btrace, frame: fix crash in get_frame_type

In skip_artificial_frames we repeatedly call get_prev_frame_always until we get
a non-inline and non-tailcall frame assuming that there must be such a frame
eventually.

For record targets, however, we may have a frame chain that consists only of
artificial frames.  This leads to a crash in get_frame_type when dereferencing a
NULL frame pointer.

Change skip_artificial_frames and skip_tailcall_frames to return NULL in such a
case and modify each caller to cope with a NULL return.

In frame_unwind_caller_pc and frame_unwind_caller_arch, we simply assert that
the returned value is not NULL.  Their caller was supposed to check
frame_unwind_caller_id before calling those functions.

In other cases, we thrown an error.

In infcmd further move the skip_tailcall_frames call to the forward-stepping
case since we don't need a frame for reverse execution and we don't want to fail
because of that.  Reverse-finish does make sense for a tailcall frame.

gdb/
	* frame.h (skip_tailcall_frames): Update comment.
	* frame.c (skip_artificial_frames, skip_tailcall_frames): Return NULL
	if only	artificial frames are found.  Update comment.
	(frame_unwind_caller_id): Handle NULL return.
	(frame_unwind_caller_pc, frame_unwind_caller_arch): Assert that
	skip_artificial_frames does not return NULL.
	(frame_pop): Add an error if only tailcall frames are found.
	* infcmd.c (finish_command): Move skip_tailcall_frames call into forward-
	execution case.  Add an error if only tailcall frames are found.

testsuite/
	* gdb.btrace/tailcall-only.exp: New.
	* gdb.btrace/tailcall-only.c: New.
	* gdb.btrace/x86_64-tailcall-only.S: New.
	* gdb.btrace/i686-tailcall-only.S: New.

gdb/ChangeLog

@@ -1,3 +1,16 @@
+2016-02-12  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* frame.h (skip_tailcall_frames): Update comment.
+	* frame.c (skip_artificial_frames, skip_tailcall_frames): Return NULL
+	if only artificial frames are found.  Update comment.
+	(frame_unwind_caller_id): Handle NULL return.
+	(frame_unwind_caller_pc, frame_unwind_caller_arch): Assert that
+	skip_artificial_frames does not return NULL.
+	(frame_pop): Add an error if only tailcall frames are found.
+	* infcmd.c (finish_command): Move skip_tailcall_frames call into
+	forward-execution case.  Add an error if only tailcall frames are
+	found.
+
 2016-02-12  Markus Metzger  <markus.t.metzger@intel.com>
 
 	* stack.c (frame_info): Check frame_unwind_caller_id.

gdb/frame.c

@@ -420,7 +420,8 @@ fprint_frame (struct ui_file *file, struct frame_info *fi)
 
 /* Given FRAME, return the enclosing frame as found in real frames read-in from
    inferior memory.  Skip any previous frames which were made up by GDB.
-   Return the original frame if no immediate previous frames exist.  */
+   Return FRAME if FRAME is a non-artificial frame.
+   Return NULL if FRAME is the start of an artificial-only chain.  */
 
 static struct frame_info *
 skip_artificial_frames (struct frame_info *frame)
@@ -428,12 +429,17 @@ skip_artificial_frames (struct frame_info *frame)
   /* Note we use get_prev_frame_always, and not get_prev_frame.  The
      latter will truncate the frame chain, leading to this function
      unintentionally returning a null_frame_id (e.g., when the user
-     sets a backtrace limit).  This is safe, because as these frames
+     sets a backtrace limit).
-     are made up by GDB, there must be a real frame in the chain
+
-     below.  */
+     Note that for record targets we may get a frame chain that consists
+     of artificial frames only.  */
   while (get_frame_type (frame) == INLINE_FRAME
 	 || get_frame_type (frame) == TAILCALL_FRAME)
-    frame = get_prev_frame_always (frame);
+    {
+      frame = get_prev_frame_always (frame);
+      if (frame == NULL)
+	break;
+    }
 
   return frame;
 }
@@ -444,7 +450,13 @@ struct frame_info *
 skip_tailcall_frames (struct frame_info *frame)
 {
   while (get_frame_type (frame) == TAILCALL_FRAME)
-    frame = get_prev_frame (frame);
+    {
+      /* Note that for record targets we may get a frame chain that consists of
+	 tailcall frames only.  */
+      frame = get_prev_frame (frame);
+      if (frame == NULL)
+	break;
+    }
 
   return frame;
 }
@@ -507,6 +519,9 @@ frame_unwind_caller_id (struct frame_info *next_frame)
      requests the frame ID of "main()"s caller.  */
 
   next_frame = skip_artificial_frames (next_frame);
+  if (next_frame == NULL)
+    return null_frame_id;
+
   this_frame = get_prev_frame_always (next_frame);
   if (this_frame)
     return get_frame_id (skip_artificial_frames (this_frame));
@@ -880,7 +895,14 @@ frame_unwind_pc (struct frame_info *this_frame)
 CORE_ADDR
 frame_unwind_caller_pc (struct frame_info *this_frame)
 {
-  return frame_unwind_pc (skip_artificial_frames (this_frame));
+  this_frame = skip_artificial_frames (this_frame);
+
+  /* We must have a non-artificial frame.  The caller is supposed to check
+     the result of frame_unwind_caller_id (), which returns NULL_FRAME_ID
+     in this case.  */
+  gdb_assert (this_frame != NULL);
+
+  return frame_unwind_pc (this_frame);
 }
 
 int
@@ -985,6 +1007,9 @@ frame_pop (struct frame_info *this_frame)
      entering THISFRAME.  */
   prev_frame = skip_tailcall_frames (prev_frame);
 
+  if (prev_frame == NULL)
+    error (_("Cannot find the caller frame."));
+
   /* Make a copy of all the register values unwound from this frame.
      Save them in a scratch buffer so that there isn't a race between
      trying to extract the old values from the current regcache while
@@ -2571,7 +2596,14 @@ frame_unwind_arch (struct frame_info *next_frame)
 struct gdbarch *
 frame_unwind_caller_arch (struct frame_info *next_frame)
 {
-  return frame_unwind_arch (skip_artificial_frames (next_frame));
+  next_frame = skip_artificial_frames (next_frame);
+
+  /* We must have a non-artificial frame.  The caller is supposed to check
+     the result of frame_unwind_caller_id (), which returns NULL_FRAME_ID
+     in this case.  */
+  gdb_assert (next_frame != NULL);
+
+  return frame_unwind_arch (next_frame);
 }
 
 /* Gets the language of FRAME.  */

gdb/frame.h

@@ -821,7 +821,8 @@ extern int frame_unwinder_is (struct frame_info *fi,
 extern enum language get_frame_language (struct frame_info *frame);
 
 /* Return the first non-tailcall frame above FRAME or FRAME if it is not a
-   tailcall frame.  */
+   tailcall frame.  Return NULL if FRAME is the start of a tailcall-only
+   chain.  */
 
 extern struct frame_info *skip_tailcall_frames (struct frame_info *frame);
 

gdb/infcmd.c

@@ -2000,10 +2000,6 @@ finish_command (char *arg, int from_tty)
       return;
     }
 
-  /* Ignore TAILCALL_FRAME type frames, they were executed already before
-     entering THISFRAME.  */
-  frame = skip_tailcall_frames (frame);
-
   /* Find the function we will return from.  */
 
   sm->function = find_pc_function (get_frame_pc (get_selected_frame (NULL)));
@@ -2030,7 +2026,16 @@ finish_command (char *arg, int from_tty)
   if (execution_direction == EXEC_REVERSE)
     finish_backward (sm);
   else
-    finish_forward (sm, frame);
+    {
+      /* Ignore TAILCALL_FRAME type frames, they were executed already before
+	 entering THISFRAME.  */
+      frame = skip_tailcall_frames (frame);
+
+      if (frame == NULL)
+	error (_("Cannot find the caller frame."));
+
+      finish_forward (sm, frame);
+    }
 }
 
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2016-02-12  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* gdb.btrace/tailcall-only.exp: New.
+	* gdb.btrace/tailcall-only.c: New.
+	* gdb.btrace/x86_64-tailcall-only.S: New.
+	* gdb.btrace/i686-tailcall-only.S: New.
+
 2016-02-11  Pedro Alves  <palves@redhat.com>
 
 	* README (Parallel testing): Add missing double quotes.

gdb/testsuite/gdb.btrace/i686-tailcall-only.S

@@ -0,0 +1,447 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+   This file has been generated using:
+   gcc -m32 -march=i686 -S -O2 -dA -g tailcall-only.c -o i686-tailcall-only.S
+ */
+
+	.file	"tailcall-only.c"
+	.text
+.Ltext0:
+	.p2align 4,,15
+	.type	bar_1, @function
+bar_1:
+.LFB0:
+	.file 1 "tailcall-only.c"
+	# tailcall-only.c:22
+	.loc 1 22 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:24
+	.loc 1 24 0
+	movl	$42, %eax
+# SUCC: EXIT [100.0%]
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	bar_1, .-bar_1
+	.p2align 4,,15
+	.type	bar, @function
+bar:
+.LFB1:
+	# tailcall-only.c:28
+	.loc 1 28 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:29
+	.loc 1 29 0
+	jmp	bar_1
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+.LVL0:
+	.cfi_endproc
+.LFE1:
+	.size	bar, .-bar
+	.p2align 4,,15
+	.type	foo_1, @function
+foo_1:
+.LFB2:
+	# tailcall-only.c:34
+	.loc 1 34 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:35
+	.loc 1 35 0
+	jmp	bar
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+.LVL1:
+	.cfi_endproc
+.LFE2:
+	.size	foo_1, .-foo_1
+	.p2align 4,,15
+	.type	foo, @function
+foo:
+.LFB3:
+	# tailcall-only.c:40
+	.loc 1 40 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:41
+	.loc 1 41 0
+	jmp	foo_1
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+.LVL2:
+	.cfi_endproc
+.LFE3:
+	.size	foo, .-foo
+	.section	.text.startup,"ax",@progbits
+	.p2align 4,,15
+	.globl	main
+	.type	main, @function
+main:
+.LFB4:
+	# tailcall-only.c:46
+	.loc 1 46 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:49
+	.loc 1 49 0
+	call	foo
+.LVL3:
+	# tailcall-only.c:50
+	.loc 1 50 0
+	addl	$1, %eax
+.LVL4:
+# SUCC: EXIT [100.0%]
+	# tailcall-only.c:53
+	.loc 1 53 0
+	ret
+	.cfi_endproc
+.LFE4:
+	.size	main, .-main
+	.text
+.Letext0:
+	.section	.debug_info,"",@progbits
+.Ldebug_info0:
+	.long	0xd5	# Length of Compilation Unit Info
+	.value	0x4	# DWARF version number
+	.long	.Ldebug_abbrev0	# Offset Into Abbrev. Section
+	.byte	0x4	# Pointer Size (in bytes)
+	.uleb128 0x1	# (DIE (0xb) DW_TAG_compile_unit)
+	.long	.LASF1	# DW_AT_producer: "GNU C 4.8.3 20140911 (Red Hat 4.8.3-9) -m32 -march=i686 -g -O2"
+	.byte	0x1	# DW_AT_language
+	.long	.LASF2	# DW_AT_name: "tailcall-only.c"
+	.long	.LASF3	# DW_AT_comp_dir: ""
+	.long	.Ldebug_ranges0+0	# DW_AT_ranges
+	.long	0	# DW_AT_low_pc
+	.long	.Ldebug_line0	# DW_AT_stmt_list
+	.uleb128 0x2	# (DIE (0x25) DW_TAG_subprogram)
+	.long	.LASF4	# DW_AT_name: "bar_1"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x15	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x3a	# DW_AT_type
+	.long	.LFB0	# DW_AT_low_pc
+	.long	.LFE0-.LFB0	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.uleb128 0x3	# (DIE (0x3a) DW_TAG_base_type)
+	.byte	0x4	# DW_AT_byte_size
+	.byte	0x5	# DW_AT_encoding
+	.ascii "int\0"	# DW_AT_name
+	.uleb128 0x4	# (DIE (0x41) DW_TAG_subprogram)
+	.ascii "bar\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x1b	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x3a	# DW_AT_type
+	.long	.LFB1	# DW_AT_low_pc
+	.long	.LFE1-.LFB1	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.long	0x64	# DW_AT_sibling
+	.uleb128 0x5	# (DIE (0x5a) DW_TAG_GNU_call_site)
+	.long	.LVL0	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	0x25	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0x41
+	.uleb128 0x6	# (DIE (0x64) DW_TAG_subprogram)
+	.long	.LASF0	# DW_AT_name: "foo_1"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x21	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x3a	# DW_AT_type
+	.long	.LFB2	# DW_AT_low_pc
+	.long	.LFE2-.LFB2	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.long	0x87	# DW_AT_sibling
+	.uleb128 0x5	# (DIE (0x7d) DW_TAG_GNU_call_site)
+	.long	.LVL1	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	0x41	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0x64
+	.uleb128 0x4	# (DIE (0x87) DW_TAG_subprogram)
+	.ascii "foo\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x27	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x3a	# DW_AT_type
+	.long	.LFB3	# DW_AT_low_pc
+	.long	.LFE3-.LFB3	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.long	0xaa	# DW_AT_sibling
+	.uleb128 0x5	# (DIE (0xa0) DW_TAG_GNU_call_site)
+	.long	.LVL2	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	0x64	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0x87
+	.uleb128 0x7	# (DIE (0xaa) DW_TAG_subprogram)
+			# DW_AT_external
+	.long	.LASF5	# DW_AT_name: "main"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x2d	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x3a	# DW_AT_type
+	.long	.LFB4	# DW_AT_low_pc
+	.long	.LFE4-.LFB4	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.uleb128 0x8	# (DIE (0xbf) DW_TAG_variable)
+	.long	.LASF6	# DW_AT_name: "answer"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x2f	# DW_AT_decl_line
+	.long	0x3a	# DW_AT_type
+	.long	.LLST0	# DW_AT_location
+	.uleb128 0x9	# (DIE (0xce) DW_TAG_GNU_call_site)
+	.long	.LVL3	# DW_AT_low_pc
+	.long	0x87	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0xaa
+	.byte	0	# end of children of DIE 0xb
+	.section	.debug_abbrev,"",@progbits
+.Ldebug_abbrev0:
+	.uleb128 0x1	# (abbrev code)
+	.uleb128 0x11	# (TAG: DW_TAG_compile_unit)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x25	# (DW_AT_producer)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x13	# (DW_AT_language)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x1b	# (DW_AT_comp_dir)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x55	# (DW_AT_ranges)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x10	# (DW_AT_stmt_list)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.byte	0
+	.byte	0
+	.uleb128 0x2	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0	# DW_children_no
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x6	# (DW_FORM_data4)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.byte	0
+	.byte	0
+	.uleb128 0x3	# (abbrev code)
+	.uleb128 0x24	# (TAG: DW_TAG_base_type)
+	.byte	0	# DW_children_no
+	.uleb128 0xb	# (DW_AT_byte_size)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3e	# (DW_AT_encoding)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0x8	# (DW_FORM_string)
+	.byte	0
+	.byte	0
+	.uleb128 0x4	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0x8	# (DW_FORM_string)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x6	# (DW_FORM_data4)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x1	# (DW_AT_sibling)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0x5	# (abbrev code)
+	.uleb128 0x4109	# (TAG: DW_TAG_GNU_call_site)
+	.byte	0	# DW_children_no
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x2115	# (DW_AT_GNU_tail_call)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x31	# (DW_AT_abstract_origin)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0x6	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x6	# (DW_FORM_data4)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x1	# (DW_AT_sibling)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0x7	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x3f	# (DW_AT_external)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x6	# (DW_FORM_data4)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.byte	0
+	.byte	0
+	.uleb128 0x8	# (abbrev code)
+	.uleb128 0x34	# (TAG: DW_TAG_variable)
+	.byte	0	# DW_children_no
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x2	# (DW_AT_location)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.byte	0
+	.byte	0
+	.uleb128 0x9	# (abbrev code)
+	.uleb128 0x4109	# (TAG: DW_TAG_GNU_call_site)
+	.byte	0	# DW_children_no
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x31	# (DW_AT_abstract_origin)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_loc,"",@progbits
+.Ldebug_loc0:
+.LLST0:
+	.long	.LVL3	# Location list begin address (*.LLST0)
+	.long	.LVL4	# Location list end address (*.LLST0)
+	.value	0x3	# Location expression size
+	.byte	0x70	# DW_OP_breg0
+	.sleb128 1
+	.byte	0x9f	# DW_OP_stack_value
+	.long	.LVL4	# Location list begin address (*.LLST0)
+	.long	.LFE4	# Location list end address (*.LLST0)
+	.value	0x1	# Location expression size
+	.byte	0x50	# DW_OP_reg0
+	.long	0	# Location list terminator begin (*.LLST0)
+	.long	0	# Location list terminator end (*.LLST0)
+	.section	.debug_aranges,"",@progbits
+	.long	0x24	# Length of Address Ranges Info
+	.value	0x2	# DWARF Version
+	.long	.Ldebug_info0	# Offset of Compilation Unit Info
+	.byte	0x4	# Size of Address
+	.byte	0	# Size of Segment Descriptor
+	.value	0	# Pad to 8 byte boundary
+	.value	0
+	.long	.Ltext0	# Address
+	.long	.Letext0-.Ltext0	# Length
+	.long	.LFB4	# Address
+	.long	.LFE4-.LFB4	# Length
+	.long	0
+	.long	0
+	.section	.debug_ranges,"",@progbits
+.Ldebug_ranges0:
+	.long	.Ltext0	# Offset 0
+	.long	.Letext0
+	.long	.LFB4	# Offset 0x8
+	.long	.LFE4
+	.long	0
+	.long	0
+	.section	.debug_line,"",@progbits
+.Ldebug_line0:
+	.section	.debug_str,"MS",@progbits,1
+.LASF4:
+	.string	"bar_1"
+.LASF2:
+	.string	"tailcall-only.c"
+.LASF1:
+	.string	"GNU C 4.8.3 20140911 (Red Hat 4.8.3-9) -m32 -march=i686 -g -O2"
+.LASF6:
+	.string	"answer"
+.LASF5:
+	.string	"main"
+.LASF3:
+	.string	""
+.LASF0:
+	.string	"foo_1"
+	.ident	"GCC: (GNU) 4.8.3 20140911 (Red Hat 4.8.3-9)"
+	.section	.note.GNU-stack,"",@progbits

gdb/testsuite/gdb.btrace/tailcall-only.c

@@ -0,0 +1,53 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   Contributed by Intel Corp. <markus.t.metzger@intel.com>
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+static __attribute__ ((noinline)) int
+bar_1 (void)
+{
+  return 42;
+}
+
+static __attribute__ ((noinline)) int
+bar (void)
+{
+  return bar_1 ();
+}
+
+static __attribute__ ((noinline)) int
+foo_1 (void)
+{
+  return bar ();
+}
+
+static __attribute__ ((noinline)) int
+foo (void)
+{
+  return foo_1 ();
+}
+
+int
+main (void)
+{
+  int answer;
+
+  answer = foo ();
+  answer += 1;
+
+  return answer;
+}

gdb/testsuite/gdb.btrace/tailcall-only.exp

@@ -0,0 +1,97 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2016 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+#
+# This is a variant of tailcall.exp where the entire trace contains only tail
+# calls.  This used to cause a crash in get_frame_type.
+#
+
+# check for btrace support
+if { [skip_btrace_tests] } { return -1 }
+
+# This test requires the compiler to generate a tail call.  To guarantee that
+# we always get one, we use an assembly source file.
+#
+# We use different assembly sources based on the target architecture.
+#
+# Luckily, they are similar enough that a single test script can handle
+# both.
+set opts {}
+if [info exists COMPILE] {
+    # make check RUNTESTFLAGS="gdb.btrace/tailcall-only.exp COMPILE=1"
+    standard_testfile tailcall-only.c
+    lappend opts debug optimize=-O2
+} elseif {[istarget "x86_64-*-*"]} {
+	standard_testfile x86_64-tailcall-only.S
+} elseif {[istarget "i?86-*-*"]} {
+	standard_testfile i686-tailcall-only.S
+} else {
+    verbose "Skipping ${testfile}."
+    return
+}
+
+if [prepare_for_testing tailcall-only.exp $testfile $srcfile $opts] {
+    return -1
+}
+if ![runto_main] {
+    return -1
+}
+
+# we want to see the full trace for this test
+gdb_test_no_output "set record function-call-history-size 0"
+
+# trace foo
+gdb_test "step" ".*" "prepare for recording"
+gdb_test_no_output "record btrace"
+gdb_test "stepi 4" ".*" "record branch trace"
+
+# for debugging
+gdb_test "info record" ".*"
+
+# show the branch trace with calls indented
+gdb_test "record function-call-history /c 1" [multi_line \
+  "1\tfoo" \
+  "2\t  foo_1" \
+  "3\t    bar" \
+  "4\t      bar_1"
+  ] "function-call-history"
+
+# We can step
+gdb_test "record goto begin" ".*foo.*"
+gdb_test "stepi" ".*foo_1.*" "step into foo_1"
+gdb_test "step" ".*bar.*" "step into bar"
+gdb_test "stepi" ".*bar_1.*" "step into bar_1"
+
+# We can neither finish nor return.
+gdb_test "finish" "Cannot find the caller frame.*"
+gdb_test_multiple "return" "return" {
+  -re "Make .* return now.*y or n. $" {
+    send_gdb "y\n"
+    exp_continue
+  }
+  -re "Cannot find the caller frame.*$gdb_prompt $" {
+    pass "return"
+  }
+}
+
+# But we can reverse-finish
+gdb_test "reverse-finish" ".*bar.*"
+gdb_test "reverse-step" ".*foo_1.*"
+
+# Info frame isn't useful but doesn't crash as it used to.
+gdb_test "up" ".*foo.*"
+gdb_test "info frame" ".*"

gdb/testsuite/gdb.btrace/x86_64-tailcall-only.S

@@ -0,0 +1,446 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+   This file has been generated using:
+   gcc -S -O2 -dA -g tailcall-only.c -o x86_64-tailcall-only.S  */
+
+	.file	"tailcall-only.c"
+	.text
+.Ltext0:
+	.p2align 4,,15
+	.type	bar_1, @function
+bar_1:
+.LFB0:
+	.file 1 "tailcall-only.c"
+	# tailcall-only.c:22
+	.loc 1 22 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:24
+	.loc 1 24 0
+	movl	$42, %eax
+# SUCC: EXIT [100.0%]
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	bar_1, .-bar_1
+	.p2align 4,,15
+	.type	bar, @function
+bar:
+.LFB1:
+	# tailcall-only.c:28
+	.loc 1 28 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:29
+	.loc 1 29 0
+	jmp	bar_1
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+.LVL0:
+	.cfi_endproc
+.LFE1:
+	.size	bar, .-bar
+	.p2align 4,,15
+	.type	foo_1, @function
+foo_1:
+.LFB2:
+	# tailcall-only.c:34
+	.loc 1 34 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:35
+	.loc 1 35 0
+	jmp	bar
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+.LVL1:
+	.cfi_endproc
+.LFE2:
+	.size	foo_1, .-foo_1
+	.p2align 4,,15
+	.type	foo, @function
+foo:
+.LFB3:
+	# tailcall-only.c:40
+	.loc 1 40 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:41
+	.loc 1 41 0
+	jmp	foo_1
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+.LVL2:
+	.cfi_endproc
+.LFE3:
+	.size	foo, .-foo
+	.section	.text.startup,"ax",@progbits
+	.p2align 4,,15
+	.globl	main
+	.type	main, @function
+main:
+.LFB4:
+	# tailcall-only.c:46
+	.loc 1 46 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# tailcall-only.c:49
+	.loc 1 49 0
+	call	foo
+.LVL3:
+	# tailcall-only.c:50
+	.loc 1 50 0
+	addl	$1, %eax
+.LVL4:
+# SUCC: EXIT [100.0%]
+	# tailcall-only.c:53
+	.loc 1 53 0
+	ret
+	.cfi_endproc
+.LFE4:
+	.size	main, .-main
+	.text
+.Letext0:
+	.section	.debug_info,"",@progbits
+.Ldebug_info0:
+	.long	0x111	# Length of Compilation Unit Info
+	.value	0x4	# DWARF version number
+	.long	.Ldebug_abbrev0	# Offset Into Abbrev. Section
+	.byte	0x8	# Pointer Size (in bytes)
+	.uleb128 0x1	# (DIE (0xb) DW_TAG_compile_unit)
+	.long	.LASF1	# DW_AT_producer: "GNU C 4.8.3 20140911 (Red Hat 4.8.3-9) -mtune=generic -march=x86-64 -g -O2"
+	.byte	0x1	# DW_AT_language
+	.long	.LASF2	# DW_AT_name: "tailcall-only.c"
+	.long	.LASF3	# DW_AT_comp_dir: ""
+	.long	.Ldebug_ranges0+0	# DW_AT_ranges
+	.quad	0	# DW_AT_low_pc
+	.long	.Ldebug_line0	# DW_AT_stmt_list
+	.uleb128 0x2	# (DIE (0x29) DW_TAG_subprogram)
+	.long	.LASF4	# DW_AT_name: "bar_1"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x15	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x46	# DW_AT_type
+	.quad	.LFB0	# DW_AT_low_pc
+	.quad	.LFE0-.LFB0	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.uleb128 0x3	# (DIE (0x46) DW_TAG_base_type)
+	.byte	0x4	# DW_AT_byte_size
+	.byte	0x5	# DW_AT_encoding
+	.ascii "int\0"	# DW_AT_name
+	.uleb128 0x4	# (DIE (0x4d) DW_TAG_subprogram)
+	.ascii "bar\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x1b	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x46	# DW_AT_type
+	.quad	.LFB1	# DW_AT_low_pc
+	.quad	.LFE1-.LFB1	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.long	0x7c	# DW_AT_sibling
+	.uleb128 0x5	# (DIE (0x6e) DW_TAG_GNU_call_site)
+	.quad	.LVL0	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	0x29	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0x4d
+	.uleb128 0x6	# (DIE (0x7c) DW_TAG_subprogram)
+	.long	.LASF0	# DW_AT_name: "foo_1"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x21	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x46	# DW_AT_type
+	.quad	.LFB2	# DW_AT_low_pc
+	.quad	.LFE2-.LFB2	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.long	0xab	# DW_AT_sibling
+	.uleb128 0x5	# (DIE (0x9d) DW_TAG_GNU_call_site)
+	.quad	.LVL1	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	0x4d	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0x7c
+	.uleb128 0x4	# (DIE (0xab) DW_TAG_subprogram)
+	.ascii "foo\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x27	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x46	# DW_AT_type
+	.quad	.LFB3	# DW_AT_low_pc
+	.quad	.LFE3-.LFB3	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.long	0xda	# DW_AT_sibling
+	.uleb128 0x5	# (DIE (0xcc) DW_TAG_GNU_call_site)
+	.quad	.LVL2	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	0x7c	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0xab
+	.uleb128 0x7	# (DIE (0xda) DW_TAG_subprogram)
+			# DW_AT_external
+	.long	.LASF5	# DW_AT_name: "main"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x2d	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	0x46	# DW_AT_type
+	.quad	.LFB4	# DW_AT_low_pc
+	.quad	.LFE4-.LFB4	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.uleb128 0x8	# (DIE (0xf7) DW_TAG_variable)
+	.long	.LASF6	# DW_AT_name: "answer"
+	.byte	0x1	# DW_AT_decl_file (tailcall-only.c)
+	.byte	0x2f	# DW_AT_decl_line
+	.long	0x46	# DW_AT_type
+	.long	.LLST0	# DW_AT_location
+	.uleb128 0x9	# (DIE (0x106) DW_TAG_GNU_call_site)
+	.quad	.LVL3	# DW_AT_low_pc
+	.long	0xab	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0xda
+	.byte	0	# end of children of DIE 0xb
+	.section	.debug_abbrev,"",@progbits
+.Ldebug_abbrev0:
+	.uleb128 0x1	# (abbrev code)
+	.uleb128 0x11	# (TAG: DW_TAG_compile_unit)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x25	# (DW_AT_producer)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x13	# (DW_AT_language)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x1b	# (DW_AT_comp_dir)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x55	# (DW_AT_ranges)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x10	# (DW_AT_stmt_list)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.byte	0
+	.byte	0
+	.uleb128 0x2	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0	# DW_children_no
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x7	# (DW_FORM_data8)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.byte	0
+	.byte	0
+	.uleb128 0x3	# (abbrev code)
+	.uleb128 0x24	# (TAG: DW_TAG_base_type)
+	.byte	0	# DW_children_no
+	.uleb128 0xb	# (DW_AT_byte_size)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3e	# (DW_AT_encoding)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0x8	# (DW_FORM_string)
+	.byte	0
+	.byte	0
+	.uleb128 0x4	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0x8	# (DW_FORM_string)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x7	# (DW_FORM_data8)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x1	# (DW_AT_sibling)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0x5	# (abbrev code)
+	.uleb128 0x4109	# (TAG: DW_TAG_GNU_call_site)
+	.byte	0	# DW_children_no
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x2115	# (DW_AT_GNU_tail_call)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x31	# (DW_AT_abstract_origin)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0x6	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x7	# (DW_FORM_data8)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x1	# (DW_AT_sibling)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0x7	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x3f	# (DW_AT_external)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x27	# (DW_AT_prototyped)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x7	# (DW_FORM_data8)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.byte	0
+	.byte	0
+	.uleb128 0x8	# (abbrev code)
+	.uleb128 0x34	# (TAG: DW_TAG_variable)
+	.byte	0	# DW_children_no
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x2	# (DW_AT_location)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.byte	0
+	.byte	0
+	.uleb128 0x9	# (abbrev code)
+	.uleb128 0x4109	# (TAG: DW_TAG_GNU_call_site)
+	.byte	0	# DW_children_no
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x31	# (DW_AT_abstract_origin)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_loc,"",@progbits
+.Ldebug_loc0:
+.LLST0:
+	.quad	.LVL3	# Location list begin address (*.LLST0)
+	.quad	.LVL4	# Location list end address (*.LLST0)
+	.value	0x3	# Location expression size
+	.byte	0x70	# DW_OP_breg0
+	.sleb128 1
+	.byte	0x9f	# DW_OP_stack_value
+	.quad	.LVL4	# Location list begin address (*.LLST0)
+	.quad	.LFE4	# Location list end address (*.LLST0)
+	.value	0x1	# Location expression size
+	.byte	0x50	# DW_OP_reg0
+	.quad	0	# Location list terminator begin (*.LLST0)
+	.quad	0	# Location list terminator end (*.LLST0)
+	.section	.debug_aranges,"",@progbits
+	.long	0x3c	# Length of Address Ranges Info
+	.value	0x2	# DWARF Version
+	.long	.Ldebug_info0	# Offset of Compilation Unit Info
+	.byte	0x8	# Size of Address
+	.byte	0	# Size of Segment Descriptor
+	.value	0	# Pad to 16 byte boundary
+	.value	0
+	.quad	.Ltext0	# Address
+	.quad	.Letext0-.Ltext0	# Length
+	.quad	.LFB4	# Address
+	.quad	.LFE4-.LFB4	# Length
+	.quad	0
+	.quad	0
+	.section	.debug_ranges,"",@progbits
+.Ldebug_ranges0:
+	.quad	.Ltext0	# Offset 0
+	.quad	.Letext0
+	.quad	.LFB4	# Offset 0x10
+	.quad	.LFE4
+	.quad	0
+	.quad	0
+	.section	.debug_line,"",@progbits
+.Ldebug_line0:
+	.section	.debug_str,"MS",@progbits,1
+.LASF4:
+	.string	"bar_1"
+.LASF2:
+	.string	"tailcall-only.c"
+.LASF1:
+	.string	"GNU C 4.8.3 20140911 (Red Hat 4.8.3-9) -mtune=generic -march=x86-64 -g -O2"
+.LASF6:
+	.string	"answer"
+.LASF5:
+	.string	"main"
+.LASF3:
+	.string	""
+.LASF0:
+	.string	"foo_1"
+	.ident	"GCC: (GNU) 4.8.3 20140911 (Red Hat 4.8.3-9)"
+	.section	.note.GNU-stack,"",@progbits