 to indicate called from strip.  Also copy
	slim IR archive member as unknown object.
	(copy_file): Set the BFD is_strip_input field of input bfd to
	1 to indicate called from strip.
	(strip_main): Keep .gnu.debuglto_* sections unless all GCC LTO
	sections will be removed.

ld/

	PR binutils/33246
	* testsuite/ld-plugin/lto-binutils.exp (run_pr33246_test): New.
	Run binutils/33246 tests with GCC and Clang.
	* testsuite/ld-plugin/pr33246.c: New file.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

bfd/archive.c

@@ -141,6 +141,10 @@ SUBSECTION
 #include "hashtab.h"
 #include "filenames.h"
 #include "bfdlink.h"
+#if BFD_SUPPORTS_PLUGINS
+#include "plugin-api.h"
+#include "plugin.h"
+#endif
 
 #ifndef errno
 extern int errno;
@@ -2343,6 +2347,9 @@ _bfd_compute_and_write_armap (bfd *arch, unsigned int elength)
 	  long src_count;
 
 	  if (bfd_get_lto_type (current) == lto_slim_ir_object
+#if BFD_SUPPORTS_PLUGINS
+	      && !bfd_plugin_target_p (current->xvec)
+#endif
 	      && report_plugin_err)
 	    {
 	      report_plugin_err = false;
@@ -2400,6 +2407,9 @@ _bfd_compute_and_write_armap (bfd *arch, unsigned int elength)
 
 		      if (bfd_lto_slim_symbol_p (current,
 						 syms[src_count]->name)
+#if BFD_SUPPORTS_PLUGINS
+			  && !bfd_plugin_target_p (current->xvec)
+#endif
 			  && report_plugin_err)
 			{
 			  report_plugin_err = false;

bfd/bfd-in2.h

@@ -2131,6 +2131,9 @@ struct bfd
   /* Set if this is the linker input BFD.  */
   unsigned int is_linker_input : 1;
 
+  /* Set if this is the strip input BFD.  */
+  unsigned int is_strip_input : 1;
+
   /* If this is an input for a compiler plug-in library.  */
   ENUM_BITFIELD (bfd_plugin_format) plugin_format : 2;
 

bfd/bfd.c

@@ -296,6 +296,9 @@ CODE_FRAGMENT
 .  {* Set if this is the linker input BFD.  *}
 .  unsigned int is_linker_input : 1;
 .
+.  {* Set if this is the strip input BFD.  *}
+.  unsigned int is_strip_input : 1;
+.
 .  {* If this is an input for a compiler plug-in library.  *}
 .  ENUM_BITFIELD (bfd_plugin_format) plugin_format : 2;
 .

bfd/format.c

@@ -389,6 +389,11 @@ bfd_set_lto_type (bfd *abfd ATTRIBUTE_UNUSED)
 	    abfd->object_only_section = sec;
 	    break;
 	  }
+	else if (strcmp (sec->name, ".llvm.lto") == 0)
+	  {
+	    type = lto_fat_ir_object;
+	    break;
+	  }
 	else if (lsection.major_version == 0
 		 && startswith (sec->name, ".gnu.lto_.lto.")
 		 && bfd_get_section_contents (abfd, sec, &lsection, 0,
@@ -453,10 +458,7 @@ bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
     }
 
   if (abfd->format != bfd_unknown)
-    {
-      bfd_set_lto_type (abfd);
     return abfd->format == format;
-    }
 
   if (matching != NULL || *bfd_associated_vector != NULL)
     {
@@ -510,7 +512,20 @@ bfd_check_format_matches (bfd *abfd, bfd_format format, char ***matching)
 
       cleanup = BFD_SEND_FMT (abfd, _bfd_check_format, (abfd));
 
-      if (cleanup)
+      /* When called from strip, don't treat archive member nor
+	 standalone fat IR object as an IR object.  For archive
+	 member, it will be copied as an unknown object if the
+	 plugin target is in use or it is a slim IR object.  For
+	 standalone fat IR object, it will be copied as non-IR
+	 object.  */
+      if (cleanup
+#if BFD_SUPPORTS_PLUGINS
+	  && (!abfd->is_strip_input
+	      || !bfd_plugin_target_p (abfd->xvec)
+	      || (abfd->lto_type != lto_fat_ir_object
+		  && abfd->my_archive == NULL))
+#endif
+	  )
 	goto ok_ret;
 
       /* For a long time the code has dropped through to check all

bfd/plugin.c

@@ -206,6 +206,9 @@ bfd_plugin_get_symbols_in_object_only (bfd *abfd)
 	  bfd_close (nbfd);
 	  return;
 	}
+
+      /* Copy LTO type derived from input sections.  */
+      abfd->lto_type = nbfd->lto_type;
     }
   else
     {

binutils/nm.c

@@ -802,6 +802,9 @@ filter_symbols (bfd *abfd, bool is_dynamic, void *minisyms,
 	continue;
 
       if (bfd_lto_slim_symbol_p (abfd, sym->name)
+#if BFD_SUPPORTS_PLUGINS
+	  && !bfd_plugin_target_p (abfd->xvec)
+#endif
 	  && report_plugin_err)
 	{
 	  report_plugin_err = false;
@@ -1484,7 +1487,11 @@ display_rel_file (bfd *abfd, bfd *archive_bfd)
 
   /* lto_type is set to lto_non_ir_object when a bfd is loaded with a
      compiler LTO plugin.  */
-  if (bfd_get_lto_type (abfd) == lto_slim_ir_object)
+  if (bfd_get_lto_type (abfd) == lto_slim_ir_object
+#if BFD_SUPPORTS_PLUGINS
+      && !bfd_plugin_target_p (abfd->xvec)
+#endif
+     )
     {
       report_plugin_err = false;
       non_fatal (_("%s: plugin needed to handle lto object"),

binutils/objcopy.c

@@ -3689,6 +3689,8 @@ copy_archive (bfd *ibfd, bfd *obfd, const char *output_target,
       bool ok_object;
       const char *element_name;
 
+      this_element->is_strip_input = 1;
+
       element_name = bfd_get_filename (this_element);
       /* PR binutils/17533: Do not allow directory traversal
 	 outside of the current directory tree by archive members.  */
@@ -3769,7 +3771,9 @@ copy_archive (bfd *ibfd, bfd *obfd, const char *output_target,
 
 #if BFD_SUPPORTS_PLUGINS
       /* Copy LTO IR file as unknown object.  */
-      if (bfd_plugin_target_p (this_element->xvec))
+      if ((!lto_sections_removed
+	   && this_element->lto_type == lto_slim_ir_object)
+	  || bfd_plugin_target_p (this_element->xvec))
 	ok_object = false;
       else
 #endif
@@ -3966,6 +3970,8 @@ copy_file (const char *input_filename, const char *output_filename, int ofd,
       break;
     }
 
+  ibfd->is_strip_input = 1;
+
   if (bfd_check_format (ibfd, bfd_archive))
     {
       bool force_output_target;
@@ -5072,6 +5078,11 @@ strip_main (int argc, char *argv[])
 					       SECTION_CONTEXT_REMOVE)
 			  || !!find_section_list (".llvm.lto", false,
 					       SECTION_CONTEXT_REMOVE));
+  /* NB: Must keep .gnu.debuglto_* sections unless all GCC LTO sections
+     will be removed to avoid undefined references to symbols in GCC LTO
+     debug sections.  */
+  if (!lto_sections_removed)
+    find_section_list (".gnu.debuglto_*", true, SECTION_CONTEXT_KEEP);
 #endif
 
   i = optind;

ld/testsuite/ld-plugin/lto-binutils.exp

@@ -355,3 +355,178 @@ run_cc_link_tests [list \
 	"tmpdir/libstrip-1b-fat-s.a" \
     ] \
 ]
+
+proc run_pr33246_test { llvm fat } {
+    global srcdir
+    global subdir
+    global plug_opt
+    global llvm_plug_opt
+    global ar
+    global CLANG_FOR_TARGET
+    global CC_FOR_TARGET
+    global NM
+    global READELF
+    global strip
+
+    set strip_flags "--strip-debug --enable-deterministic-archives"
+
+    set test pr33246
+    set testname "${test}${llvm}${fat} with $strip_flags"
+
+    if { "$llvm" == "-llvm" } {
+	# Skip native x32 and i?86 targets since system LLVMgold.so may
+	# not be compatible with native x32 and i?86 targets binutils.
+	if { [istarget "x86_64-*-linux*-gnux32"]
+	     || [istarget "i?86-*-*"]
+	     || ![info exists CLANG_FOR_TARGET]
+	     || [string match "" $llvm_plug_opt] } then {
+	    untested $testname
+	    return
+	}
+	set CC $CLANG_FOR_TARGET
+	set binutils_plug_opt "$llvm_plug_opt"
+    } else {
+	if { ![info exists CC_FOR_TARGET]
+	     || [string match "" $plug_opt] } then {
+	    untested $testname
+	    return
+	}
+	set CC $CC_FOR_TARGET
+	set binutils_plug_opt "$plug_opt"
+    }
+
+    append strip_flags " $binutils_plug_opt"
+
+    set src $srcdir/$subdir/${test}.c
+    set obj tmpdir/${test}${llvm}${fat}.o
+    set archive tmpdir/${test}${llvm}${fat}.a
+    set CFLAGS "-c -g -O2 -flto"
+    if { "$fat" == "-fat" } {
+	append CFLAGS " -ffat-lto-objects"
+    } else {
+	append CFLAGS " -fno-fat-lto-objects"
+    }
+
+    set cmd "$CC $CFLAGS -o $obj $src"
+    send_log "$cmd\n"
+    verbose "$cmd" 1
+    catch "exec $cmd" got
+    if ![string match "" $got] then {
+	send_log "$got\n"
+	verbose "$got" 1
+	fail "$testname ($obj)"
+	return
+    }
+
+    set cmd "$strip $strip_flags $obj -o ${obj}.strip"
+    send_log "$cmd\n"
+    verbose "$cmd" 1
+    catch "exec $cmd" got
+    if ![string match "" $got] then {
+	send_log "$got\n"
+	verbose "$got" 1
+	fail "$testname (strip $obj)"
+	return
+    }
+
+    set cmd "$NM $binutils_plug_opt ${obj}.strip"
+    send_log "$cmd\n"
+    verbose "$cmd" 1
+    catch "exec $cmd" got
+    if ![regexp "0+ T foo" $got] then {
+	send_log "$got\n"
+	verbose "$got" 1
+	fail "$testname (strip $obj)"
+	return
+    }
+
+    if { "$fat" == "-fat" } {
+	set cmd "$READELF -SW ${obj}.strip"
+	send_log "$cmd\n"
+	verbose "$cmd" 1
+	catch "exec $cmd" got
+	if [regexp " \.debug_" $got] then {
+	    send_log "$got\n"
+	    verbose "$got" 1
+	    fail "$testname (strip $obj)"
+	    return
+	}
+    } else {
+	set cmd "cmp $obj ${obj}.strip"
+	send_log "$cmd\n"
+	verbose "$cmd" 1
+	catch "exec $cmd" got
+	if ![string match "" $got] then {
+	    send_log "$got\n"
+	    verbose "$got" 1
+	    fail "$testname (strip $obj)"
+	    return
+	}
+    }
+
+    pass "$testname (strip $obj)"
+
+    set cmd "$ar $binutils_plug_opt -D -s -r -c $archive $obj"
+    send_log "$cmd\n"
+    verbose "$cmd" 1
+    catch "exec $cmd" got
+    if ![string match "" $got] then {
+	send_log "$got\n"
+	verbose "$got" 1
+	fail "$testname ($archive)"
+	return
+    }
+
+    set cmd "$strip $strip_flags $archive -o ${archive}.strip"
+    send_log "$cmd\n"
+    verbose "$cmd" 1
+    catch "exec $cmd" got
+    if ![string match "" $got] then {
+	send_log "$got\n"
+	verbose "$got" 1
+	fail "$testname (strip $archive)"
+	return
+    }
+
+    set cmd "$NM $binutils_plug_opt ${archive}.strip"
+    send_log "$cmd\n"
+    verbose "$cmd" 1
+    catch "exec $cmd" got
+    if ![regexp "0+ T foo" $got] then {
+	send_log "$got\n"
+	verbose "$got" 1
+	fail "$testname (strip $archive)"
+	return
+    }
+
+    if { "$fat" == "-fat" } {
+	set cmd "$READELF -SW ${archive}.strip"
+	send_log "$cmd\n"
+	verbose "$cmd" 1
+	catch "exec $cmd" got
+	if [regexp " \.debug_" $got] then {
+	    send_log "$got\n"
+	    verbose "$got" 1
+	    fail "$testname (strip $archive)"
+	    return
+	}
+    } else {
+	set cmd "cmp $archive ${archive}.strip"
+	send_log "$cmd\n"
+	verbose "$cmd" 1
+	catch "exec $cmd" got
+	if ![string match "" $got] then {
+	    send_log "$got\n"
+	    verbose "$got" 1
+	    fail "$testname (strip $archive)"
+	    return
+	}
+    }
+
+    pass "$testname (strip $archive)"
+}
+
+run_pr33246_test "" ""
+run_pr33246_test "" "-fat"
+run_pr33246_test "-llvm" ""
+run_pr33246_test "-llvm" "-fat"

ld/testsuite/ld-plugin/pr33246.c

@@ -0,0 +1,4 @@
+void
+foo (void)
+{
+}