PowerPC64 --no-pcrel-optimize

This new option effectively ignores R_PPC64_PCREL_OPT, disabling the
optimization of instructions marked by that relocation.  The patch
also disables GOT indirect to GOT/TOC pointer relative code editing
when --no-toc-optimize.

bfd/
	* elf64-ppc.h (struct ppc64_elf_params): Add no_pcrel_opt.
	* elf64-ppc.c (ppc64_elf_relocate_section): Disable GOT reloc
	optimizations when --no-toc-optimize.  Disable R_PPC64_PCREL_OPT
	optimization when --no-pcrel-optimize.
ld/
	* emultempl/ppc64elf.em (params): Init new field.
	(enum ppc64_opt): Add OPTION_NO_PCREL_OPT.
	(PARSE_AND_LIST_LONGOPTS, PARSE_AND_LIST_OPTIONS),
	(PARSE_AND_LIST_ARGS_CASES): Support --no-pcrel-optimize.

bfd/ChangeLog

@@ -1,3 +1,10 @@
+2020-08-13  Alan Modra  <amodra@gmail.com>
+
+	* elf64-ppc.h (struct ppc64_elf_params): Add no_pcrel_opt.
+	* elf64-ppc.c (ppc64_elf_relocate_section): Disable GOT reloc
+	optimizations when --no-toc-optimize.  Disable R_PPC64_PCREL_OPT
+	optimization when --no-pcrel-optimize.
+
 2020-08-13  Alan Modra  <amodra@gmail.com>
 
 	PR 26348

bfd/elf64-ppc.c

@@ -15903,7 +15903,8 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	  break;
 
 	case R_PPC64_GOT16_DS:
-	  if ((h ? h->elf.type : ELF_ST_TYPE (sym->st_info)) == STT_GNU_IFUNC)
+	  if ((h ? h->elf.type : ELF_ST_TYPE (sym->st_info)) == STT_GNU_IFUNC
+	      || !htab->do_toc_opt)
 	    break;
 	  from = TOCstart + htab->sec_info[input_section->id].toc_off;
 	  if (relocation + addend - from + 0x8000 < 0x10000
@@ -15922,7 +15923,8 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 
 	case R_PPC64_GOT16_LO_DS:
 	case R_PPC64_GOT16_HA:
-	  if ((h ? h->elf.type : ELF_ST_TYPE (sym->st_info)) == STT_GNU_IFUNC)
+	  if ((h ? h->elf.type : ELF_ST_TYPE (sym->st_info)) == STT_GNU_IFUNC
+	      || !htab->do_toc_opt)
 	    break;
 	  from = TOCstart + htab->sec_info[input_section->id].toc_off;
 	  if (relocation + addend - from + 0x80008000ULL < 0x100000000ULL
@@ -15945,34 +15947,38 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	  break;
 
 	case R_PPC64_GOT_PCREL34:
-	  if ((h ? h->elf.type : ELF_ST_TYPE (sym->st_info)) == STT_GNU_IFUNC)
+	  if ((h ? h->elf.type : ELF_ST_TYPE (sym->st_info)) == STT_GNU_IFUNC
+	      || !htab->do_toc_opt)
 	    break;
 	  from = (rel->r_offset
 		  + input_section->output_section->vma
 		  + input_section->output_offset);
-	  if (relocation - from + (1ULL << 33) < 1ULL << 34
+	  if (!(relocation - from + (1ULL << 33) < 1ULL << 34
-	      && SYMBOL_REFERENCES_LOCAL (info, &h->elf))
+		&& SYMBOL_REFERENCES_LOCAL (info, &h->elf)))
-	    {
+	    break;
+
 	  offset = rel->r_offset;
 	  pinsn = bfd_get_32 (input_bfd, contents + offset);
 	  pinsn <<= 32;
 	  pinsn |= bfd_get_32 (input_bfd, contents + offset + 4);
 	  if ((pinsn & ((-1ULL << 50) | (63ULL << 26)))
-		   == ((1ULL << 58) | (1ULL << 52) | (57ULL << 26) /* pld */))
+	      != ((1ULL << 58) | (1ULL << 52) | (57ULL << 26) /* pld */))
-		{
+	    break;
+
 	  /* Replace with paddi.  */
 	  pinsn += (2ULL << 56) + (14ULL << 26) - (57ULL << 26);
 	  r_type = R_PPC64_PCREL34;
 	  rel->r_info = ELF64_R_INFO (r_symndx, r_type);
 	  bfd_put_32 (input_bfd, pinsn >> 32, contents + offset);
 	  bfd_put_32 (input_bfd, pinsn, contents + offset + 4);
-		  goto pcrelopt;
+	  /* Fall through.  */
-		}
-	    }
-	  break;
 
 	case R_PPC64_PCREL34:
-	  if (SYMBOL_REFERENCES_LOCAL (info, &h->elf))
+	  if (!htab->params->no_pcrel_opt
+	      && rel + 1 < relend
+	      && rel[1].r_offset == rel->r_offset
+	      && rel[1].r_info == ELF64_R_INFO (0, R_PPC64_PCREL_OPT)
+	      && SYMBOL_REFERENCES_LOCAL (info, &h->elf))
 	    {
 	      offset = rel->r_offset;
 	      pinsn = bfd_get_32 (input_bfd, contents + offset);
@@ -15981,11 +15987,6 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 	      if ((pinsn & ((-1ULL << 50) | (63ULL << 26)))
 		   == ((1ULL << 58) | (2ULL << 56) | (1ULL << 52)
 		       | (14ULL << 26) /* paddi */))
-		{
-		pcrelopt:
-		  if (rel + 1 < relend
-		      && rel[1].r_offset == offset
-		      && rel[1].r_info == ELF64_R_INFO (0, R_PPC64_PCREL_OPT))
 		{
 		  bfd_vma off2 = rel[1].r_addend;
 		  if (off2 == 0)
@@ -16022,7 +16023,6 @@ ppc64_elf_relocate_section (bfd *output_bfd,
 		    }
 		}
 	    }
-	    }
 	  break;
 	}
 

bfd/elf64-ppc.h

@@ -57,6 +57,9 @@ struct ppc64_elf_params
   /* Whether to use power10 instructions in linkage stubs.  */
   int power10_stubs;
 
+  /* Whether R_PPC64_PCREL_OPT should be ignored.  */
+  int no_pcrel_opt;
+
   /* Whether to canonicalize .opd so that there are no overlapping
      .opd entries.  */
   int non_overlapping_opd;

ld/ChangeLog

@@ -1,3 +1,10 @@
+2020-08-13  Alan Modra  <amodra@gmail.com>
+
+	* emultempl/ppc64elf.em (params): Init new field.
+	(enum ppc64_opt): Add OPTION_NO_PCREL_OPT.
+	(PARSE_AND_LIST_LONGOPTS, PARSE_AND_LIST_OPTIONS),
+	(PARSE_AND_LIST_ARGS_CASES): Support --no-pcrel-optimize.
+
 2020-08-10  Nick Clifton  <nickc@redhat.com>
 
 	PR ld/21351

ld/emultempl/ppc64elf.em

@@ -38,7 +38,7 @@ static struct ppc64_elf_params params = { NULL,
 					  &ppc_layout_sections_again,
 					  1, -1, -1, 0,
 					  ${DEFAULT_PLT_STATIC_CHAIN-0}, -1, 5,
-					  -1, -1, 0, -1, -1, 0};
+					  -1, -1, 0, 0, -1, -1, 0};
 
 /* Fake input file for stubs.  */
 static lang_input_statement_type *stub_file;
@@ -686,6 +686,7 @@ enum ppc64_opt
   OPTION_NO_PLT_LOCALENTRY,
   OPTION_POWER10_STUBS,
   OPTION_NO_POWER10_STUBS,
+  OPTION_NO_PCREL_OPT,
   OPTION_STUBSYMS,
   OPTION_NO_STUBSYMS,
   OPTION_SAVRES,
@@ -717,6 +718,7 @@ PARSE_AND_LIST_LONGOPTS=${PARSE_AND_LIST_LONGOPTS}'
   { "plt-localentry", optional_argument, NULL, OPTION_PLT_LOCALENTRY },
   { "no-plt-localentry", no_argument, NULL, OPTION_NO_PLT_LOCALENTRY },
   { "power10-stubs", optional_argument, NULL, OPTION_POWER10_STUBS },
+  { "no-pcrel-optimize", no_argument, NULL, OPTION_NO_PCREL_OPT },
   { "no-power10-stubs", no_argument, NULL, OPTION_NO_POWER10_STUBS },
   { "emit-stub-syms", no_argument, NULL, OPTION_STUBSYMS },
   { "no-emit-stub-syms", no_argument, NULL, OPTION_NO_STUBSYMS },
@@ -776,6 +778,9 @@ PARSE_AND_LIST_OPTIONS=${PARSE_AND_LIST_OPTIONS}'
   --power10-stubs [=auto]     Use Power10 PLT call stubs (default auto)\n"
 		   ));
   fprintf (file, _("\
+  --no-pcrel-optimize         Don'\''t perform R_PPC64_PCREL_OPT optimization\n"
+		   ));
+  fprintf (file, _("\
   --no-power10-stubs          Don'\''t use Power10 PLT call stubs\n"
 		   ));
   fprintf (file, _("\
@@ -909,6 +914,10 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
       params.power10_stubs = 0;
       break;
 
+    case OPTION_NO_PCREL_OPT:
+      params.no_pcrel_opt = 1;
+      break;
+
     case OPTION_STUBSYMS:
       params.emit_stub_syms = 1;
       break;
@@ -985,6 +994,7 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
       params.no_multi_toc = 1;
       no_toc_sort = 1;
       params.plt_static_chain = 1;
+      params.no_pcrel_opt = 1;
       return FALSE;
 '