GAS: Add a return type tag to DWARF DIEs generated for function symbols.

	PR 29517
	* dwarf2dbg.c (GAS_ABBREV_COMP_UNIT): New defined constant.
	(GAS_ABBREV_SUBPROG): New defined constant.
	(GAS_ABBREV_NO_TYPE): New defined constant.
	(out_debug_abbrev): Use the new defined constants when emitting
	abbreviation numbers.  Generate an abbreviation for an unspecified
	type.
	(out_debug_info): Use the new defined constants when referring to
	abbreviations.  Generate a use of the no_type abbreviation.
	Reference the use when generating DIEs for functions.
	* testsuite/gas/elf/dwarf-3-func.d: Update to allow for newly
	extended output from the assembler.
	* testsuite/gas/elf/dwarf-5-func-global.d: Likewise.
	* testsuite/gas/elf/dwarf-5-func-local.d: Likewise.
	* testsuite/gas/elf/dwarf-5-func.d: Likewise.

6 files changed, 82 insertions, 4 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index d3f52bf..e79b986 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,5 +1,23 @@
 2022-08-25  Nick Clifton  <nickc@redhat.com>
 
+	PR 29517
+	* dwarf2dbg.c (GAS_ABBREV_COMP_UNIT): New defined constant.
+	(GAS_ABBREV_SUBPROG): New defined constant.
+	(GAS_ABBREV_NO_TYPE): New defined constant.
+	(out_debug_abbrev): Use the new defined constants when emitting
+	abbreviation numbers.  Generate an abbreviation for an unspecified
+	type.
+	(out_debug_info): Use the new defined constants when referring to
+	abbreviations.  Generate a use of the no_type abbreviation.
+	Reference the use when generating DIEs for functions.
+	* testsuite/gas/elf/dwarf-3-func.d: Update to allow for newly
+	extended output from the assembler.
+	* testsuite/gas/elf/dwarf-5-func-global.d: Likewise.
+	* testsuite/gas/elf/dwarf-5-func-local.d: Likewise.
+	* testsuite/gas/elf/dwarf-5-func.d: Likewise.
+
+2022-08-25  Nick Clifton  <nickc@redhat.com>
+
 	PR 29519
 	* config/tc-aarch64.c (s_unreq): Use find_end_of_line().
 	(s_aarch64_cpu): Likewise.
diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index f346bd6..8f3d528 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -160,6 +160,10 @@
 #define TC_PARSE_CONS_RETURN_NONE BFD_RELOC_NONE
 #endif
 
+#define GAS_ABBREV_COMP_UNIT 1
+#define GAS_ABBREV_SUBPROG   2
+#define GAS_ABBREV_NO_TYPE   3
+
 struct line_entry
 {
   struct line_entry *next;
@@ -2730,7 +2734,7 @@ out_debug_abbrev (segT abbrev_seg,
 
   subseg_set (abbrev_seg, 0);
 
-  out_uleb128 (1);
+  out_uleb128 (GAS_ABBREV_COMP_UNIT);
   out_uleb128 (DW_TAG_compile_unit);
   out_byte (have_efunc || have_lfunc ? DW_CHILDREN_yes : DW_CHILDREN_no);
   if (DWARF2_VERSION < 4)
@@ -2761,7 +2765,7 @@ out_debug_abbrev (segT abbrev_seg,
 
   if (have_efunc || have_lfunc)
     {
-      out_uleb128 (2);
+      out_uleb128 (GAS_ABBREV_SUBPROG);
       out_uleb128 (DW_TAG_subprogram);
       out_byte (DW_CHILDREN_no);
       out_abbrev (DW_AT_name, DW_FORM_strp);
@@ -2776,10 +2780,26 @@ out_debug_abbrev (segT abbrev_seg,
       else
 	/* Any non-zero value other than DW_FORM_flag will do.  */
 	*func_formP = DW_FORM_block;
+
+      /* PR 29517: Provide a return type for the function.  */
+      if (DWARF2_VERSION > 2)
+	out_abbrev (DW_AT_type, DW_FORM_ref_udata);
+
       out_abbrev (DW_AT_low_pc, DW_FORM_addr);
       out_abbrev (DW_AT_high_pc,
 		  DWARF2_VERSION < 4 ? DW_FORM_addr : DW_FORM_udata);
       out_abbrev (0, 0);
+
+      if (DWARF2_VERSION > 2)
+	{
+	  /* PR 29517: We do not actually know the return type of these
+	     functions, so provide an abbrev that uses DWARF's unspecified
+	     type.  */
+	  out_uleb128 (GAS_ABBREV_NO_TYPE);
+	  out_uleb128 (DW_TAG_unspecified_type);
+	  out_byte (DW_CHILDREN_no);
+	  out_abbrev (0, 0);
+	}
     }
 
   /* Terminate the abbreviations for this compilation unit.  */
@@ -2797,6 +2817,7 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
   expressionS exp;
   symbolS *info_end;
   int sizeof_offset;
+  valueT no_type_die = 0;
 
   memset (&exp, 0, sizeof exp);
   sizeof_offset = out_header (info_seg, &exp);
@@ -2825,8 +2846,18 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
       TC_DWARF2_EMIT_OFFSET (section_symbol (abbrev_seg), sizeof_offset);
     }
 
+  if (func_form && DWARF2_VERSION > 2)
+    {
+      /* PR 29517: Generate a DIE for the unspecified type abbrev.
+	 We do it here so that the offset from the start of the
+	 section is fixed.  */
+      subseg_set (info_seg, 0);
+      no_type_die = frag_now_fix_octets ();
+      out_uleb128 (GAS_ABBREV_NO_TYPE);
+    }
+
   /* DW_TAG_compile_unit DIE abbrev */
-  out_uleb128 (1);
+  out_uleb128 (GAS_ABBREV_COMP_UNIT);
 
   /* DW_AT_stmt_list */
   TC_DWARF2_EMIT_OFFSET (section_symbol (line_seg),
@@ -2917,7 +2948,7 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
 	  subseg_set (info_seg, 0);
 
 	  /* DW_TAG_subprogram DIE abbrev */
-	  out_uleb128 (2);
+	  out_uleb128 (GAS_ABBREV_SUBPROG);
 
 	  /* DW_AT_name */
 	  TC_DWARF2_EMIT_OFFSET (name_sym, sizeof_offset);
@@ -2926,6 +2957,11 @@ out_debug_info (segT info_seg, segT abbrev_seg, segT line_seg, segT str_seg,
 	  if (func_form == DW_FORM_flag)
 	    out_byte (S_IS_EXTERNAL (symp));
 
+	  /* PR 29517: Let consumers know that we do not
+	     have return type information for this function.  */
+	  if (DWARF2_VERSION > 2)
+	    out_uleb128 (no_type_die);
+
 	  /* DW_AT_low_pc */
 	  exp.X_op = O_symbol;
 	  exp.X_add_symbol = symp;
diff --git a/gas/testsuite/gas/elf/dwarf-3-func.d b/gas/testsuite/gas/elf/dwarf-3-func.d
index e17dff2..d084518 100644
--- a/gas/testsuite/gas/elf/dwarf-3-func.d
+++ b/gas/testsuite/gas/elf/dwarf-3-func.d
@@ -10,26 +10,32 @@ Contents of the .debug_info section:
  +Version: +3
  +Abbrev Offset: +(0x)?0
  +Pointer Size: .*
+ <0><[0-9a-f]+>: Abbrev Number: 3 \(DW_TAG_unspecified_type\)
+#...
  <0><[0-9a-f]+>: Abbrev Number: 1 \(DW_TAG_compile_unit\)
 #...
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): efunc1
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?0
  +<[0-9a-f]+> +DW_AT_high_pc +: \(addr\) (0x)?2
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): lfunc1
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 0
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?2
  +<[0-9a-f]+> +DW_AT_high_pc +: \(addr\) (0x)?13
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): efunc2
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?13
  +<[0-9a-f]+> +DW_AT_high_pc +: \(addr\) (0x)?35
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): lfunc2
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 0
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?35
  +<[0-9a-f]+> +DW_AT_high_pc +: \(addr\) (0x)?38
  <1><[0-9a-f]+>: Abbrev Number: 0
@@ -42,6 +48,7 @@ Contents of the .debug_abbrev section:
  +2 +DW_TAG_subprogram +\[no children\]
  +DW_AT_name +DW_FORM_strp
  +DW_AT_external +DW_FORM_flag
+ +DW_AT_type +DW_FORM_ref_udata
  +DW_AT_low_pc +DW_FORM_addr
  +DW_AT_high_pc +DW_FORM_addr
  +DW_AT value: 0 +DW_FORM value: 0
diff --git a/gas/testsuite/gas/elf/dwarf-5-func-global.d b/gas/testsuite/gas/elf/dwarf-5-func-global.d
index 03c425d..65c2ab0 100644
--- a/gas/testsuite/gas/elf/dwarf-5-func-global.d
+++ b/gas/testsuite/gas/elf/dwarf-5-func-global.d
@@ -12,16 +12,20 @@ Contents of the .debug_info section:
  +Unit Type: +DW_UT_compile \(1\)
  +Abbrev Offset: +(0x)?0
  +Pointer Size: .*
+ <0><[0-9a-f]+>: Abbrev Number: 3 \(DW_TAG_unspecified_type\)
+#...
  <0><[0-9a-f]+>: Abbrev Number: 1 \(DW_TAG_compile_unit\)
 #...
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): efunc1
  +<[0-9a-f]+> +DW_AT_external +: \(flag_present\) 1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?0
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 2
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): efunc2
  +<[0-9a-f]+> +DW_AT_external +: \(flag_present\) 1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?2
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 34
  <1><[0-9a-f]+>: Abbrev Number: 0
@@ -34,6 +38,7 @@ Contents of the .debug_abbrev section:
  +2 +DW_TAG_subprogram +\[no children\]
  +DW_AT_name +DW_FORM_strp
  +DW_AT_external +DW_FORM_flag_present
+ +DW_AT_type +DW_FORM_ref_udata
  +DW_AT_low_pc +DW_FORM_addr
  +DW_AT_high_pc +DW_FORM_udata
  +DW_AT value: 0 +DW_FORM value: 0
diff --git a/gas/testsuite/gas/elf/dwarf-5-func-local.d b/gas/testsuite/gas/elf/dwarf-5-func-local.d
index ae63515..ac666ea 100644
--- a/gas/testsuite/gas/elf/dwarf-5-func-local.d
+++ b/gas/testsuite/gas/elf/dwarf-5-func-local.d
@@ -12,14 +12,18 @@ Contents of the .debug_info section:
  +Unit Type: +DW_UT_compile \(1\)
  +Abbrev Offset: +(0x)?0
  +Pointer Size: .*
+ <0><[0-9a-f]+>: Abbrev Number: 3 \(DW_TAG_unspecified_type\)
+#...
  <0><[0-9a-f]+>: Abbrev Number: 1 \(DW_TAG_compile_unit\)
 #...
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): lfunc1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?0
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 17
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): lfunc2
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?11
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 3
  <1><[0-9a-f]+>: Abbrev Number: 0
@@ -31,6 +35,7 @@ Contents of the .debug_abbrev section:
 #...
  +2 +DW_TAG_subprogram +\[no children\]
  +DW_AT_name +DW_FORM_strp
+ +DW_AT_type +DW_FORM_ref_udata
  +DW_AT_low_pc +DW_FORM_addr
  +DW_AT_high_pc +DW_FORM_udata
  +DW_AT value: 0 +DW_FORM value: 0
diff --git a/gas/testsuite/gas/elf/dwarf-5-func.d b/gas/testsuite/gas/elf/dwarf-5-func.d
index 0d331c6..612c9f2 100644
--- a/gas/testsuite/gas/elf/dwarf-5-func.d
+++ b/gas/testsuite/gas/elf/dwarf-5-func.d
@@ -12,26 +12,32 @@ Contents of the .debug_info section:
  +Unit Type: +DW_UT_compile \(1\)
  +Abbrev Offset: +(0x)?0
  +Pointer Size: .*
+ <0><[0-9a-f]+>: Abbrev Number: 3 \(DW_TAG_unspecified_type\)
+#...
  <0><[0-9a-f]+>: Abbrev Number: 1 \(DW_TAG_compile_unit\)
 #...
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): efunc1
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?0
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 2
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): lfunc1
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 0
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?2
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 17
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): efunc2
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 1
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?13
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 34
  <1><[0-9a-f]+>: Abbrev Number: 2 \(DW_TAG_subprogram\)
  +<[0-9a-f]+> +DW_AT_name +: \(strp\) \(offset: (0x)?[0-9a-f]+\): lfunc2
  +<[0-9a-f]+> +DW_AT_external +: \(flag\) 0
+ +<[0-9a-f]+> +DW_AT_type +: \(ref_udata\) <0x.>
  +<[0-9a-f]+> +DW_AT_low_pc +: \(addr\) (0x)?35
  +<[0-9a-f]+> +DW_AT_high_pc +: \(udata\) 3
  <1><[0-9a-f]+>: Abbrev Number: 0
@@ -44,6 +50,7 @@ Contents of the .debug_abbrev section:
  +2 +DW_TAG_subprogram +\[no children\]
  +DW_AT_name +DW_FORM_strp
  +DW_AT_external +DW_FORM_flag
+ +DW_AT_type +DW_FORM_ref_udata
  +DW_AT_low_pc +DW_FORM_addr
  +DW_AT_high_pc +DW_FORM_udata
  +DW_AT value: 0 +DW_FORM value: 0