[PATCH] strip: Treat slim GCC/LLVM IR objects the same

[H.J. Lu]

Slim LLVM IR object is a standalone file whose first 4 bytes are 'B',
'C', 0xc0, 0xde.  GCC IR object is regular ELF object with sections
whose names start with .gnu.lto_.* or .gnu.debuglto_.*.  GCC IR object
uses a .gnu.lto_.lto.<some_hash> section to encode the LTO bytecode
information:

struct lto_section
{
  int16_t major_version;
  int16_t minor_version;
  unsigned char slim_object;

  /* Flags is a private field that is not defined publicly.  */
  uint16_t flags;
};

In slim GCC IR object, the slim_object field is non-zero.  Strip should
treat slim GCC/LLVM IR objects the same.  Since strip won't change slim
LLVM IR objects, it should leave slim GCC IR object unchanged even when
asked to remove all IR objects:

1. Set the lto_type field to lto_slim_ir_object for slim LLVM IR object.
2. Always copy slim IR object as unknown object.

bfd/

	PR binutils/33271
	* plugin.c (bfd_plugin_object_p): Set the lto_type field to
	lto_slim_ir_object for slim LLVM IR object.

binutils/

	PR binutils/33271
	* objcopy.c (copy_archive): Always copy slim IR object as unknown
	object.
	(copy_file): Likewise.

ld/

	PR binutils/33271
	* testsuite/ld-plugin/lto-binutils.exp: Don't check if fat IR is
	available when running slim IR tests.
	* testsuite/ld-plugin/strip-1a-s-all.nd: Expect full symbol list.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
 bfd/plugin.c                             | 19 ++++++++++++-
 binutils/objcopy.c                       | 10 +++----
 ld/testsuite/ld-plugin/lto-binutils.exp  | 34 +++++++++++-------------
 ld/testsuite/ld-plugin/strip-1a-s-all.nd |  5 +++-
 4 files changed, 42 insertions(+), 26 deletions(-)

diff --git a/bfd/plugin.c b/bfd/plugin.c
index 733e7f0f322..19f2c8ae534 100644
--- a/bfd/plugin.c
+++ b/bfd/plugin.c
@@ -772,7 +772,24 @@ bfd_plugin_object_p (bfd *abfd)
   if (abfd->plugin_format == bfd_plugin_unknown && !load_plugin (abfd))
     return NULL;
 
-  return abfd->plugin_format == bfd_plugin_yes ? _bfd_no_cleanup : NULL;
+  if (abfd->plugin_format == bfd_plugin_yes)
+    {
+      /* Check slim LLVM IR object whose first 4 bytes: 'B', 'C', 0xc0,
+	 0xde.  */
+      bfd_byte llvm_ir_magic[4];
+      if (abfd->lto_type == lto_non_object
+	  && bfd_seek (abfd, 0, SEEK_SET) == 0
+	  && bfd_read (llvm_ir_magic, 4, abfd) == 4
+	  && llvm_ir_magic[0] == 'B'
+	  && llvm_ir_magic[1] == 'C'
+	  && llvm_ir_magic[2] == 0xc0
+	  && llvm_ir_magic[3] == 0xde)
+	abfd->lto_type = lto_slim_ir_object;
+
+      return _bfd_no_cleanup;
+    }
+  else
+    return NULL;
 }
 
 /* Copy any private info we understand from the input bfd
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index 654d2b9b44a..d53f085c1c7 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -3771,10 +3771,8 @@ copy_archive (bfd *ibfd, bfd *obfd, const char *output_target,
 	}
 
 #if BFD_SUPPORTS_PLUGINS
-      /* Copy LTO IR file as unknown object.  */
-      if ((!lto_sections_removed
-	   && this_element->lto_type == lto_slim_ir_object)
-	  || bfd_plugin_target_p (this_element->xvec))
+      /* Copy slim LTO IR file as unknown object.  */
+      if (this_element->lto_type == lto_slim_ir_object)
 	ok_object = false;
       else
 #endif
@@ -4042,9 +4040,9 @@ copy_file (const char *input_filename, const char *output_filename, int ofd,
  	}
 
 #if BFD_SUPPORTS_PLUGINS
-      if (bfd_plugin_target_p (ibfd->xvec))
+      if (ibfd->lto_type == lto_slim_ir_object)
 	{
-	  /* Copy LTO IR file as unknown file.  */
+	  /* Copy slim LTO IR file as unknown file.  */
 	  if (!copy_unknown_file (ibfd, obfd, in_stat->st_size,
 				  in_stat->st_mode))
 	    status = 1;
diff --git a/ld/testsuite/ld-plugin/lto-binutils.exp b/ld/testsuite/ld-plugin/lto-binutils.exp
index 4970e2282cb..1e156e4fc78 100644
--- a/ld/testsuite/ld-plugin/lto-binutils.exp
+++ b/ld/testsuite/ld-plugin/lto-binutils.exp
@@ -254,24 +254,22 @@ run_lto_binutils_test [list \
     ] \
 ]
 
-if { [check_lto_fat_available] } {
-    run_lto_binutils_test [list \
-	[list \
-	    "strip" \
-	    "-R .gnu.*lto_* -N __gnu_lto_v1" \
-	    "strip-1a.o" \
-	    "strip-1a-s-all.o" \
-	    {{nm -n strip-1a-s-all.nd}} \
-	] \
-	[list \
-	    "strip" \
-	    "-R .gnu.*lto_* -N __gnu_lto_v1" \
-	    "libstrip-1a.a" \
-	    "libstrip-1a-s-all.a" \
-	    {{nm -n strip-1a-s-all.nd}} \
-	] \
-    ]
-}
+run_lto_binutils_test [list \
+    [list \
+	"strip" \
+	"-R .gnu.*lto_* -N __gnu_lto_v1" \
+	"strip-1a.o" \
+	"strip-1a-s-all.o" \
+	{{nm -n strip-1a-s-all.nd}} \
+    ] \
+    [list \
+	"strip" \
+	"-R .gnu.*lto_* -N __gnu_lto_v1" \
+	"libstrip-1a.a" \
+	"libstrip-1a-s-all.a" \
+	{{nm -n strip-1a-s-all.nd}} \
+    ] \
+]
 
 run_cc_link_tests [list \
     [list \
diff --git a/ld/testsuite/ld-plugin/strip-1a-s-all.nd b/ld/testsuite/ld-plugin/strip-1a-s-all.nd
index 612ba6a39b1..52265c2eb3d 100644
--- a/ld/testsuite/ld-plugin/strip-1a-s-all.nd
+++ b/ld/testsuite/ld-plugin/strip-1a-s-all.nd
@@ -1,3 +1,6 @@
 #...
-[0-9a-f]* C _?__gnu_lto_slim
+ + U foo2
+ + U foo3
+0+ T foo1
+0+ T main
 #pass
-- 
2.50.1