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[PATCH c++/pr87295] -fdebug-types-section ICE

From: Nathan Sidwell <nathan at acm dot org>
To: Richard Biener <richard dot guenther at gmail dot com>
Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
Date: Mon, 17 Sep 2018 07:30:56 -0400
Subject: [PATCH c++/pr87295] -fdebug-types-section ICE

Richard,

this patch makes the ICE go away, but I really don't know if it'scorrect. When cloning the type die I copy die_id, so it is found duringthe (currently ICEing) hash lookup. In this particular testcase weclone the die twice. Once from break_out_comdat_types and once fromcopy_decls_for_unworthy_types. That seems a little strange (but I haveonly the smallest understanding of debug data) As these tracebacks show:


Breakpoint 5, clone_as_declaration (

die=<dw_die_ref 0x7ffff73262d0 DW_TAG_structure_type<parent=0x7ffff73260a0 DW_TAG_compile_unit>>)

    at ../../../src/gcc/dwarf2out.c:8179
8179	  clone->die_id = die->die_id;
(gdb) back

#0 clone_as_declaration (die=<dw_die_ref 0x7ffff73262d0DW_TAG_structure_type <parent=0x7ffff73260a0 DW_TAG_compile_unit>>)

    at ../../../src/gcc/dwarf2out.c:8179

#1 0x0000000000e34faf in generate_skeleton_ancestor_tree(node=0x7fffffffe230) at ../../../src/gcc/dwarf2out.c:8345#2 0x0000000000e351c3 in generate_skeleton_bottom_up(parent=0x7fffffffe230) at ../../../src/gcc/dwarf2out.c:8419

#3  0x0000000000e35291 in generate_skeleton (

die=<dw_die_ref 0x7ffff73262d0 DW_TAG_structure_type<parent=0x7ffff73260a0 DW_TAG_compile_unit>>)

    at ../../../src/gcc/dwarf2out.c:8449

#4 0x0000000000e352ce in remove_child_or_replace_with_skeleton(unit=<dw_die_ref 0x7ffff7326780 DW_TAG_type_unit>,child=<dw_die_ref 0x7ffff73262d0 DW_TAG_structure_type<parent=0x7ffff73260a0 DW_TAG_compile_unit>>,prev=<dw_die_ref 0x7ffff7326550 DW_TAG_pointer_type<parent=0x7ffff73260a0 DW_TAG_compile_unit>>)

    at ../../../src/gcc/dwarf2out.c:8471

#5 0x0000000000e3570a in break_out_comdat_types (die=<dw_die_ref0x7ffff73260a0 DW_TAG_compile_unit>)

    at ../../../src/gcc/dwarf2out.c:8636

#6 0x0000000000e75153 in dwarf2out_early_finish (filename=0x34de9d0"bug.ii") at ../../../src/gcc/dwarf2out.c:32034#7 0x0000000000daa210 in symbol_table::finalize_compilation_unit(this=0x7ffff730d100) at ../../../src/gcc/cgraphunit.c:2783

#8  0x0000000001417ec2 in compile_file () at ../../../src/gcc/toplev.c:480
#9  0x000000000141a90c in do_compile () at ../../../src/gcc/toplev.c:2170

#10 0x000000000141abf8 in toplev::main (this=0x7fffffffe56e, argc=8,argv=0x7fffffffe668) at ../../../src/gcc/toplev.c:2305#11 0x000000000227731e in main (argc=8, argv=0x7fffffffe668) at../../../src/gcc/main.c:39

(gdb) p clone
$2 = <dw_die_ref 0x7ffff7326820 DW_TAG_structure_type>
(gdb) c
Continuing.

Breakpoint 5, clone_as_declaration (die=<dw_die_ref 0x7ffff73262d0DW_TAG_structure_type <parent=0x7ffff7326780 DW_TAG_type_unit>>)

    at ../../../src/gcc/dwarf2out.c:8179
8179	  clone->die_id = die->die_id;
(gdb) p clone
$3 = <dw_die_ref 0x7ffff7326a50 DW_TAG_structure_type>
(gdb) back

#0 clone_as_declaration (die=<dw_die_ref 0x7ffff73262d0DW_TAG_structure_type <parent=0x7ffff7326780 DW_TAG_type_unit>>)

    at ../../../src/gcc/dwarf2out.c:8179

#1 0x0000000000e34dac in copy_ancestor_tree (unit=<dw_die_ref0x7ffff73260a0 DW_TAG_compile_unit>,die=<dw_die_ref 0x7ffff73262d0 DW_TAG_structure_type<parent=0x7ffff7326780 DW_TAG_type_unit>>, decl_table=0x7fffffffe2f0)

    at ../../../src/gcc/dwarf2out.c:8267

#2 0x0000000000e35adb in copy_decls_walk (unit=<dw_die_ref0x7ffff73260a0 DW_TAG_compile_unit>,die=<dw_die_ref 0x7ffff73264b0 DW_TAG_subprogram<parent=0x7ffff7326820 DW_TAG_structure_type>>, decl_table=0x7fffffffe2f0)

    at ../../../src/gcc/dwarf2out.c:8764

#3 0x0000000000e35ba6 in copy_decls_walk (unit=<dw_die_ref0x7ffff73260a0 DW_TAG_compile_unit>,die=<dw_die_ref 0x7ffff7326820 DW_TAG_structure_type<parent=0x7ffff73260a0 DW_TAG_compile_unit>>, decl_table=0x7fffffffe2f0)

    at ../../../src/gcc/dwarf2out.c:8790

#4 0x0000000000e35ba6 in copy_decls_walk (unit=<dw_die_ref0x7ffff73260a0 DW_TAG_compile_unit>,die=<dw_die_ref 0x7ffff73260a0 DW_TAG_compile_unit>,decl_table=0x7fffffffe2f0) at ../../../src/gcc/dwarf2out.c:8790#5 0x0000000000e35c09 in copy_decls_for_unworthy_types(unit=<dw_die_ref 0x7ffff73260a0 DW_TAG_compile_unit>)

    at ../../../src/gcc/dwarf2out.c:8804

#6 0x0000000000e7519a in dwarf2out_early_finish (filename=0x34de9d0"bug.ii") at ../../../src/gcc/dwarf2out.c:32047#7 0x0000000000daa210 in symbol_table::finalize_compilation_unit(this=0x7ffff730d100) at ../../../src/gcc/cgraphunit.c:2783

#8  0x0000000001417ec2 in compile_file () at ../../../src/gcc/toplev.c:480
#9  0x000000000141a90c in do_compile () at ../../../src/gcc/toplev.c:2170

(gdb)


--
Nathan Sidwell

2018-09-17  Nathan Sidwell  <nathan@acm.org>

	PR c++/87295
	* dwarf2out.c (clone_as_declaration): Copy die_id and set
	comdat_type_p as appropriate.

Index: dwarf2out.c
===================================================================
--- dwarf2out.c	(revision 264332)
+++ dwarf2out.c	(working copy)
@@ -8176,8 +8176,12 @@ clone_as_declaration (dw_die_ref die)
         }
     }
 
+  clone->die_id = die->die_id;
   if (die->comdat_type_p)
-    add_AT_die_ref (clone, DW_AT_signature, die);
+    {
+      clone->comdat_type_p = true;
+      add_AT_die_ref (clone, DW_AT_signature, die);
+    }
 
   add_AT_flag (clone, DW_AT_declaration, 1);
   return clone;
Index: testsuite/g++.dg/debug/pr87295.C
===================================================================
--- testsuite/g++.dg/debug/pr87295.C	(revision 0)
+++ testsuite/g++.dg/debug/pr87295.C	(working copy)
@@ -0,0 +1,20 @@
+// PR c++/87295 ICE in dwarf2out
+// { dg-options "-flto -ffat-lto-objects -fdebug-types-section -g -std=gnu++17" }
+
+template<typename _Tp, _Tp __v>
+struct integral_constant
+{
+  static constexpr _Tp value = __v;
+  typedef _Tp value_type;
+  constexpr operator value_type() const noexcept { return value; }
+};
+
+typedef integral_constant<bool, false> false_type;
+
+template<typename...>
+struct __or_;
+
+template<>
+struct __or_<>
+  : public false_type
+{ };

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