DWARF add DW_AT_noreturn on noreturn function subprogram.

This implements the DWARFv5 noreturn proposal:
http://dwarfstd.org/ShowIssue.php?issue=140331.1

TREE_THIS_VOLATILE on a FUNCTION_DECL node means the function does not
return normally. This catches the traditional noreturn GNU attribute,
the C11 _Noreturn keyword and the C++11 [[noreturn]] attribute.

This relies on the DW_AT_noreturn constant defined in the DWARFv5 DRAFT:
http://www.dwarfstd.org/doc/dwarf5.20141029.pdf

gcc/ChangeLog

	* dwarf2out.c (gen_subprogram_die): Add DW_AT_noreturn when the
	function decl has TREE_THIS_VOLATILE.

gcc/testsuite/ChangeLog

	* g++.dg/debug/dwarf2/noreturn-function.C: New test.
	* gcc.dg/debug/dwarf2/noreturn-function-attribute.c: Likewise.
	* gcc.dg/debug/dwarf2/noreturn-function-keyword.c: Likewise.

include/ChangeLog

	* dwarf2.def (DW_AT_noreturn): New DWARF5 attribute.

From-SVN: r218075

8 files changed, 60 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 14fc5b9..e7845c7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-25  Mark Wielaard  <mjw@redhat.com>
+
+	* dwarf2out.c (gen_subprogram_die): Add DW_AT_noreturn when the
+	function decl has TREE_THIS_VOLATILE.
+
 2014-11-26  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/62238
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 3d50ac9..25307d2 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -18336,6 +18336,9 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
       if (DECL_ARTIFICIAL (decl))
 	add_AT_flag (subr_die, DW_AT_artificial, 1);
 
+      if (TREE_THIS_VOLATILE (decl) && (dwarf_version >= 5 || !dwarf_strict))
+	add_AT_flag (subr_die, DW_AT_noreturn, 1);
+
       add_accessibility_attribute (subr_die, decl);
     }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index adc868f..429885c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2014-11-24  Mark Wielaard  <mjw@redhat.com>
+
+	* g++.dg/debug/dwarf2/noreturn-function.C: New test.
+	* gcc.dg/debug/dwarf2/noreturn-function-attribute.c: Likewise.
+	* gcc.dg/debug/dwarf2/noreturn-function-keyword.c: Likewise.
+
 2014-11-26  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/62238
diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/noreturn-function.C b/gcc/testsuite/g++.dg/debug/dwarf2/noreturn-function.C
new file mode 100644
index 0000000..73a0af4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/dwarf2/noreturn-function.C
@@ -0,0 +1,16 @@
+// { dg-do compile }
+// { dg-options "-O -std=c++11 -g -dA -gno-strict-dwarf" }
+// Expect DW_AT_noreturn once in .debug_info and once in .debug_abbrev
+// { dg-final { scan-assembler-times "DW_AT_noreturn" 2 } }
+
+class Foo
+{
+  int i;
+  void bar [[noreturn]] (int j);
+};
+
+void
+Foo::bar (int j)
+{
+  while (1) { ; }
+}
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/noreturn-function-attribute.c b/gcc/testsuite/gcc.dg/debug/dwarf2/noreturn-function-attribute.c
new file mode 100644
index 0000000..7c8924a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/noreturn-function-attribute.c
@@ -0,0 +1,11 @@
+// { dg-do compile }
+// { dg-options "-O -std=c99 -g -dA -gno-strict-dwarf" }
+// Expect DW_AT_noreturn once in .debug_info and once in .debug_abbrev
+// { dg-final { scan-assembler-times "DW_AT_noreturn" 2 } }
+
+void __attribute__ ((noreturn))
+baz (void)
+{
+  while (1) { ; }
+}
+
diff --git a/gcc/testsuite/gcc.dg/debug/dwarf2/noreturn-function-keyword.c b/gcc/testsuite/gcc.dg/debug/dwarf2/noreturn-function-keyword.c
new file mode 100644
index 0000000..ced96d1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/debug/dwarf2/noreturn-function-keyword.c
@@ -0,0 +1,13 @@
+// { dg-do compile }
+// { dg-options "-O -std=c11 -g -dA -gno-strict-dwarf" }
+// Expect DW_AT_noreturn once in .debug_info and once in .debug_abbrev
+// { dg-final { scan-assembler-times "DW_AT_noreturn" 2 } }
+
+_Noreturn void exit (int);
+
+void exit (int i)
+{
+  while (i < 0 || i == 0 || i > 0)
+    ;
+}
+
diff --git a/include/ChangeLog b/include/ChangeLog
index ea7fba6..e73a9a8 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,7 @@
+2014-11-25  Mark Wielaard  <mjw@redhat.com>
+
+	* dwarf2.def (DW_AT_noreturn): New DWARF5 attribute.
+
 2014-11-14  Shinichiro Hamaji  <shinichiro.hamaji@gmail.com>
 
 	* dwarf2.def (DW_AT_APPLE_optimized, DW_AT_APPLE_flags)
diff --git a/include/dwarf2.def b/include/dwarf2.def
index 8ca143c..8533a3e 100644
--- a/include/dwarf2.def
+++ b/include/dwarf2.def
@@ -308,6 +308,8 @@ DW_AT (DW_AT_data_bit_offset, 0x6b)
 DW_AT (DW_AT_const_expr, 0x6c)
 DW_AT (DW_AT_enum_class, 0x6d)
 DW_AT (DW_AT_linkage_name, 0x6e)
+/* DWARF 5.  */
+DW_AT (DW_AT_noreturn, 0x87)
 
 DW_AT_DUP (DW_AT_lo_user, 0x2000) /* Implementation-defined range start.  */
 DW_AT_DUP (DW_AT_hi_user, 0x3fff) /* Implementation-defined range end.  */