x86-64: Generate branch with PLT32 relocation

[external/binutils.git] / gas / config / tc-i386.c

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 552c1b8..1a5be1b 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -7023,12 +7023,46 @@ output_branch (void)
   frag_var (rs_machine_dependent, 5, i.reloc[0], subtype, sym, off, p);
 }
 
+#if defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)
+/* Return TRUE iff PLT32 relocation should be used for branching to
+   symbol S.  */
+
+static bfd_boolean
+need_plt32_p (symbolS *s)
+{
+  /* PLT32 relocation is ELF only.  */
+  if (!IS_ELF)
+    return FALSE;
+
+  /* Since there is no need to prepare for PLT branch on x86-64, we
+     can generate R_X86_64_PLT32, instead of R_X86_64_PC32, which can
+     be used as a marker for 32-bit PC-relative branches.  */
+  if (!object_64bit)
+    return FALSE;
+
+  /* Weak or undefined symbol need PLT32 relocation.  */
+  if (S_IS_WEAK (s) || !S_IS_DEFINED (s))
+    return TRUE;
+
+  /* Non-global symbol doesn't need PLT32 relocation.  */
+  if (! S_IS_EXTERNAL (s))
+    return FALSE;
+
+  /* Other global symbols need PLT32 relocation.  NB: Symbol with
+     non-default visibilities are treated as normal global symbol
+     so that PLT32 relocation can be used as a marker for 32-bit
+     PC-relative branches.  It is useful for linker relaxation.  */
+  return TRUE;
+}
+#endif
+
 static void
 output_jump (void)
 {
   char *p;
   int size;
   fixS *fixP;
+  bfd_reloc_code_real_type jump_reloc = i.reloc[0];
 
   if (i.tm.opcode_modifier.jumpbyte)
     {
@@ -7096,8 +7130,17 @@ output_jump (void)
       abort ();
     }
 
+#if defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)
+  if (size == 4
+      && jump_reloc == NO_RELOC
+      && need_plt32_p (i.op[0].disps->X_add_symbol))
+    jump_reloc = BFD_RELOC_X86_64_PLT32;
+#endif
+
+  jump_reloc = reloc (size, 1, 1, jump_reloc);
+
   fixP = fix_new_exp (frag_now, p - frag_now->fr_literal, size,
-                     i.op[0].disps, 1, reloc (size, 1, 1, i.reloc[0]));
+                     i.op[0].disps, 1, jump_reloc);
 
   /* All jumps handled here are signed, but don't use a signed limit
      check for 32 and 16 bit jumps as we want to allow wrap around at
@@ -9315,6 +9358,10 @@ md_estimate_size_before_relax (fragS *fragP, segT segment)
        reloc_type = (enum bfd_reloc_code_real) fragP->fr_var;
       else if (size == 2)
        reloc_type = BFD_RELOC_16_PCREL;
+#if defined (OBJ_ELF) || defined (OBJ_MAYBE_ELF)
+      else if (need_plt32_p (fragP->fr_symbol))
+       reloc_type = BFD_RELOC_X86_64_PLT32;
+#endif
       else
        reloc_type = BFD_RELOC_32_PCREL;