libdw: Add dwarf_peel_type. Use it in dwarf_aggregate_size.

Add new function dwarf_peel_type. Some type annotations in DWARF are
specified by modifier tag type wrappers instead of attributes.
For type aliases (typedef) and qualifiers (const, volatile, restrict)
tags dwarf_peel_type follows the DW_AT_type attributes till it finds
a base, user-defined, reference or pointer type DIE.

Use this new function in the backends for return type DIEs (replacing
the existing dwarf_peel_type there) and in dwarf_aggregate_size so
it can provide the sizes for qualified types too. Add a new version
and testcase for the new dwarf_aggregate_size functionality.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

7 files changed, 127 insertions, 4 deletions

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 89b2735f..82cdd883 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,13 @@
+2014-10-06  Mark Wielaard  <mjw@redhat.com>
+
+	* Makefile.am (libdw_a_SOURCES): Add dwarf_peel_type.c.
+	* dwarf_aggregate_size.c (get_type): Use dwarf_peel_type.
+	(aggregate_size): Likewise. Add old and new version.
+	* dwarf_peel_type.c: New file.
+	* libdw.h (dwarf_peel_type): New function declaration.
+	* libdwP.h (dwarf_peel_type): New internal declaration.
+	* libdw.map (ELFUTILS_0.161): New section.
+
 2014-10-15  Petr Machata  <pmachata@redhat.com>
 
 	* libdwP.h (struct Dwarf_Files_s.cu): Drop field.
diff --git a/libdw/Makefile.am b/libdw/Makefile.am
index 2e42a376..859af4d4 100644
--- a/libdw/Makefile.am
+++ b/libdw/Makefile.am
@@ -87,7 +87,7 @@ libdw_a_SOURCES = dwarf_begin.c dwarf_begin_elf.c dwarf_end.c dwarf_getelf.c \
 		  dwarf_aggregate_size.c dwarf_getlocation_implicit_pointer.c \
 		  dwarf_getlocation_die.c dwarf_getlocation_attr.c \
 		  dwarf_getalt.c dwarf_setalt.c dwarf_cu_getdwarf.c \
-		  dwarf_cu_die.c
+		  dwarf_cu_die.c dwarf_peel_type.c
 
 if MAINTAINER_MODE
 BUILT_SOURCES = $(srcdir)/known-dwarf.h
diff --git a/libdw/dwarf_aggregate_size.c b/libdw/dwarf_aggregate_size.c
index 5d23541e..1666e240 100644
--- a/libdw/dwarf_aggregate_size.c
+++ b/libdw/dwarf_aggregate_size.c
@@ -37,8 +37,13 @@
 static Dwarf_Die *
 get_type (Dwarf_Die *die, Dwarf_Attribute *attr_mem, Dwarf_Die *type_mem)
 {
-  return INTUSE(dwarf_formref_die)
+  Dwarf_Die *type = INTUSE(dwarf_formref_die)
     (INTUSE(dwarf_attr_integrate) (die, DW_AT_type, attr_mem), type_mem);
+
+  if (INTUSE(dwarf_peel_type) (type, type) != 0)
+    return NULL;
+
+  return type;
 }
 
 static int
@@ -198,7 +203,6 @@ aggregate_size (Dwarf_Die *die, Dwarf_Word *size, Dwarf_Die *type_mem)
 
   switch (INTUSE(dwarf_tag) (die))
     {
-    case DW_TAG_typedef:
     case DW_TAG_subrange_type:
       return aggregate_size (get_type (die, &attr_mem, type_mem),
 			     size, type_mem); /* Tail call.  */
@@ -225,6 +229,12 @@ dwarf_aggregate_size (die, size)
      Dwarf_Word *size;
 {
   Dwarf_Die type_mem;
+
+  if (INTUSE (dwarf_peel_type) (die, die) != 0)
+    return -1;
+
   return aggregate_size (die, size, &type_mem);
 }
 INTDEF (dwarf_aggregate_size)
+OLD_VERSION (dwarf_aggregate_size, ELFUTILS_0.144)
+NEW_VERSION (dwarf_aggregate_size, ELFUTILS_0.161)
diff --git a/libdw/dwarf_peel_type.c b/libdw/dwarf_peel_type.c
new file mode 100644
index 00000000..a110bc54
--- /dev/null
+++ b/libdw/dwarf_peel_type.c
@@ -0,0 +1,74 @@
+/* Peel type aliases and qualifier tags from a type DIE.
+   Copyright (C) 2014 Red Hat, Inc.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libdwP.h"
+#include <dwarf.h>
+#include <string.h>
+
+
+int
+dwarf_peel_type (die, result)
+     Dwarf_Die *die;
+     Dwarf_Die *result;
+{
+  int tag;
+
+  /* Ignore previous errors.  */
+  if (die == NULL)
+    return -1;
+
+  *result = *die;
+  tag = INTUSE (dwarf_tag) (result);
+  while (tag == DW_TAG_typedef
+	 || tag == DW_TAG_const_type
+	 || tag == DW_TAG_volatile_type
+	 || tag == DW_TAG_restrict_type)
+    {
+      Dwarf_Attribute attr_mem;
+      Dwarf_Attribute *attr = INTUSE (dwarf_attr_integrate) (die, DW_AT_type,
+							     &attr_mem);
+      if (attr == NULL)
+	return 1;
+
+      result = INTUSE (dwarf_formref_die) (attr, result);
+      if (result == NULL)
+	return -1;
+
+      tag = INTUSE (dwarf_tag) (result);
+    }
+
+  if (tag == DW_TAG_invalid)
+    return -1;
+
+  return 0;
+}
+INTDEF(dwarf_peel_type)
diff --git a/libdw/libdw.h b/libdw/libdw.h
index 196d54ae..30364ba1 100644
--- a/libdw/libdw.h
+++ b/libdw/libdw.h
@@ -398,6 +398,24 @@ extern int dwarf_child (Dwarf_Die *die, Dwarf_Die *result)
 extern int dwarf_siblingof (Dwarf_Die *die, Dwarf_Die *result)
      __nonnull_attribute__ (2);
 
+/* For type aliases and qualifier type DIEs follow the DW_AT_type
+   attribute (recursively) and return the underlying type Dwarf_Die.
+   Returns 0 when RESULT contains a Dwarf_Die (possibly equal to the
+   given DIE) that isn't a type alias or qualifier type.  Returns 1
+   when RESULT contains a type alias or qualifier Dwarf_Die that
+   couldn't be peeled further (it doesn't have a DW_TAG_type
+   attribute).  Returns -1 when an error occured.
+
+   The current DWARF specification defines one type alias tag
+   (DW_TAG_typedef) and three qualifier type tags (DW_TAG_const_type,
+   DW_TAG_volatile_type, DW_TAG_restrict_type).  A future version of
+   this function might peel other alias or qualifier type tags if a
+   future DWARF version or GNU extension defines other type aliases or
+   qualifier type tags that don't modify or change the structural
+   layout of the underlying type.  */
+extern int dwarf_peel_type (Dwarf_Die *die, Dwarf_Die *result)
+    __nonnull_attribute__ (2);
+
 /* Check whether the DIE has children.  */
 extern int dwarf_haschildren (Dwarf_Die *die) __nonnull_attribute__ (1);
 
diff --git a/libdw/libdw.map b/libdw/libdw.map
index 55bc5371..0c0ea997 100644
--- a/libdw/libdw.map
+++ b/libdw/libdw.map
@@ -306,4 +306,14 @@ ELFUTILS_0.160 {
   global:
     dwarf_cu_getdwarf;
     dwarf_cu_die;
-} ELFUTILS_0.159;
\ No newline at end of file
+} ELFUTILS_0.159;
+
+ELFUTILS_0.161 {
+  global:
+    dwarf_peel_type;
+
+    # Replaced ELFUTILS_0.144 version.  Both versions point to the
+    # same implementation, but users of the new symbol version can
+    # presume that it uses dwarf_peel_type.
+    dwarf_aggregate_size;
+} ELFUTILS_0.160;
diff --git a/libdw/libdwP.h b/libdw/libdwP.h
index c0f3741c..f0ed316f 100644
--- a/libdw/libdwP.h
+++ b/libdw/libdwP.h
@@ -689,6 +689,7 @@ INTDECL (dwarf_lowpc)
 INTDECL (dwarf_nextcu)
 INTDECL (dwarf_next_unit)
 INTDECL (dwarf_offdie)
+INTDECL (dwarf_peel_type)
 INTDECL (dwarf_ranges)
 INTDECL (dwarf_setalt)
 INTDECL (dwarf_siblingof)