PR symtab/18392

Initially there is some chain (let's say the longest one
but that doe snot matter).  Consequently its elements from the middle are
being removed and there remains only some few unambiguous top and bottom ones.

The original idea why the comparison should be sharp ("<") was that if there
are multiple chains like (0xaddr show jmp instruction address):
        main(0x100) -> a(0x200) -> d(0x400)
        main(0x100) -> a(0x200) -> c(0x300) -> d(0x400)
then - such situation cannot exist - if two jmp instructions in "a" have the
same address they must also jump to the same address (*).

(*) jump to a computed address would be never considered for the DWARF
    tail-call records.

So there could be:
        main(0x100) -> a(0x200) -> d(0x400)
        main(0x100) -> a(0x270) -> c(0x300) -> d(0x400)
But then "a" frame itself is ambiguous and it must not be displayed.

I did not realize that there can be self-tail-call:
        main(0x100) -> a(0x200) -> d(0x400)
        main(0x100) -> a(0x280) -> a(0x200) -> d(0x400)
which intersects to:
        main(0x100) -> <???>? -> a(0x200) -> d(0x400)
And so if the first chain was chosen the
        main(0x100) -> a(0x200) -> d(0x400)
then the final intersection has callers+callees==length.

> for example, if CALLERS is 3 and
> CALLEES is 2, what does the chain look like?

main(0x100) -> x(0x150) -> y(0x200) -> <???>? -> a(0x200) -> d(0x400)

And if LENGTH is 7 then:
        call_site[0] = main(0x100)
        call_site[1] = x(0x150)
        call_site[2] = y(0x200)
        call_site[3] = garbage
        call_site[4] = garbage
        call_site[5] = a(0x200)
        call_site[6] = d(0x400)

gdb/ChangeLog
2015-06-01  Andreas Schwab  <schwab@linux-m68k.org>
	    Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR symtab/18392
	* dwarf2-frame-tailcall.c (pretended_chain_levels): Correct
	assertion.
	* dwarf2loc.c (chain_candidate): Likewise.

gdb/testsuite/ChangeLog
2015-06-01  Jan Kratochvil  <jan.kratochvil@redhat.com>

	PR symtab/18392
	* gdb.arch/amd64-tailcall-self.S: New file.
	* gdb.arch/amd64-tailcall-self.c: New file.
	* gdb.arch/amd64-tailcall-self.exp: New file.

3 files changed, 685 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.arch/amd64-tailcall-self.S b/gdb/testsuite/gdb.arch/amd64-tailcall-self.S
new file mode 100644
index 0000000..b1ca7c8
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-tailcall-self.S
@@ -0,0 +1,614 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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 source file was generated by:
+   gcc -o gdb.arch/amd64-tailcall-self.S -S gdb.arch/amd64-tailcall-self.c -Wall -g -dA -Os
+   */
+
+	.file	"amd64-tailcall-self.c"
+	.text
+.Ltext0:
+	.section	.text.unlikely,"ax",@progbits
+.LCOLDB0:
+	.text
+.LHOTB0:
+	.section	.text.unlikely
+.Ltext_cold0:
+	.text
+	.type	b, @function
+b:
+.LFB0:
+	.file 1 "amd64-tailcall-self.c"
+	# amd64-tailcall-self.c:1
+	.loc 1 1 0
+	.cfi_startproc
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# amd64-tailcall-self.c:2
+	.loc 1 2 0
+# SUCC: EXIT [100.0%] 
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	b, .-b
+	.section	.text.unlikely
+.LCOLDE0:
+	.text
+.LHOTE0:
+	.section	.text.unlikely
+.LCOLDB1:
+	.text
+.LHOTB1:
+	.globl	c
+	.type	c, @function
+c:
+.LFB1:
+	# amd64-tailcall-self.c:7
+	.loc 1 7 0
+	.cfi_startproc
+.LVL0:
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# amd64-tailcall-self.c:8
+	.loc 1 8 0
+	leal	1(%rdi), %eax
+# SUCC: EXIT [100.0%] 
+	# amd64-tailcall-self.c:9
+	.loc 1 9 0
+	ret
+	.cfi_endproc
+.LFE1:
+	.size	c, .-c
+	.section	.text.unlikely
+.LCOLDE1:
+	.text
+.LHOTE1:
+	.section	.text.unlikely
+.LCOLDB2:
+	.text
+.LHOTB2:
+	.globl	a
+	.type	a, @function
+a:
+.LFB2:
+	# amd64-tailcall-self.c:11
+	.loc 1 11 0
+	.cfi_startproc
+.LVL1:
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU) 3 [100.0%]  (DFS_BACK,CAN_FALLTHRU)
+.L5:
+	# amd64-tailcall-self.c:12
+	.loc 1 12 0
+#APP
+# 12 "amd64-tailcall-self.c" 1
+	nop;nop;nop
+# 0 "" 2
+	# amd64-tailcall-self.c:13
+	.loc 1 13 0
+#NO_APP
+	movl	i(%rip), %edi
+	leal	-1(%rdi), %eax
+	cmpl	$9, %eax
+# SUCC: 3 [91.0%]  (FALLTHRU,CAN_FALLTHRU) 4 [9.0%]  (CAN_FALLTHRU,LOOP_EXIT)
+	ja	.L4
+# BLOCK 3 freq:9100 seq:1
+# PRED: 2 [91.0%]  (FALLTHRU,CAN_FALLTHRU)
+	# amd64-tailcall-self.c:14
+	.loc 1 14 0
+	orl	$1, %edi
+	movl	%edi, i(%rip)
+# SUCC: 2 [100.0%]  (DFS_BACK,CAN_FALLTHRU)
+	jmp	.L5
+.Lfirsttailcall:
+# BLOCK 4 freq:900 seq:2
+# PRED: 2 [9.0%]  (CAN_FALLTHRU,LOOP_EXIT)
+.L4:
+	# amd64-tailcall-self.c:16
+	.loc 1 16 0
+	cmpl	$0, %edi
+# SUCC: 5 [19.9%]  (FALLTHRU,CAN_FALLTHRU) 6 [80.1%]  (CAN_FALLTHRU)
+	jne	.L3
+# BLOCK 5 freq:179 seq:3
+# PRED: 4 [19.9%]  (FALLTHRU,CAN_FALLTHRU)
+# SUCC: EXIT [100.0%]  (ABNORMAL,SIBCALL)
+	# amd64-tailcall-self.c:17
+	.loc 1 17 0
+	jmp	b
+.LVL2:
+# BLOCK 6 freq:721 seq:4
+# PRED: 4 [80.1%]  (CAN_FALLTHRU)
+.L3:
+# SUCC: EXIT [100.0%] 
+	ret
+	.cfi_endproc
+.LFE2:
+	.size	a, .-a
+	.section	.text.unlikely
+.LCOLDE2:
+	.text
+.LHOTE2:
+	.section	.text.unlikely
+.LCOLDB3:
+	.section	.text.startup,"ax",@progbits
+.LHOTB3:
+	.globl	main
+	.type	main, @function
+main:
+.LFB3:
+	# amd64-tailcall-self.c:20
+	.loc 1 20 0
+	.cfi_startproc
+.LVL3:
+# BLOCK 2 freq:10000 seq:0
+# PRED: ENTRY [100.0%]  (FALLTHRU)
+	# amd64-tailcall-self.c:21
+	.loc 1 21 0
+	call	a
+.LVL4:
+	# amd64-tailcall-self.c:23
+	.loc 1 23 0
+	xorl	%eax, %eax
+# SUCC: EXIT [100.0%] 
+	ret
+	.cfi_endproc
+.LFE3:
+	.size	main, .-main
+	.section	.text.unlikely
+.LCOLDE3:
+	.section	.text.startup
+.LHOTE3:
+	.comm	i,4,4
+	.text
+.Letext0:
+	.section	.text.unlikely
+.Letext_cold0:
+	.section	.debug_info,"",@progbits
+.Ldebug_info0:
+	.long	2f-1f	# Length of Compilation Unit Info
+1:
+	.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	.LASF4	# DW_AT_producer: "GNU C 4.9.2 20150212 (Red Hat 4.9.2-6) -mtune=generic -march=x86-64 -g -Os"
+	.byte	0x1	# DW_AT_language
+	.long	.LASF5	# DW_AT_name: "amd64-tailcall-self.c"
+	.long	.LASF6	# DW_AT_comp_dir: "/home/jkratoch/t"
+	.long	.Ldebug_ranges0+0	# DW_AT_ranges
+	.quad	0	# DW_AT_low_pc
+	.long	.Ldebug_line0	# DW_AT_stmt_list
+die29:
+	.uleb128 0x2	# (DIE (0x29) DW_TAG_subprogram)
+	.ascii "b\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x1	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.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 (0x40) DW_TAG_subprogram)
+			# DW_AT_external
+	.ascii "c\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x7	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	die6b	# 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
+	.uleb128 0x4	# (DIE (0x5f) DW_TAG_formal_parameter)
+	.ascii "q\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x7	# DW_AT_decl_line
+	.long	die6b	# DW_AT_type
+	.uleb128 0x1	# DW_AT_location
+	.byte	0x55	# DW_OP_reg5
+	.byte	0	# end of children of DIE 0x40
+die6b:
+	.uleb128 0x5	# (DIE (0x6b) DW_TAG_base_type)
+	.byte	0x4	# DW_AT_byte_size
+	.byte	0x5	# DW_AT_encoding
+	.ascii "int\0"	# DW_AT_name
+die72:
+	.uleb128 0x6	# (DIE (0x72) DW_TAG_subprogram)
+			# DW_AT_external
+	.ascii "a\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0xb	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.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
+	.uleb128 0x4	# (DIE (0x8d) DW_TAG_formal_parameter)
+	.ascii "q\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0xb	# DW_AT_decl_line
+	.long	die6b	# DW_AT_type
+	.uleb128 0x4	# DW_AT_location
+	.byte	0xf3	# DW_OP_GNU_entry_value
+	.uleb128 0x1
+	.byte	0x55	# DW_OP_reg5
+	.byte	0x9f	# DW_OP_stack_value
+	.uleb128 0x7	# (DIE () DW_TAG_GNU_call_site)
+	.quad	.Lfirsttailcall	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	die72	# DW_AT_abstract_origin
+	.uleb128 0x7	# (DIE (0x9b) DW_TAG_GNU_call_site)
+	.quad	.LVL2	# DW_AT_low_pc
+			# DW_AT_GNU_tail_call
+	.long	die29	# DW_AT_abstract_origin
+	.byte	0	# end of children of DIE 0x72
+	.uleb128 0x8	# (DIE (0xa9) DW_TAG_subprogram)
+			# DW_AT_external
+	.long	.LASF0	# DW_AT_name: "main"
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x14	# DW_AT_decl_line
+			# DW_AT_prototyped
+	.long	die6b	# 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
+	.uleb128 0x9	# (DIE (0xca) DW_TAG_formal_parameter)
+	.long	.LASF1	# DW_AT_name: "argc"
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x14	# DW_AT_decl_line
+	.long	die6b	# DW_AT_type
+	.long	.LLST0	# DW_AT_location
+	.uleb128 0x9	# (DIE (0xd9) DW_TAG_formal_parameter)
+	.long	.LASF2	# DW_AT_name: "argv"
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x14	# DW_AT_decl_line
+	.long	diefe	# DW_AT_type
+	.long	.LLST1	# DW_AT_location
+	.uleb128 0xa	# (DIE (0xe8) DW_TAG_GNU_call_site)
+	.quad	.LVL4	# DW_AT_low_pc
+	.long	die72	# DW_AT_abstract_origin
+	.uleb128 0xb	# (DIE (0xf5) DW_TAG_GNU_call_site_parameter)
+	.uleb128 0x1	# DW_AT_location
+	.byte	0x55	# DW_OP_reg5
+	.uleb128 0x3	# DW_AT_GNU_call_site_value
+	.byte	0xf3	# DW_OP_GNU_entry_value
+	.uleb128 0x1
+	.byte	0x55	# DW_OP_reg5
+	.byte	0	# end of children of DIE 0xe8
+	.byte	0	# end of children of DIE 0xa9
+diefe:
+	.uleb128 0xc	# (DIE (0xfe) DW_TAG_pointer_type)
+	.byte	0x8	# DW_AT_byte_size
+	.long	die104	# DW_AT_type
+die104:
+	.uleb128 0xc	# (DIE (0x104) DW_TAG_pointer_type)
+	.byte	0x8	# DW_AT_byte_size
+	.long	die10a	# DW_AT_type
+die10a:
+	.uleb128 0xd	# (DIE (0x10a) DW_TAG_base_type)
+	.byte	0x1	# DW_AT_byte_size
+	.byte	0x6	# DW_AT_encoding
+	.long	.LASF3	# DW_AT_name: "char"
+	.uleb128 0xe	# (DIE (0x111) DW_TAG_variable)
+	.ascii "i\0"	# DW_AT_name
+	.byte	0x1	# DW_AT_decl_file (amd64-tailcall-self.c)
+	.byte	0x5	# DW_AT_decl_line
+	.long	die6b	# DW_AT_type
+			# DW_AT_external
+	.uleb128 0x9	# DW_AT_location
+	.byte	0x3	# DW_OP_addr
+	.quad	i
+	.byte	0	# end of children of DIE 0xb
+2:
+	.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 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 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 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 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)
+	.byte	0
+	.byte	0
+	.uleb128 0x4	# (abbrev code)
+	.uleb128 0x5	# (TAG: DW_TAG_formal_parameter)
+	.byte	0	# DW_children_no
+	.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 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x2	# (DW_AT_location)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.byte	0
+	.byte	0
+	.uleb128 0x5	# (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 0x6	# (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 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 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 0x7	# (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 0x8	# (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 0x9	# (abbrev code)
+	.uleb128 0x5	# (TAG: DW_TAG_formal_parameter)
+	.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 0xa	# (abbrev code)
+	.uleb128 0x4109	# (TAG: DW_TAG_GNU_call_site)
+	.byte	0x1	# DW_children_yes
+	.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
+	.uleb128 0xb	# (abbrev code)
+	.uleb128 0x410a	# (TAG: DW_TAG_GNU_call_site_parameter)
+	.byte	0	# DW_children_no
+	.uleb128 0x2	# (DW_AT_location)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2111	# (DW_AT_GNU_call_site_value)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.byte	0
+	.byte	0
+	.uleb128 0xc	# (abbrev code)
+	.uleb128 0xf	# (TAG: DW_TAG_pointer_type)
+	.byte	0	# DW_children_no
+	.uleb128 0xb	# (DW_AT_byte_size)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.byte	0
+	.byte	0
+	.uleb128 0xd	# (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 0xe	# (DW_FORM_strp)
+	.byte	0
+	.byte	0
+	.uleb128 0xe	# (abbrev code)
+	.uleb128 0x34	# (TAG: DW_TAG_variable)
+	.byte	0	# DW_children_no
+	.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 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x3f	# (DW_AT_external)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x2	# (DW_AT_location)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_loc,"",@progbits
+.Ldebug_loc0:
+.LLST0:
+	.quad	.LVL3	# Location list begin address (*.LLST0)
+	.quad	.LVL4-1	# Location list end address (*.LLST0)
+	.value	0x1	# Location expression size
+	.byte	0x55	# DW_OP_reg5
+	.quad	.LVL4-1	# Location list begin address (*.LLST0)
+	.quad	.LFE3	# Location list end address (*.LLST0)
+	.value	0x4	# Location expression size
+	.byte	0xf3	# DW_OP_GNU_entry_value
+	.uleb128 0x1
+	.byte	0x55	# DW_OP_reg5
+	.byte	0x9f	# DW_OP_stack_value
+	.quad	0	# Location list terminator begin (*.LLST0)
+	.quad	0	# Location list terminator end (*.LLST0)
+.LLST1:
+	.quad	.LVL3	# Location list begin address (*.LLST1)
+	.quad	.LVL4-1	# Location list end address (*.LLST1)
+	.value	0x1	# Location expression size
+	.byte	0x54	# DW_OP_reg4
+	.quad	.LVL4-1	# Location list begin address (*.LLST1)
+	.quad	.LFE3	# Location list end address (*.LLST1)
+	.value	0x4	# Location expression size
+	.byte	0xf3	# DW_OP_GNU_entry_value
+	.uleb128 0x1
+	.byte	0x54	# DW_OP_reg4
+	.byte	0x9f	# DW_OP_stack_value
+	.quad	0	# Location list terminator begin (*.LLST1)
+	.quad	0	# Location list terminator end (*.LLST1)
+	.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	.LFB3	# Address
+	.quad	.LFE3-.LFB3	# Length
+	.quad	0
+	.quad	0
+	.section	.debug_ranges,"",@progbits
+.Ldebug_ranges0:
+	.quad	.Ltext0	# Offset 0
+	.quad	.Letext0
+	.quad	.LFB3	# Offset 0x10
+	.quad	.LFE3
+	.quad	0
+	.quad	0
+	.section	.debug_line,"",@progbits
+.Ldebug_line0:
+	.section	.debug_str,"MS",@progbits,1
+.LASF1:
+	.string	"argc"
+.LASF0:
+	.string	"main"
+.LASF4:
+	.string	"GNU C 4.9.2 20150212 (Red Hat 4.9.2-6) -mtune=generic -march=x86-64 -g -Os"
+.LASF5:
+	.string	"amd64-tailcall-self.c"
+.LASF6:
+	.string	""
+.LASF3:
+	.string	"char"
+.LASF2:
+	.string	"argv"
+	.ident	"GCC: (GNU) 4.9.2 20150212 (Red Hat 4.9.2-6)"
diff --git a/gdb/testsuite/gdb.arch/amd64-tailcall-self.c b/gdb/testsuite/gdb.arch/amd64-tailcall-self.c
new file mode 100644
index 0000000..0b40dcb
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-tailcall-self.c
@@ -0,0 +1,40 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 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/>.  */
+
+__attribute__((noinline,noclone)) static void b(void) {
+  asm volatile("");
+}
+
+int i;
+
+__attribute__((noinline,noclone)) int c(int q) {
+  return q+1;
+}
+
+__attribute__((noinline,noclone)) void a(int q) {
+  asm volatile("nop;nop;nop"::"g"(q):"memory");
+  if (i>=1&&i<=10) {
+    i|=1;
+    a(i);
+  } else if (i==0)
+    b();
+}
+
+int main(int argc,char **argv) {
+  a(argc);
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/amd64-tailcall-self.exp b/gdb/testsuite/gdb.arch/amd64-tailcall-self.exp
new file mode 100644
index 0000000..0803ff2
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/amd64-tailcall-self.exp
@@ -0,0 +1,31 @@
+# Copyright (C) 2015 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/>.
+
+standard_testfile .S
+
+if { ![istarget x86_64-*-* ] || ![is_lp64_target] } {
+    verbose "Skipping ${testfile}."
+    return
+}
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile} {}] } {
+    return -1
+}
+
+if ![runto b] {
+    return -1
+}
+
+gdb_test "bt" "#0 +b \\(\\) at \[^\r\n\]*\r\n#1 +0x\[0-9a-f\]+ in a \\(q=<optimized out>\\) at \[^\r\n\]*\r\n#2 +0x\[0-9a-f\]+ in main \\(\[^\r\n\]*\\) at .*"