RISC-V: Remove R_RISCV_GNU_VTINHERIT/R_RISCV_GNU_VTENTRY

They were legacy relocation types copied from other ports.  The related
-fvtable-gc was removed from GCC in 2003.

The associated assembler directives (.vtable_inherit and .vtable_entry)
have never been supported by the RISC-V port.  Remove related ld code.

Link: riscv-non-isa/riscv-elf-psabi-doc#323

Author: MaskRay

bfd/elfnn-riscv.c

@@ -932,16 +932,6 @@ riscv_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 
 	  break;
 
-	case R_RISCV_GNU_VTINHERIT:
-	  if (!bfd_elf_gc_record_vtinherit (abfd, sec, h, rel->r_offset))
-	    return false;
-	  break;
-
-	case R_RISCV_GNU_VTENTRY:
-	  if (!bfd_elf_gc_record_vtentry (abfd, sec, h, rel->r_addend))
-	    return false;
-	  break;
-
 	default:
 	  break;
 	}
@@ -950,24 +940,6 @@ riscv_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
   return true;
 }
 
-static asection *
-riscv_elf_gc_mark_hook (asection *sec,
-			struct bfd_link_info *info,
-			Elf_Internal_Rela *rel,
-			struct elf_link_hash_entry *h,
-			Elf_Internal_Sym *sym)
-{
-  if (h != NULL)
-    switch (ELFNN_R_TYPE (rel->r_info))
-      {
-      case R_RISCV_GNU_VTINHERIT:
-      case R_RISCV_GNU_VTENTRY:
-	return NULL;
-      }
-
-  return _bfd_elf_gc_mark_hook (sec, info, rel, h, sym);
-}
-
 /* Adjust a symbol defined by a dynamic object and referenced by a
    regular object.  The current definition is in some section of the
    dynamic object, but we're not including those sections.  We have to
@@ -2027,8 +1999,7 @@ riscv_elf_relocate_section (bfd *output_bfd,
       char *msg_buf = NULL;
       bool resolved_to_zero;
 
-      if (howto == NULL
-	  || r_type == R_RISCV_GNU_VTINHERIT || r_type == R_RISCV_GNU_VTENTRY)
+      if (howto == NULL)
 	continue;
 
       /* This is a final link.  */
@@ -5260,7 +5231,6 @@ riscv_elf_merge_symbol_attribute (struct elf_link_hash_entry *h,
 #define elf_backend_relocate_section		riscv_elf_relocate_section
 #define elf_backend_finish_dynamic_symbol	riscv_elf_finish_dynamic_symbol
 #define elf_backend_finish_dynamic_sections	riscv_elf_finish_dynamic_sections
-#define elf_backend_gc_mark_hook		riscv_elf_gc_mark_hook
 #define elf_backend_plt_sym_val			riscv_elf_plt_sym_val
 #define elf_backend_grok_prstatus		riscv_elf_grok_prstatus
 #define elf_backend_grok_psinfo			riscv_elf_grok_psinfo

bfd/elfxx-riscv.c

@@ -599,35 +599,9 @@ static reloc_howto_type howto_table[] =
 	 MINUS_ONE,			/* dst_mask */
 	 false),			/* pcrel_offset */
 
-  /* GNU extension to record C++ vtable hierarchy */
-  HOWTO (R_RISCV_GNU_VTINHERIT,		/* type */
-	 0,				/* rightshift */
-	 8,				/* size */
-	 0,				/* bitsize */
-	 false,				/* pc_relative */
-	 0,				/* bitpos */
-	 complain_overflow_dont,	/* complain_on_overflow */
-	 NULL,				/* special_function */
-	 "R_RISCV_GNU_VTINHERIT",	/* name */
-	 false,				/* partial_inplace */
-	 0,				/* src_mask */
-	 0,				/* dst_mask */
-	 false),			/* pcrel_offset */
-
-  /* GNU extension to record C++ vtable member usage */
-  HOWTO (R_RISCV_GNU_VTENTRY,		/* type */
-	 0,				/* rightshift */
-	 8,				/* size */
-	 0,				/* bitsize */
-	 false,				/* pc_relative */
-	 0,				/* bitpos */
-	 complain_overflow_dont,	/* complain_on_overflow */
-	 _bfd_elf_rel_vtable_reloc_fn,	/* special_function */
-	 "R_RISCV_GNU_VTENTRY",		/* name */
-	 false,				/* partial_inplace */
-	 0,				/* src_mask */
-	 0,				/* dst_mask */
-	 false),			/* pcrel_offset */
+  /* 41 and 42 are reserved.  */
+  EMPTY_HOWTO (0),
+  EMPTY_HOWTO (0),
 
   /* Indicates an alignment statement.  The addend field encodes how many
      bytes of NOPs follow the statement.  The desired alignment is the

include/elf/riscv.h

@@ -71,8 +71,6 @@ START_RELOC_NUMBERS (elf_riscv_reloc_type)
   RELOC_NUMBER (R_RISCV_SUB16, 38)
   RELOC_NUMBER (R_RISCV_SUB32, 39)
   RELOC_NUMBER (R_RISCV_SUB64, 40)
-  RELOC_NUMBER (R_RISCV_GNU_VTINHERIT, 41)
-  RELOC_NUMBER (R_RISCV_GNU_VTENTRY, 42)
   RELOC_NUMBER (R_RISCV_ALIGN, 43)
   RELOC_NUMBER (R_RISCV_RVC_BRANCH, 44)
   RELOC_NUMBER (R_RISCV_RVC_JUMP, 45)