x86-64: Add R_X86_64_CODE_4_GOTPCRELX

For

	mov        name@GOTPCREL(%rip), %reg
	test       %reg, name@GOTPCREL(%rip)
	binop      name@GOTPCREL(%rip), %reg

where binop is one of adc, add, add, cmp, or, sbb, sub, xor instructions,
add

 # define R_X86_64_CODE_4_GOTPCRELX  43

if the instruction starts at 4 bytes before the relocation offset.  It
similar to R_X86_64_GOTPCRELX.  Linker can treat R_X86_64_CODE_4_GOTPCRELX
as R_X86_64_GOTPCREL or convert the above instructions to

	lea	name(%rip), %reg
	mov	$name, %reg
	test	$name, %reg
	binop	$name, %reg

if the instruction is encoded with the REX2 prefix when possible.

bfd/

	* elf64-x86-64.c (x86_64_elf_howto_table): Add
	R_X86_64_CODE_4_GOTPCRELX.
	(R_X86_64_standard): Updated.
	(x86_64_reloc_map): Add BFD_RELOC_X86_64_CODE_4_GOTPCRELX.
	(elf_x86_64_convert_load_reloc): Handle R_X86_64_CODE_4_GOTPCRELX.
	(elf_x86_64_scan_relocs): Likewise.
	(elf_x86_64_relocate_section): Likewise.
	* reloc.c (bfd_reloc_code_real): Add
	BFD_RELOC_X86_64_CODE_4_GOTPCRELX.
	* bfd-in2.h: Regenerated.
	* libbfd.h: Likewise.

gas/

	* write.h (fix): Add fx_tcbit3.  Change fx_unused to 1 bit.
	* config/tc-i386.c (tc_i386_fix_adjustable): Handle
	BFD_RELOC_X86_64_CODE_4_GOTPCRELX.
	(tc_gen_reloc): Likewise.
	(output_disp): Set fixP->fx_tcbit3 for REX2 prefix.
	(i386_validate_fix): Generate BFD_RELOC_X86_64_CODE_4_GOTPCRELX
	if fixp->fx_tcbit3 is set.
	* config/tc-i386.h (TC_FORCE_RELOCATION_LOCAL): Add
	BFD_RELOC_X86_64_CODE_4_GOTPCRELX.
	(TC_FORCE_RELOCATION_ABS): Likewise.
	* testsuite/gas/i386/x86-64-gotpcrel.s: Add tests for
	R_X86_64_CODE_4_GOTPCRELX.
	* testsuite/gas/i386/x86-64-localpic.s: Likewise.
	* testsuite/gas/i386/x86-64-gotpcrel.d: Updated.
	* testsuite/gas/i386/x86-64-localpic.d: Likewise.
	* testsuite/gas/i386/ilp32/x86-64-localpic.d: Likewise.

include/

	* elf/x86-64.h (elf_x86_64_reloc_type): Add
	R_X86_64_CODE_4_GOTPCRELX.

ld/

	* testsuite/ld-x86-64/apx-load1.s: New file.
	* testsuite/ld-x86-64/apx-load1a.d: Likewise.
	* testsuite/ld-x86-64/apx-load1b.d: Likewise.
	* testsuite/ld-x86-64/apx-load1c.d: Likewise.
	* testsuite/ld-x86-64/apx-load1d.d: Likewise.
	* testsuite/ld-x86-64/x86-64.exp: Run apx-load1a, apx-load1b,
	apx-load1c and apx-load1d.

4 files changed, 59 insertions, 18 deletions

diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 7828459..96709da 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -3891,6 +3891,7 @@ enum bfd_reloc_code_real
   BFD_RELOC_X86_64_PLT32_BND,
   BFD_RELOC_X86_64_GOTPCRELX,
   BFD_RELOC_X86_64_REX_GOTPCRELX,
+  BFD_RELOC_X86_64_CODE_4_GOTPCRELX,
 
   /* ns32k relocations.  */
   BFD_RELOC_NS32K_IMM_8,
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 3b7a8ae..a2d1b6f 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -170,12 +170,15 @@ static reloc_howto_type x86_64_elf_howto_table[] =
   HOWTO(R_X86_64_REX_GOTPCRELX, 0, 4, 32, true, 0, complain_overflow_signed,
 	bfd_elf_generic_reloc, "R_X86_64_REX_GOTPCRELX", false, 0, 0xffffffff,
 	true),
+  HOWTO(R_X86_64_CODE_4_GOTPCRELX, 0, 4, 32, true, 0, complain_overflow_signed,
+	bfd_elf_generic_reloc, "R_X86_64_CODE_4_GOTPCRELX", false, 0, 0xffffffff,
+	true),
 
   /* We have a gap in the reloc numbers here.
      R_X86_64_standard counts the number up to this point, and
      R_X86_64_vt_offset is the value to subtract from a reloc type of
      R_X86_64_GNU_VT* to form an index into this table.  */
-#define R_X86_64_standard (R_X86_64_REX_GOTPCRELX + 1)
+#define R_X86_64_standard (R_X86_64_CODE_4_GOTPCRELX + 1)
 #define R_X86_64_vt_offset (R_X86_64_GNU_VTINHERIT - R_X86_64_standard)
 
 /* GNU extension to record C++ vtable hierarchy.  */
@@ -244,6 +247,7 @@ static const struct elf_reloc_map x86_64_reloc_map[] =
   { BFD_RELOC_X86_64_PLT32_BND,	R_X86_64_PLT32_BND, },
   { BFD_RELOC_X86_64_GOTPCRELX, R_X86_64_GOTPCRELX, },
   { BFD_RELOC_X86_64_REX_GOTPCRELX, R_X86_64_REX_GOTPCRELX, },
+  { BFD_RELOC_X86_64_CODE_4_GOTPCRELX, R_X86_64_CODE_4_GOTPCRELX, },
   { BFD_RELOC_VTABLE_INHERIT,	R_X86_64_GNU_VTINHERIT, },
   { BFD_RELOC_VTABLE_ENTRY,	R_X86_64_GNU_VTENTRY, },
 };
@@ -1586,7 +1590,8 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
   bfd_vma roff = irel->r_offset;
   bfd_vma abs_relocation;
 
-  if (roff < (r_type == R_X86_64_REX_GOTPCRELX ? 3 : 2))
+  if (roff < (r_type == R_X86_64_CODE_4_GOTPCRELX
+	      ? 4 : (r_type == R_X86_64_REX_GOTPCRELX ? 3 : 2)))
     return true;
 
   raddend = irel->r_addend;
@@ -1597,8 +1602,18 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
   htab = elf_x86_hash_table (link_info, X86_64_ELF_DATA);
   is_pic = bfd_link_pic (link_info);
 
-  relocx = (r_type == R_X86_64_GOTPCRELX
-	    || r_type == R_X86_64_REX_GOTPCRELX);
+  if (r_type == R_X86_64_CODE_4_GOTPCRELX)
+    {
+      /* Skip if this isn't a REX2 instruction.  */
+      opcode = bfd_get_8 (abfd, contents + roff - 4);
+      if (opcode != 0xd5)
+	return true;
+
+      relocx = true;
+    }
+  else
+    relocx = (r_type == R_X86_64_GOTPCRELX
+	      || r_type == R_X86_64_REX_GOTPCRELX);
 
   /* TRUE if --no-relax is used.  */
   no_overflow = link_info->disable_target_specific_optimizations > 1;
@@ -1610,9 +1625,9 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
   /* Convert mov to lea since it has been done for a while.  */
   if (opcode != 0x8b)
     {
-      /* Only convert R_X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX
-	 for call, jmp or one of adc, add, and, cmp, or, sbb, sub,
-	 test, xor instructions.  */
+      /* Only convert R_X86_64_GOTPCRELX, R_X86_64_REX_GOTPCRELX
+	 and R_X86_64_CODE_4_GOTPCRELX for call, jmp or one of adc,
+	 add, and, cmp, or, sbb, sub, test, xor instructions.  */
       if (!relocx)
 	return true;
     }
@@ -1797,13 +1812,22 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
     }
   else
     {
-      unsigned int rex;
+      unsigned int rex = 0;
       unsigned int rex_mask = REX_R;
+      unsigned int rex2 = 0;
+      unsigned int rex2_mask = REX_R | REX_R << 4;
+      bool rex_w = false;
 
-      if (r_type == R_X86_64_REX_GOTPCRELX)
-	rex = bfd_get_8 (abfd, contents + roff - 3);
-      else
-	rex = 0;
+      if (r_type == R_X86_64_CODE_4_GOTPCRELX)
+	{
+	  rex2 = bfd_get_8 (abfd, contents + roff - 3);
+	  rex_w = (rex2 & REX_W) != 0;
+	}
+      else if (r_type == R_X86_64_REX_GOTPCRELX)
+	{
+	  rex = bfd_get_8 (abfd, contents + roff - 3);
+	  rex_w = (rex & REX_W) != 0;
+	}
 
       if (opcode == 0x8b)
 	{
@@ -1824,8 +1848,7 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 	      opcode = 0xc7;
 	      modrm = bfd_get_8 (abfd, contents + roff - 1);
 	      modrm = 0xc0 | (modrm & 0x38) >> 3;
-	      if ((rex & REX_W) != 0
-		  && ABI_64_P (link_info->output_bfd))
+	      if (rex_w && ABI_64_P (link_info->output_bfd))
 		{
 		  /* Keep the REX_W bit in REX byte for LP64.  */
 		  r_type = R_X86_64_32S;
@@ -1837,8 +1860,9 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 		     use R_X86_64_32 and clear the W bit to avoid
 		     sign-extend imm32 to imm64.  */
 		  r_type = R_X86_64_32;
-		  /* Clear the W bit in REX byte.  */
+		  /* Clear the W bit in REX byte and REX2 payload.  */
 		  rex_mask |= REX_W;
+		  rex2_mask |= REX_W;
 		  goto rewrite_modrm_rex;
 		}
 	    }
@@ -1867,7 +1891,7 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 
 	  /* Use R_X86_64_32 with 32-bit operand to avoid relocation
 	     overflow when sign-extending imm32 to imm64.  */
-	  r_type = (rex & REX_W) != 0 ? R_X86_64_32S : R_X86_64_32;
+	  r_type = rex_w ? R_X86_64_32S : R_X86_64_32;
 
 	rewrite_modrm_rex:
 	  if (abs_relocation)
@@ -1893,6 +1917,13 @@ elf_x86_64_convert_load_reloc (bfd *abfd,
 	      rex = (rex & ~rex_mask) | (rex & REX_R) >> 2;
 	      bfd_put_8 (abfd, rex, contents + roff - 3);
 	    }
+	  else if (rex2)
+	    {
+	      /* Move the R bits to the B bits in REX2 payload byte.  */
+	      rex2 = ((rex2 & ~rex2_mask)
+		      | (rex2 & (REX_R | REX_R << 4)) >> 2);
+	      bfd_put_8 (abfd, rex2, contents + roff - 3);
+	    }
 
 	  /* No addend for R_X86_64_32/R_X86_64_32S relocations.  */
 	  irel->r_addend = 0;
@@ -2058,7 +2089,8 @@ elf_x86_64_scan_relocs (bfd *abfd, struct bfd_link_info *info,
       converted_reloc = false;
       if ((r_type == R_X86_64_GOTPCREL
 	   || r_type == R_X86_64_GOTPCRELX
-	   || r_type == R_X86_64_REX_GOTPCRELX)
+	   || r_type == R_X86_64_REX_GOTPCRELX
+	   || r_type == R_X86_64_CODE_4_GOTPCRELX)
 	  && (h == NULL || h->type != STT_GNU_IFUNC))
 	{
 	  Elf_Internal_Rela *irel = (Elf_Internal_Rela *) rel;
@@ -2108,6 +2140,7 @@ elf_x86_64_scan_relocs (bfd *abfd, struct bfd_link_info *info,
 	case R_X86_64_GOTPCREL:
 	case R_X86_64_GOTPCRELX:
 	case R_X86_64_REX_GOTPCRELX:
+	case R_X86_64_CODE_4_GOTPCRELX:
 	case R_X86_64_TLSGD:
 	case R_X86_64_GOT64:
 	case R_X86_64_GOTPCREL64:
@@ -2710,6 +2743,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 	    case R_X86_64_GOTPCREL:
 	    case R_X86_64_GOTPCRELX:
 	    case R_X86_64_REX_GOTPCRELX:
+	    case R_X86_64_CODE_4_GOTPCRELX:
 	    case R_X86_64_GOTPCREL64:
 	      base_got = htab->elf.sgot;
 	      off = h->got.offset;
@@ -2935,6 +2969,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 	case R_X86_64_GOTPCREL:
 	case R_X86_64_GOTPCRELX:
 	case R_X86_64_REX_GOTPCRELX:
+	case R_X86_64_CODE_4_GOTPCRELX:
 	case R_X86_64_GOTPCREL64:
 	  /* Use global offset table entry as symbol value.  */
 	case R_X86_64_GOTPLT64:
@@ -3025,7 +3060,8 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 		      && !(sym->st_shndx == SHN_ABS
 			   && (r_type == R_X86_64_GOTPCREL
 			       || r_type == R_X86_64_GOTPCRELX
-			       || r_type == R_X86_64_REX_GOTPCRELX)))
+			       || r_type == R_X86_64_REX_GOTPCRELX
+			       || r_type == R_X86_64_CODE_4_GOTPCRELX)))
 		    relative_reloc = true;
 		}
 	    }
@@ -3063,6 +3099,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
 	  if (r_type != R_X86_64_GOTPCREL
 	      && r_type != R_X86_64_GOTPCRELX
 	      && r_type != R_X86_64_REX_GOTPCRELX
+	      && r_type != R_X86_64_CODE_4_GOTPCRELX
 	      && r_type != R_X86_64_GOTPCREL64)
 	    relocation -= htab->elf.sgotplt->output_section->vma
 			  - htab->elf.sgotplt->output_offset;
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index 8dab441..8873faf 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -1460,6 +1460,7 @@ static const char *const bfd_reloc_code_real_names[] = { "@@uninitialized@@",
   "BFD_RELOC_X86_64_PLT32_BND",
   "BFD_RELOC_X86_64_GOTPCRELX",
   "BFD_RELOC_X86_64_REX_GOTPCRELX",
+  "BFD_RELOC_X86_64_CODE_4_GOTPCRELX",
   "BFD_RELOC_NS32K_IMM_8",
   "BFD_RELOC_NS32K_IMM_16",
   "BFD_RELOC_NS32K_IMM_32",
diff --git a/bfd/reloc.c b/bfd/reloc.c
index 6fd0f1f..56d852d 100644
--- a/bfd/reloc.c
+++ b/bfd/reloc.c
@@ -2475,6 +2475,8 @@ ENUMX
   BFD_RELOC_X86_64_GOTPCRELX
 ENUMX
   BFD_RELOC_X86_64_REX_GOTPCRELX
+ENUMX
+  BFD_RELOC_X86_64_CODE_4_GOTPCRELX
 ENUMDOC
   x86-64/elf relocations.