btrace, frame: fix crash in get_frame_type
authorMarkus Metzger <markus.t.metzger@intel.com>
Tue, 26 Jan 2016 13:58:44 +0000 (14:58 +0100)
committerMarkus Metzger <markus.t.metzger@intel.com>
Fri, 12 Feb 2016 08:49:48 +0000 (09:49 +0100)
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
gdb/frame.c
gdb/frame.h
gdb/infcmd.c
gdb/testsuite/ChangeLog
gdb/testsuite/gdb.btrace/i686-tailcall-only.S [new file with mode: 0644]
gdb/testsuite/gdb.btrace/tailcall-only.c [new file with mode: 0644]
gdb/testsuite/gdb.btrace/tailcall-only.exp [new file with mode: 0644]
gdb/testsuite/gdb.btrace/x86_64-tailcall-only.S [new file with mode: 0644]

index ef88180..e06fc3c 100644 (file)
@@ -1,5 +1,18 @@
 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.
 
 2016-02-12  Markus Metzger  <markus.t.metzger@intel.com>
index b7832c7..d621dd7 100644 (file)
@@ -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
-     are made up by GDB, there must be a real frame in the chain
-     below.  */
+     sets a backtrace limit).
+
+     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.  */
index 7e8b01e..8ee64f1 100644 (file)
@@ -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);
 
index 930dc61..a80bf0a 100644 (file)
@@ -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);
+    }
 }
 \f
 
index 0d61440..63d47cd 100644 (file)
@@ -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.
diff --git a/gdb/testsuite/gdb.btrace/i686-tailcall-only.S b/gdb/testsuite/gdb.btrace/i686-tailcall-only.S
new file mode 100644 (file)
index 0000000..a89f2f2
--- /dev/null
@@ -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
diff --git a/gdb/testsuite/gdb.btrace/tailcall-only.c b/gdb/testsuite/gdb.btrace/tailcall-only.c
new file mode 100644 (file)
index 0000000..5913ddc
--- /dev/null
@@ -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;
+}
diff --git a/gdb/testsuite/gdb.btrace/tailcall-only.exp b/gdb/testsuite/gdb.btrace/tailcall-only.exp
new file mode 100644 (file)
index 0000000..44501f5
--- /dev/null
@@ -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" ".*"
diff --git a/gdb/testsuite/gdb.btrace/x86_64-tailcall-only.S b/gdb/testsuite/gdb.btrace/x86_64-tailcall-only.S
new file mode 100644 (file)
index 0000000..710288a
--- /dev/null
@@ -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