Compact EH Support

The specification for the Compact EH format is available at:
https://github.com/MentorEmbedded/cxx-abi/blob/master/MIPSCompactEH.pdf

2015-05-28  Catherine Moore  <clm@codesourcery.com>
	    Bernd Schmidt <bernds@codesourcery.com>
	    Paul Brook <paul@codesourcery.com>

	bfd/
	* bfd-in2.h: Regenerated.
	* elf-bfd.h (DWARF2_EH_HDR, COMPACT_EH_HDR): Define.
	(COMPACT_EH_CANT_UNWIND_OPCODE): Define.
	(dwarf_eh_frame_hdr_info): Move dwarf-specific fields from
	eh_frame_hdr_info.
	(compact_eh_frame_hdr_info): Declare.
	(eh_frame_hdr_info):  Redeclare with union for dwarf-specific
	fields and compact-eh fields.
	(elf_backend_data): Add cant_unwind_opcode and compact_eh_encoding.
	(bfd_elf_section_data): Add eh_frame_entry_field.
	(elf_section_eh_frame_entry): Define.
	(bfd_elf_parse_eh_frame_entries): Declare.
	(_bfd_elf_parse_eh_frame_entry): Declare.
	(_bfd_elf_end_eh_frame_parsing): Declare.
	(_bfd_elf_write_section_eh_frame_entry): Declare.
	(_bfd_elf_eh_frame_entry_present): Declare.
	(_bfd_elf_section_for_symbol): Declare.
	* elf-eh-frame.c (bfd_elf_discard_eh_frame_entry): New function.
	(bfd_elf_record_eh_frame_entry): New function.
	(_bfd_elf_parse_eh_frame_entry): New function.
	(_bfd_elf_parse_eh_frame): Update hdr_info field references.
	(cmp_eh_frame_hdr): New function.
	(add_eh_frame_hdr_terminator): New function.
	(_bfd_elf_end_eh_frame_parsing): New function.
	(find_merged_cie): Update hdr_info field references.
	(_bfd_elf_discard_section_eh_frame): Likewise.
	(_bfd_elf_discard_section_eh_frame_hdr): Add Compact EH support.
	(_bfd_elf_eh_frame_entry_present): New function.
	(_bfd_elf_maybe_strip_eh_frame_hdr): Add Compact EH support.
	(_bfd_elf_write_section_eh_frame_entry): New function.
	(_bfd_elf_write_section_eh_frame): Update hdr_info field references.
	(_bfd_elf_fixup_eh_frame_hdr): New function.
	(write_compact_eh_frame_hdr): New function.
	(write_dwarf_eh_frame_hdr): New function.
	(_bfd_elf_write_section_eh_frame_hdr): Add Compact EH support.
	* elflink.c (_bfd_elf_section_for_symbol): New function.
	(elf_section_ignore_discarded_relocs): Add Compact EH support.
	(elf_link_input_bfd): Likewise.
	(bfd_elf_final_link): Likewise.
	(_bfd_elf_gc_mark): Likewise.
	(bfd_elf_parse_eh_frame_entries): New function.
	(bfd_elf_gc_sections): Add Compact EH support.
	(bfd_elf_discard_info): Likewise.
	* elfxx-mips.c: Include dwarf2.h.
	(_bfd_mips_elf_compact_eh_encoding): New function.
	(_bfd_mips_elf_cant_unwind_opcode): New function.
	* elfxx-mips.h (_bfd_mips_elf_compact_eh_encoding): Declare.
	(_bfd_mips_elf_cant_unwind_opcode): Declare.
	(elf_backend_compact_eh_encoding): Define.
	(elf_backend_cant_unwind_opcode): Define.
	* elfxx-target.h (elf_backend_compact_eh_encoding): Provide default.
	(elf_backend_cant_unwind_opcode): Provide default.
	(elf_backend_data elfNN_bed): Add elf_backend_compact_eh_encoding and
	elf_backend_cant_unwind_opcode.
	* section.c (SEC_INFO_TYPE_EH_FRAME_ENTRY): Add definition.

	gas/
	* config/tc-alpha.c (all_cfi_sections): Declare.
	(s_alpha_ent): Initialize all_cfi_sections.
	(alpha_elf_md_end): Invoke cfi_set_sections.
	* config/tc-mips.c (md_apply_fix):  Handle BFD_RELOC_NONE.
	(s_ehword): Use BFD_RELOC_32_PCREL.
	(mips_fix_adjustable): Handle BFD_RELOC_32_PCREL.
	(mips_cfi_reloc_for_encoding): New function.
	* tc-mips.h (DWARF2_FDE_RELOC_SIZE): Redefine.
	(DWARF2_FDE_RELOC_ENCODING): Define.
	(tc_cfi_reloc_for_encoding): Define.
	(mips_cfi_reloc_for_encoding): Define.
	(tc_compact_eh_opcode_stop): Define.
	(tc_compact_eh_opcode_pad): Define.
	* doc/as.texinfo: Document Compact EH extensions.
	* doc/internals.texi: Likewise.
	* dw2gencfi.c (EH_FRAME_LINKONCE): Redefine.
	(tc_cfi_reloc_for_encoding): Provide default.
	(compact_eh): Declare.
	(emit_expr_encoded): New function.
	(get_debugseg_name): Add Compact EH support.
	(alloc_debugseg_item): Likewise.
	(cfi_set_sections): New function.
	(dot_cfi_fde_data): New function.
	(dot_cfi_personality_id): New function.
	(dot_cfi_inline_lsda): New function.
	(cfi_pseudo_table): Add cfi_fde_data, cfi_personality_id,
	and cfi_inline_lsda.
	(dot_cfi_personality): Add Compact EH support.
	(dot_cfi_lsda): Likewise.
	(dot_cfi_sections): Likewise.
	(dot_cfi_startproc): Likewise.
	(get_cfi_seg): Likewise.
	(output_compact_unwind_data): New function.
	(output_cfi_insn): Add Compact EH support.
	(output_cie): Likewise.
	(output_fde): Likewise.
	(cfi_finish): Likewise.
	(cfi_emit_eh_header): New function.
	(output_eh_header): New function.
	* dw2gencfi.h (cfi_set_sections): Declare.
	(SUPPORT_COMPACT_EH): Define.
	(MULTIPLE_FRAME_SECTIONS): Define.
	New enumeration to describe the Compact EH header format.
	(fde_entry): Add new fields personality_id, eh_header_type, eh_data_size,
	eh_data, eh_loc and sections.
	(CFI_EMIT_eh_frame, CFI_EMIT_debug_frame, CFI_EMIT_target,
	CFI_EMIT_eh_frame_compact): Define.

2015-05-22  Catherine Moore  <clm@codesourcery.com>
	    Bernd Schmidt <bernds@codesourcery.com>

	gas/testsuite/
	* gas/mips/mips.exp: Run new tests.

	* gas/mips/compact-eh-1.s: New file.
	* gas/mips/compact-eh-2.s: New file.
	* gas/mips/compact-eh-3.s: New file.
	* gas/mips/compact-eh-4.s: New file.
	* gas/mips/compact-eh-5.s: New file.
	* gas/mips/compact-eh-6.s: New file.
	* gas/mips/compact-eh-7.s: New file.
	* gas/mips/compact-eh-eb-1.d: New file.
	* gas/mips/compact-eh-eb-2.d: New file.
	* gas/mips/compact-eh-eb-3.d: New file.
	* gas/mips/compact-eh-eb-4.d: New file.
	* gas/mips/compact-eh-eb-5.d: New file.
	* gas/mips/compact-eh-eb-6.d: New file.
	* gas/mips/compact-eh-eb-7.d: New file.
	* gas/mips/compact-eh-el-1.d: New file.
	* gas/mips/compact-eh-el-2.d: New file.
	* gas/mips/compact-eh-el-3.d: New file.
	* gas/mips/compact-eh-el-4.d: New file.
	* gas/mips/compact-eh-el-5.d: New file.
	* gas/mips/compact-eh-el-6.d: New file.
	* gas/mips/compact-eh-el-7.d: New file.
	* gas/mips/compact-eh-err1.l: New file.
	* gas/mips/compact-eh-err1.s: New file.
	* gas/mips/compact-eh-err2.l: New file.
	* gas/mips/compact-eh-err2.s: New file.

2015-05-22  Catherine Moore  <clm@codesourcery.com>

	include/
	* bfdlink.h: Rename eh_frame_hdr to eh_frame_hdr_type.

2015-05-22  Catherine Moore  <clm@codesourcery.com>
	    Paul Brook <paul@codesourcery.com>

	ld/
	* emultempl/elf32.em (gld${EMULATION_NAME}_after_open):
	Add Compact EH support.
	* scripttempl/elf.sc: Handle .eh_frame_entry and .gnu_extab
	sections.

2015-05-22  Catherine Moore  <clm@codesourcery.com>

	ld/testsuite/
	* ld-mips-elf/compact-eh.ld: New linker script.
	* ld-mips-elf/compact-eh1.d: New.
	* ld-mips-elf/compact-eh1.s: New.
	* ld-mips-elf/compact-eh1a.s: New.
	* ld-mips-elf/compact-eh1b.s: New.
	* ld-mips-elf/compact-eh2.d: New.
	* ld-mips-elf/compact-eh2.s: New.
	* ld-mips-elf/compact-eh3.d: New.
	* ld-mips-elf/compact-eh3.s: New.
	* ld-mips-elf/compact-eh3a.s: New.
	* ld-mips-elf/compact-eh4.d: New.
	* ld-mips-elf/compact-eh5.d: New.
	* ld-mips-elf/compact-eh6.d: New.
	* ld-mips-elf/mips-elf.exp: Run new tests.

3 files changed, 35 insertions, 3 deletions

diff --git a/gas/config/tc-alpha.c b/gas/config/tc-alpha.c
index 30f180f..2a7466a 100644
--- a/gas/config/tc-alpha.c
+++ b/gas/config/tc-alpha.c
@@ -3691,6 +3691,8 @@ static struct alpha_elf_frame_data *all_frame_data;
 static struct alpha_elf_frame_data **plast_frame_data = &all_frame_data;
 static struct alpha_elf_frame_data *cur_frame_data;
 
+extern int all_cfi_sections;
+
 /* Handle the .section pseudo-op.  This is like the usual one, but it
    clears alpha_insn_label and restores auto alignment.  */
 
@@ -3714,6 +3716,8 @@ s_alpha_ent (int dummy ATTRIBUTE_UNUSED)
       char *name, name_end;
       name = input_line_pointer;
       name_end = get_symbol_end ();
+      /* CFI_EMIT_eh_frame is the default.  */
+      all_cfi_sections = CFI_EMIT_eh_frame;
 
       if (! is_name_beginner (*name))
 	{
@@ -4061,6 +4065,7 @@ alpha_elf_md_end (void)
 				      S_GET_VALUE (p->func_sym),
 				      symbol_get_frag (p->func_sym)));
 
+	cfi_set_sections ();
 	cfi_set_return_column (p->ra_regno);
 	cfi_add_CFA_def_cfa_register (30);
 	if (p->fp_regno != 30 || p->mask || p->fmask || p->frame_size)
diff --git a/gas/config/tc-mips.c b/gas/config/tc-mips.c
index 40e38f8..8f2ec65 100644
--- a/gas/config/tc-mips.c
+++ b/gas/config/tc-mips.c
@@ -14840,7 +14840,8 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
 	      || fixP->fx_r_type == BFD_RELOC_MICROMIPS_SUB
 	      || fixP->fx_r_type == BFD_RELOC_VTABLE_INHERIT
 	      || fixP->fx_r_type == BFD_RELOC_VTABLE_ENTRY
-	      || fixP->fx_r_type == BFD_RELOC_MIPS_TLS_DTPREL64);
+	      || fixP->fx_r_type == BFD_RELOC_MIPS_TLS_DTPREL64
+	      || fixP->fx_r_type == BFD_RELOC_NONE);
 
   buf = fixP->fx_frag->fr_literal + fixP->fx_where;
 
@@ -15110,6 +15111,7 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
         S_SET_WEAK (fixP->fx_addsy);
       break;
 
+    case BFD_RELOC_NONE:
     case BFD_RELOC_VTABLE_ENTRY:
       fixP->fx_done = 0;
       break;
@@ -16304,7 +16306,7 @@ s_ehword (int ignore ATTRIBUTE_UNUSED)
   p = frag_more (4);
   md_number_to_chars (p, 0, 4);
   fix_new_exp (frag_now, p - frag_now->fr_literal, 4, &ex, FALSE,
-	       BFD_RELOC_MIPS_EH);
+	       BFD_RELOC_32_PCREL);
 
   demand_empty_rest_of_line ();
 }
@@ -17056,6 +17058,10 @@ mips_fix_adjustable (fixS *fixp)
   if (fixp->fx_addsy == NULL)
     return 1;
 
+  /* Allow relocs used for EH tables.  */
+  if (fixp->fx_r_type == BFD_RELOC_32_PCREL)
+    return 1;
+
   /* If symbol SYM is in a mergeable section, relocations of the form
      SYM + 0 can usually be made section-relative.  The mergeable data
      is then identified by the section offset rather than by the symbol.
@@ -19117,3 +19123,13 @@ md_mips_end (void)
 				Tag_GNU_MIPS_ABI_FP, fpabi);
     }
 }
+
+/*  Returns the relocation type required for a particular CFI encoding.  */
+
+bfd_reloc_code_real_type
+mips_cfi_reloc_for_encoding (int encoding)
+{
+  if (encoding == (DW_EH_PE_sdata4 | DW_EH_PE_pcrel))
+    return BFD_RELOC_32_PCREL;
+  else return BFD_RELOC_NONE;
+}
diff --git a/gas/config/tc-mips.h b/gas/config/tc-mips.h
index dd8350c..6cb3868 100644
--- a/gas/config/tc-mips.h
+++ b/gas/config/tc-mips.h
@@ -176,7 +176,9 @@ extern enum dwarf2_format mips_dwarf2_format (asection *);
 
 extern int mips_dwarf2_addr_size (void);
 #define DWARF2_ADDR_SIZE(bfd) mips_dwarf2_addr_size ()
-#define DWARF2_FDE_RELOC_SIZE mips_dwarf2_addr_size ()
+#define DWARF2_FDE_RELOC_SIZE (compact_eh ? 4 : mips_dwarf2_addr_size ())
+#define DWARF2_FDE_RELOC_ENCODING(enc) \
+  (enc | (compact_eh ? DW_EH_PE_pcrel : 0))
 
 #define TARGET_USE_CFIPOP 1
 
@@ -189,6 +191,15 @@ extern int tc_mips_regname_to_dw2regnum (char *regname);
 #define DWARF2_DEFAULT_RETURN_COLUMN 31
 #define DWARF2_CIE_DATA_ALIGNMENT (-4)
 
+#if defined(OBJ_ELF)
+
+#define tc_cfi_reloc_for_encoding mips_cfi_reloc_for_encoding
+extern bfd_reloc_code_real_type mips_cfi_reloc_for_encoding (int encoding);
+
+#define tc_compact_eh_opcode_stop 0x5c
+#define tc_compact_eh_opcode_pad 0x5f
+
+#endif
 #define DIFF_EXPR_OK
 /* We define DIFF_EXPR_OK because of R_MIPS_PC32, but we have no
    64-bit form for n64 CFIs.  */