PowerPC addpcis fix

This came up because I was looking at ld/tmpdir/addpcis.o and noticed
the odd addends on REL16DX_HA.  They ought to both be -4.  The error
crept in due REL16DX_HA howto being pc-relative (as indeed it should
be), and code at gas/write.c:1001 after this comment
	      /* Make it pc-relative.  If the back-end code has not
		 selected a pc-relative reloc, cancel the adjustment
		 we do later on all pc-relative relocs.  */
*not* cancelling the pc-relative adjustment.  So I've made a dummy
non-relative split reloc so that the generic code handles this, rather
than attempting to add hacks later in md_apply_fix which would not be
very robust.  Having the new internal reloc also makes it easy to
support

 addpcis rx,sym@ha

as an equivalent to

 addpcis rx,(sym-0f)@ha
0:

The patch also fixes overflow checking, which must test whether the
addi will overflow too since @l relocs don't have any overflow check.

Lastly, since I was poking at md_apply_fix, I arranged to have the
generic gas/write.c code emit errors for subtraction expressions where
we lack reloc support.

include/
	* elf/ppc64.h (R_PPC64_16DX_HA): New.  Expand fake reloc comment.
	* elf/ppc.h (R_PPC_16DX_HA): Likewise.
bfd/
	* reloc.c (BFD_RELOC_PPC_16DX_HA): New.
	* elf64-ppc.c (ppc64_elf_howto_raw <R_PPC64_16DX_HA>): New howto.
	(ppc64_elf_reloc_type_lookup): Translate new bfd reloc.
	(ppc64_elf_ha_reloc): Correct overflow test on REL16DX_HA.
	(ppc64_elf_relocate_section): Likewise.
	* elf32-ppc.c (ppc_elf_howto_raw <R_PPC_16DX_HA>): New howto.
	(ppc_elf_reloc_type_lookup): Translate new bfd reloc.
	(ppc_elf_check_relocs): Handle R_PPC_16DX_HA to pacify gcc.
	* libbfd.h: Regenerate.
	* bfd-in2.h: Regenerate.
gas/
	* config/tc-ppc.c (md_assemble): Use BFD_RELOC_PPC_16DX_HA for addpcis.
	(md_apply_fix): Remove fx_subsy check.  Move code converting to
	pcrel reloc earlier and handle BFD_RELOC_PPC_16DX_HA.  Remove code
	emiiting errors on seeing fx_pcrel set on unexpected relocs, as
	that is done now by the generic code via..
	* config/tc-ppc.h (TC_FORCE_RELOCATION_SUB_LOCAL): ..this. Define.
	(TC_VALIDATE_FIX_SUB): Define.
ld/
	* testsuite/ld-powerpc/addpcis.d: Define ext1 and ext2 at
	limits of addpcis range.

1 files changed, 26 insertions, 7 deletions

diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c
index 7b8bacf..661ef26 100644
--- a/bfd/elf64-ppc.c
+++ b/bfd/elf64-ppc.c
@@ -2045,6 +2045,21 @@ static reloc_howto_type ppc64_elf_howto_raw[] = {
 	 0x1fffc1,		/* dst_mask */
 	 TRUE),			/* pcrel_offset */
 
+  /* A split-field reloc for addpcis, non-relative (gas internal use only).  */
+  HOWTO (R_PPC64_16DX_HA,	/* type */
+	 16,			/* rightshift */
+	 2,			/* size (0 = byte, 1 = short, 2 = long) */
+	 16,			/* bitsize */
+	 FALSE,			/* pc_relative */
+	 0,			/* bitpos */
+	 complain_overflow_signed, /* complain_on_overflow */
+	 ppc64_elf_ha_reloc,	/* special_function */
+	 "R_PPC64_16DX_HA",	/* name */
+	 FALSE,			/* partial_inplace */
+	 0,			/* src_mask */
+	 0x1fffc1,		/* dst_mask */
+	 FALSE),		/* pcrel_offset */
+
   /* Like R_PPC64_ADDR16_HI, but no overflow.  */
   HOWTO (R_PPC64_ADDR16_HIGH,	/* type */
 	 16,			/* rightshift */
@@ -2450,6 +2465,8 @@ ppc64_elf_reloc_type_lookup (bfd *abfd ATTRIBUTE_UNUSED,
       break;
     case BFD_RELOC_HI16_S_PCREL:		r = R_PPC64_REL16_HA;
       break;
+    case BFD_RELOC_PPC_16DX_HA:			r = R_PPC64_16DX_HA;
+      break;
     case BFD_RELOC_PPC_REL16DX_HA:		r = R_PPC64_REL16DX_HA;
       break;
     case BFD_RELOC_PPC64_ENTRY:			r = R_PPC64_ENTRY;
@@ -2512,7 +2529,7 @@ ppc64_elf_ha_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol,
   enum elf_ppc64_reloc_type r_type;
   long insn;
   bfd_size_type octets;
-  bfd_vma value;
+  bfd_vma value, field;
 
   /* If this is a relocatable link (output_bfd test tells us), just
      call the generic function.  Any adjustment will be done at final
@@ -2538,14 +2555,14 @@ ppc64_elf_ha_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol,
   value -= (reloc_entry->address
 	    + input_section->output_offset
 	    + input_section->output_section->vma);
-  value = (bfd_signed_vma) value >> 16;
+  field = (bfd_signed_vma) value >> 16;
 
   octets = reloc_entry->address * bfd_octets_per_byte (abfd);
   insn = bfd_get_32 (abfd, (bfd_byte *) data + octets);
   insn &= ~0x1fffc1;
-  insn |= (value & 0xffc1) | ((value & 0x3e) << 15);
+  insn |= (field & 0xffc1) | ((field & 0x3e) << 15);
   bfd_put_32 (abfd, insn, (bfd_byte *) data + octets);
-  if (value + 0x8000 > 0xffff)
+  if (value + 0x80000000 > 0xffffffff)
     return bfd_reloc_overflow;
   return bfd_reloc_ok;
 }
@@ -15238,17 +15255,19 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	    r = bfd_reloc_outofrange;
 	  else
 	    {
+	      bfd_signed_vma field;
+
 	      relocation += addend;
 	      relocation -= (rel->r_offset
 			     + input_section->output_offset
 			     + input_section->output_section->vma);
-	      relocation = (bfd_signed_vma) relocation >> 16;
+	      field = (bfd_signed_vma) relocation >> 16;
 	      insn = bfd_get_32 (input_bfd, contents + rel->r_offset);
 	      insn &= ~0x1fffc1;
-	      insn |= (relocation & 0xffc1) | ((relocation & 0x3e) << 15);
+	      insn |= (field & 0xffc1) | ((field & 0x3e) << 15);
 	      bfd_put_32 (input_bfd, insn, contents + rel->r_offset);
 	      r = bfd_reloc_ok;
-	      if (relocation + 0x8000 > 0xffff)
+	      if (relocation + 0x80000000 > 0xffffffff)
 		r = bfd_reloc_overflow;
 	    }
 	}