[PATCH] LTO: Handle __real_SYM reference in IR

[H.J. Lu]

When an IR symbol SYM is referenced in IR via __real_SYM, its resolution
should be LDPR_PREVAILING_DEF, not PREVAILING_DEF_IRONLY, since LTO
doesn't know that __real_SYM should be resolved by SYM.

bfd/

	PR ld/29086
	* elflink.c (_bfd_elf_merge_symbol): Mark SYM is referenced in
	IR if __real_SYM is referenced in IR.

include/

	PR ld/29086
	* bfdlink.h (bfd_link_hash_entry): Add ir_ref_real.

ld/

	PR ld/29086
	* plugin.c (get_symbols): Resolve SYM definition to
	LDPR_PREVAILING_DEF for __real_SYM reference in IR.
	* testsuite/ld-plugin/lto.exp: Run PR ld/29086 test.
	* testsuite/ld-plugin/pr29086.c: New file.
---
 bfd/elflink.c                    | 15 +++++++++++++--
 include/bfdlink.h                |  4 ++++
 ld/plugin.c                      |  7 +++++--
 ld/testsuite/ld-plugin/lto.exp   |  8 ++++++++
 ld/testsuite/ld-plugin/pr29086.c | 19 +++++++++++++++++++
 5 files changed, 49 insertions(+), 4 deletions(-)
 create mode 100644 ld/testsuite/ld-plugin/pr29086.c

diff --git a/bfd/elflink.c b/bfd/elflink.c
index b54ee517c75..ced07e40524 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -1101,8 +1101,19 @@ _bfd_elf_merge_symbol (bfd *abfd,
   if (! bfd_is_und_section (sec))
     h = elf_link_hash_lookup (elf_hash_table (info), name, true, false, false);
   else
-    h = ((struct elf_link_hash_entry *)
-	 bfd_wrapped_link_hash_lookup (abfd, info, name, true, false, false));
+    {
+      h = ((struct elf_link_hash_entry *)
+	   bfd_wrapped_link_hash_lookup (abfd, info, name, true, false,
+					 false));
+      /* Mark SYM is referenced in IR if __real_SYM is referenced in
+	 IR.  */
+      if (h != NULL
+	  && info->wrap_hash != NULL
+	  && (abfd->flags & BFD_PLUGIN) != 0
+	  && strcmp (h->root.root.string,
+		     name + sizeof "__real_" - 1) == 0)
+	h->root.ir_ref_real = 1;
+    }
   if (h == NULL)
     return false;
   *sym_hash = h;
diff --git a/include/bfdlink.h b/include/bfdlink.h
index b16f3f44ca5..3b8cc7f8f96 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -114,6 +114,10 @@ struct bfd_link_hash_entry
      as distinct from a LTO IR object file.  */
   unsigned int non_ir_ref_dynamic : 1;
 
+  /* The symbol, SYM, is referenced by __real_SYM in an LTO IR object
+     file.  */
+  unsigned int ir_ref_real : 1;
+
   /* Symbol is a built-in define.  These will be overridden by PROVIDE
      in a linker script.  */
   unsigned int linker_def : 1;
diff --git a/ld/plugin.c b/ld/plugin.c
index 6db52d16802..c8cdf580a67 100644
--- a/ld/plugin.c
+++ b/ld/plugin.c
@@ -863,8 +863,11 @@ get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms,
 	  /* We need to know if the sym is referenced from non-IR files.  Or
 	     even potentially-referenced, perhaps in a future final link if
 	     this is a partial one, perhaps dynamically at load-time if the
-	     symbol is externally visible.  Also check for wrapper symbol.  */
-	  if (blhe->non_ir_ref_regular || wrap_status == wrapper)
+	     symbol is externally visible.  Also check for __real_SYM
+	     reference and wrapper symbol.  */
+	  if (blhe->non_ir_ref_regular
+	      || blhe->ir_ref_real
+	      || wrap_status == wrapper)
 	    res = LDPR_PREVAILING_DEF;
 	  else if (wrap_status == wrapped)
 	    res = LDPR_RESOLVED_IR;
diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp
index 33af6c45a41..fa5d2500aa3 100644
--- a/ld/testsuite/ld-plugin/lto.exp
+++ b/ld/testsuite/ld-plugin/lto.exp
@@ -522,6 +522,14 @@ set lto_link_elf_tests [list \
    {{"nm" {-D} "pr28849.d"}} \
    "pr28849" \
   ] \
+  [list \
+   "PR ld/pr29086" \
+   "-Wl,--wrap=foo" \
+   "-O0 -flto" \
+   {pr29086.c} \
+   {} \
+   "pr29086" \
+  ] \
 ]
 
 # PR 14918 checks that libgcc is not spuriously included in a shared link of
diff --git a/ld/testsuite/ld-plugin/pr29086.c b/ld/testsuite/ld-plugin/pr29086.c
new file mode 100644
index 00000000000..d333d68e262
--- /dev/null
+++ b/ld/testsuite/ld-plugin/pr29086.c
@@ -0,0 +1,19 @@
+int
+foo (void)
+{
+  return 0;
+}
+
+int
+main ()
+{
+  return foo ();
+}
+
+extern int __real_foo (void);
+
+int
+__wrap_foo (void)
+{
+  return __real_foo ();
+}
-- 
2.35.1