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.

3 files changed, 71 insertions, 81 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index ec6dbf7..30d07a8 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,13 @@
+2017-02-28  Alan Modra  <amodra@gmail.com>
+
+	* 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.
+
 2017-02-28  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* testsuite/gas/mips/jalr4.s: Add `jalr $0, $25' instructions.
diff --git a/gas/config/tc-ppc.c b/gas/config/tc-ppc.c
index d52850c..05e2c73 100644
--- a/gas/config/tc-ppc.c
+++ b/gas/config/tc-ppc.c
@@ -3151,7 +3151,7 @@ md_assemble (char *str)
 	      /* addpcis.  */
 	      if (opcode->opcode == (19 << 26) + (2 << 1)
 		  && reloc == BFD_RELOC_HI16_S)
-		reloc = BFD_RELOC_PPC_REL16DX_HA;
+		reloc = BFD_RELOC_PPC_16DX_HA;
 
 	      /* If VLE-mode convert LO/HI/HA relocations.  */
       	      if (opcode->flags & PPC_OPCODE_VLE)
@@ -6566,10 +6566,50 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg)
     }
 #endif
 
-  if (fixP->fx_subsy != (symbolS *) NULL)
+  /* We are only able to convert some relocs to pc-relative.  */
+  if (fixP->fx_pcrel)
+    {
+      switch (fixP->fx_r_type)
+	{
+	case BFD_RELOC_LO16:
+	  fixP->fx_r_type = BFD_RELOC_LO16_PCREL;
+	  break;
+
+	case BFD_RELOC_HI16:
+	  fixP->fx_r_type = BFD_RELOC_HI16_PCREL;
+	  break;
+
+	case BFD_RELOC_HI16_S:
+	  fixP->fx_r_type = BFD_RELOC_HI16_S_PCREL;
+	  break;
+
+	case BFD_RELOC_64:
+	  fixP->fx_r_type = BFD_RELOC_64_PCREL;
+	  break;
+
+	case BFD_RELOC_32:
+	  fixP->fx_r_type = BFD_RELOC_32_PCREL;
+	  break;
+
+	case BFD_RELOC_16:
+	  fixP->fx_r_type = BFD_RELOC_16_PCREL;
+	  break;
+
+	case BFD_RELOC_PPC_16DX_HA:
+	  fixP->fx_r_type = BFD_RELOC_PPC_REL16DX_HA;
+	  break;
+
+	default:
+	  break;
+	}
+    }
+  else if (!fixP->fx_done
+	   && fixP->fx_r_type == BFD_RELOC_PPC_16DX_HA)
     {
-      /* We can't actually support subtracting a symbol.  */
-      as_bad_where (fixP->fx_file, fixP->fx_line, _("expression too complex"));
+      /* addpcis is relative to next insn address.  */
+      value -= 4;
+      fixP->fx_r_type = BFD_RELOC_PPC_REL16DX_HA;
+      fixP->fx_pcrel = 1;
     }
 
   operand = NULL;
@@ -6651,6 +6691,7 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg)
 
     case BFD_RELOC_HI16_S:
     case BFD_RELOC_HI16_S_PCREL:
+    case BFD_RELOC_PPC_16DX_HA:
     case BFD_RELOC_PPC_REL16DX_HA:
 #ifdef OBJ_ELF
       if (REPORT_OVERFLOW_HI && ppc_obj64)
@@ -7078,83 +7119,6 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg)
 		       _("data in executable section"));
     }
 
-  /* We are only able to convert some relocs to pc-relative.  */
-  if (!fixP->fx_done && fixP->fx_pcrel)
-    {
-      switch (fixP->fx_r_type)
-	{
-	case BFD_RELOC_LO16:
-	  fixP->fx_r_type = BFD_RELOC_LO16_PCREL;
-	  break;
-
-	case BFD_RELOC_HI16:
-	  fixP->fx_r_type = BFD_RELOC_HI16_PCREL;
-	  break;
-
-	case BFD_RELOC_HI16_S:
-	  fixP->fx_r_type = BFD_RELOC_HI16_S_PCREL;
-	  break;
-
-	case BFD_RELOC_64:
-	  fixP->fx_r_type = BFD_RELOC_64_PCREL;
-	  break;
-
-	case BFD_RELOC_32:
-	  fixP->fx_r_type = BFD_RELOC_32_PCREL;
-	  break;
-
-	case BFD_RELOC_16:
-	  fixP->fx_r_type = BFD_RELOC_16_PCREL;
-	  break;
-
-	  /* Some of course are already pc-relative.  */
-	case BFD_RELOC_LO16_PCREL:
-	case BFD_RELOC_HI16_PCREL:
-	case BFD_RELOC_HI16_S_PCREL:
-	case BFD_RELOC_PPC_REL16DX_HA:
-	case BFD_RELOC_64_PCREL:
-	case BFD_RELOC_32_PCREL:
-	case BFD_RELOC_16_PCREL:
-	case BFD_RELOC_PPC_B16:
-	case BFD_RELOC_PPC_B16_BRTAKEN:
-	case BFD_RELOC_PPC_B16_BRNTAKEN:
-	case BFD_RELOC_PPC_B26:
-	case BFD_RELOC_PPC_LOCAL24PC:
-	case BFD_RELOC_24_PLT_PCREL:
-	case BFD_RELOC_32_PLT_PCREL:
-	case BFD_RELOC_64_PLT_PCREL:
-	case BFD_RELOC_PPC_VLE_REL8:
-	case BFD_RELOC_PPC_VLE_REL15:
-	case BFD_RELOC_PPC_VLE_REL24:
-	  break;
-
-	default:
-	  if (fixP->fx_addsy)
-	    {
-	      const char *sfile;
-	      unsigned int sline;
-
-	      /* Use expr_symbol_where to see if this is an
-		 expression symbol.  */
-	      if (expr_symbol_where (fixP->fx_addsy, &sfile, &sline))
-		as_bad_where (fixP->fx_file, fixP->fx_line,
-			      _("unresolved expression that must"
-				" be resolved"));
-	      else
-		as_bad_where (fixP->fx_file, fixP->fx_line,
-			      _("cannot emit PC relative %s relocation"
-				" against %s"),
-			      bfd_get_reloc_code_name (fixP->fx_r_type),
-			      S_GET_NAME (fixP->fx_addsy));
-	    }
-	  else
-	    as_bad_where (fixP->fx_file, fixP->fx_line,
-			  _("unable to resolve expression"));
-	  fixP->fx_done = 1;
-	  break;
-	}
-    }
-
 #ifdef OBJ_ELF
   ppc_elf_validate_fix (fixP, seg);
   fixP->fx_addnumber = value;
diff --git a/gas/config/tc-ppc.h b/gas/config/tc-ppc.h
index 077224b..514c223 100644
--- a/gas/config/tc-ppc.h
+++ b/gas/config/tc-ppc.h
@@ -257,6 +257,22 @@ extern void ppc_elf_end (void);
 extern int ppc_force_relocation (struct fix *);
 #endif
 
+#ifdef OBJ_ELF
+/* Don't allow the generic code to convert fixups involving the
+   subtraction of a label in the current section to pc-relative if we
+   don't have the necessary pc-relative relocation.  */
+#define TC_FORCE_RELOCATION_SUB_LOCAL(FIX, SEG)		\
+  (!((FIX)->fx_r_type == BFD_RELOC_LO16			\
+     || (FIX)->fx_r_type == BFD_RELOC_HI16		\
+     || (FIX)->fx_r_type == BFD_RELOC_HI16_S		\
+     || (FIX)->fx_r_type == BFD_RELOC_64		\
+     || (FIX)->fx_r_type == BFD_RELOC_32		\
+     || (FIX)->fx_r_type == BFD_RELOC_16		\
+     || (FIX)->fx_r_type == BFD_RELOC_PPC_16DX_HA))
+#endif
+
+#define TC_VALIDATE_FIX_SUB(FIX, SEG) 0
+
 /* call md_pcrel_from_section, not md_pcrel_from */
 #define MD_PCREL_FROM_SECTION(FIX, SEC) md_pcrel_from_section(FIX, SEC)
 extern long md_pcrel_from_section (struct fix *, segT);