LTO: Handle __real_SYM reference in IR

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
	* linker.c (bfd_wrapped_link_hash_lookup): Mark SYM is referenced
	via __real_SYM.

include/

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

ld/

	PR ld/29086
	* plugin.c (get_symbols): Resolve SYM definition to
	LDPR_PREVAILING_DEF for __real_SYM reference.
	* testsuite/ld-plugin/lto.exp: Run PR ld/29086 test.
	* testsuite/ld-plugin/pr29086.c: New file.

bfd/linker.c

@@ -599,6 +599,7 @@ bfd_wrapped_link_hash_lookup (bfd *abfd,
 	  n[1] = '\0';
 	  strcat (n, l + sizeof REAL - 1);
 	  h = bfd_link_hash_lookup (info->hash, n, create, true, follow);
+	  h->ref_real = 1;
 	  free (n);
 	  return h;
 	}

include/bfdlink.h

@@ -114,6 +114,9 @@ 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 object file.  */
+  unsigned int ref_real : 1;
+
   /* Symbol is a built-in define.  These will be overridden by PROVIDE
      in a linker script.  */
   unsigned int linker_def : 1;

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->ref_real
+	      || wrap_status == wrapper)
 	    res = LDPR_PREVAILING_DEF;
 	  else if (wrap_status == wrapped)
 	    res = LDPR_RESOLVED_IR;

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

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 ();
+}