[PATCH] Emit DW_AT_inline for C++17 inline variables

[Jakub Jelinek]

Hi!

This also uses the infrastructure of the langhook patch I've sent earlier.
It emits (if not strict dwarf) DW_AT_inline on explicit or implicit inline
variables, and also tweaks dwarf2out so that for inline static data members
we consider in-class declarations as definitions (emit DW_AT_linkage_name
and no DW_AT_declaration) for them.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-10-14  Jakub Jelinek  <jakub@redhat.com>

	* dwarf2out.c (add_linkage_name): Add linkage attribute even for
	DW_TAG_member if it is inline static data member.
	(gen_variable_die): Consider inline static data member's DW_TAG_member
	to be definition rather than declaration.  Add DW_AT_inline attribute
	if needed.
cp/
	* cp-objcp-common.c (cp_decl_dwarf_attribute): Handle DW_AT_inline.
testsuite/
	* g++.dg/debug/dwarf2/inline-var-1.C: New test.

--- gcc/dwarf2out.c.jj	2016-10-14 15:22:57.000000000 +0200
+++ gcc/dwarf2out.c	2016-10-14 16:39:12.226917016 +0200
@@ -18896,7 +18896,10 @@ add_linkage_name (dw_die_ref die, tree d
       && VAR_OR_FUNCTION_DECL_P (decl)
       && TREE_PUBLIC (decl)
       && !(VAR_P (decl) && DECL_REGISTER (decl))
-      && die->die_tag != DW_TAG_member)
+      && (die->die_tag != DW_TAG_member
+	  || (VAR_P (decl)
+	      && (lang_hooks.decls.decl_dwarf_attribute (decl, DW_AT_inline)
+		  != -1))))
     add_linkage_name_raw (die, decl);
 }
 
@@ -21382,6 +21385,20 @@ gen_variable_die (tree decl, tree origin
       return;
     }
 
+  /* For static data members, the declaration (or definition for inline
+     variables) in the class is supposed to have DW_TAG_member tag;
+     the specification if any should still be DW_TAG_variable referencing
+     the DW_TAG_member DIE.  */
+  enum dwarf_tag tag = DW_TAG_variable;
+  if (declaration && class_scope_p (context_die))
+    {
+      tag = DW_TAG_member;
+      /* Inline static data members are defined inside of the class.  */
+      if (lang_hooks.decls.decl_dwarf_attribute (decl_or_origin, DW_AT_inline)
+	  != -1)
+	declaration = false;
+    }
+
   if (old_die)
     {
       if (declaration)
@@ -21414,14 +21431,7 @@ gen_variable_die (tree decl, tree origin
 	  goto gen_variable_die_location;
 	}
     }
-
-  /* For static data members, the declaration in the class is supposed
-     to have DW_TAG_member tag; the specification should still be
-     DW_TAG_variable referencing the DW_TAG_member DIE.  */
-  if (declaration && class_scope_p (context_die))
-    var_die = new_die (DW_TAG_member, context_die, decl);
-  else
-    var_die = new_die (DW_TAG_variable, context_die, decl);
+  var_die = new_die (tag, context_die, decl);
 
   if (origin != NULL)
     origin_die = add_abstract_origin_attribute (var_die, origin);
@@ -21521,6 +21531,17 @@ gen_variable_die (tree decl, tree origin
       && (origin_die == NULL || get_AT (origin_die, DW_AT_const_expr) == NULL)
       && !specialization_p)
     add_AT_flag (var_die, DW_AT_const_expr, 1);
+
+  if (!dwarf_strict)
+    {
+      int inl = lang_hooks.decls.decl_dwarf_attribute (decl_or_origin,
+						       DW_AT_inline);
+      if (inl != -1
+	  && !get_AT (var_die, DW_AT_inline)
+	  && (origin_die == NULL || get_AT (origin_die, DW_AT_inline) == NULL)
+	  && !specialization_p)
+	add_AT_unsigned (var_die, DW_AT_inline, inl);
+    }
 }
 
 /* Generate a DIE to represent a named constant.  */
--- gcc/cp/cp-objcp-common.c.jj	2016-10-14 15:01:27.000000000 +0200
+++ gcc/cp/cp-objcp-common.c	2016-10-14 15:46:14.650303379 +0200
@@ -173,6 +173,16 @@ cp_decl_dwarf_attribute (const_tree decl
 	return 1;
       break;
 
+    case DW_AT_inline:
+      if (VAR_P (decl) && DECL_INLINE_VAR_P (decl))
+	{
+	  if (DECL_VAR_DECLARED_INLINE_P (decl))
+	    return DW_INL_declared_inlined;
+	  else
+	    return DW_INL_inlined;
+	}
+      break;
+
     default:
       break;
     }
--- gcc/testsuite/g++.dg/debug/dwarf2/inline-var-1.C.jj	2016-10-14 16:55:30.345512927 +0200
+++ gcc/testsuite/g++.dg/debug/dwarf2/inline-var-1.C	2016-10-14 16:56:45.704558635 +0200
@@ -0,0 +1,26 @@
+// { dg-do compile }
+// { dg-options "-O -std=c++1z -g -dA -gno-strict-dwarf" }
+// { dg-require-weak "" }
+// { dg-final { scan-assembler-times "0x3\[^\n\r]* DW_AT_inline" 6 } }
+// { dg-final { scan-assembler-times "0x1\[^\n\r]* DW_AT_inline" 2 } }
+// { dg-final { scan-assembler-not " DW_AT_declaration" } }
+// { dg-final { scan-assembler-times " DW_AT_\[^\n\r]*linkage_name" 7 } }
+
+inline int a;
+struct S
+{
+  static inline double b = 4.0;
+  static constexpr int c = 2;
+  static constexpr inline char d = 3;
+} s;
+template <int N>
+inline int e = N;
+int &f = e<2>;
+template <int N>
+struct T
+{
+  static inline double g = 4.0;
+  static constexpr int h = 2;
+  static inline constexpr char i = 3;
+};
+T<5> t;

	Jakub