Revert "Don't let two frames with the same id end up in the frame chain."

This reverts commit be2c48b4d50b992ba83bc51f086e316621a03a14.

4 files changed, 17 insertions, 646 deletions

diff --git a/gdb/frame.c b/gdb/frame.c
index 535a5a6..63f20d5 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1666,7 +1666,6 @@ get_prev_frame_1 (struct frame_info *this_frame)
 {
   struct frame_id this_id;
   struct gdbarch *gdbarch;
-  struct frame_info *prev_frame;
 
   gdb_assert (this_frame != NULL);
   gdbarch = get_frame_arch (this_frame);
@@ -1768,6 +1767,22 @@ get_prev_frame_1 (struct frame_info *this_frame)
 	}
     }
 
+  /* Check that this and the next frame are not identical.  If they
+     are, there is most likely a stack cycle.  As with the inner-than
+     test above, avoid comparing the inner-most and sentinel frames.  */
+  if (this_frame->level > 0
+      && frame_id_eq (this_id, get_frame_id (this_frame->next)))
+    {
+      if (frame_debug)
+	{
+	  fprintf_unfiltered (gdb_stdlog, "-> ");
+	  fprint_frame (gdb_stdlog, NULL);
+	  fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
+	}
+      this_frame->stop_reason = UNWIND_SAME_ID;
+      return NULL;
+    }
+
   /* Check that this and the next frame do not unwind the PC register
      to the same memory location.  If they do, then even though they
      have different frame IDs, the new frame will be bogus; two
@@ -1815,31 +1830,7 @@ get_prev_frame_1 (struct frame_info *this_frame)
 	}
     }
 
-  prev_frame = get_prev_frame_raw (this_frame);
-
-  /* Check that this and the prev frame are not identical.  If they
-     are, there is most likely a stack cycle.  Unlike the tests above,
-     we do this right after creating the prev frame, to avoid ever
-     ending up with two frames with the same id in the frame
-     chain.  */
-  if (prev_frame != NULL
-      && frame_id_eq (get_frame_id (prev_frame),
-		      get_frame_id (this_frame)))
-    {
-      if (frame_debug)
-	{
-	  fprintf_unfiltered (gdb_stdlog, "-> ");
-	  fprint_frame (gdb_stdlog, NULL);
-	  fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
-	}
-      this_frame->stop_reason = UNWIND_SAME_ID;
-      /* Unlink.  */
-      prev_frame->next = NULL;
-      this_frame->prev = NULL;
-      return NULL;
-    }
-
-  return prev_frame;
+  return get_prev_frame_raw (this_frame);
 }
 
 /* Construct a new "struct frame_info" and link it previous to
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.S b/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.S
deleted file mode 100644
index 4c3bd76..0000000
--- a/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.S
+++ /dev/null
@@ -1,540 +0,0 @@
-/*
-   Copyright 2013 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/>.  */
-
-	/* The FDE entry for "stop_frame" in the .debug_frame section has
-	been hand modified to mark a set of registers as DW_CFA_same_value.
-	Otherwise this file is as generated by gcc 4.7.2 for x86_64.  */
-	.file	"dw2-dup-frame.c"
-	.text
-.Ltext0:
-	.globl	stop_frame
-	.type	stop_frame, @function
-stop_frame:
-.LFB0:
-	.file 1 "dw2-dup-frame.c"
-	.loc 1 19 0
-	pushq	%rbp
-.LCFI0:
-	movq	%rsp, %rbp
-.LCFI1:
-	.loc 1 22 0
-	popq	%rbp
-.LCFI2:
-	ret
-.LFE0:
-	.size	stop_frame, .-stop_frame
-	.globl	first_frame
-	.type	first_frame, @function
-first_frame:
-.LFB1:
-	.loc 1 26 0
-	pushq	%rbp
-.LCFI3:
-	movq	%rsp, %rbp
-.LCFI4:
-	.loc 1 27 0
-	movl	$0, %eax
-	call	stop_frame
-	.loc 1 28 0
-	popq	%rbp
-.LCFI5:
-	ret
-.LFE1:
-	.size	first_frame, .-first_frame
-	.globl	main
-	.type	main, @function
-main:
-.LFB2:
-	.loc 1 32 0
-	pushq	%rbp
-.LCFI6:
-	movq	%rsp, %rbp
-.LCFI7:
-	.loc 1 33 0
-	movl	$0, %eax
-	call	first_frame
-	.loc 1 35 0
-	movl	$0, %eax
-	.loc 1 36 0
-	popq	%rbp
-.LCFI8:
-	ret
-.LFE2:
-	.size	main, .-main
-	.section	.debug_frame,"",@progbits
-.Lframe0:
-	.long	.LECIE0-.LSCIE0
-.LSCIE0:
-	.long	0xffffffff
-	.byte	0x1
-	.string	""
-	.uleb128 0x1
-	.sleb128 -8
-	.byte	0x10
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.byte	0x90
-	.uleb128 0x1
-	.align 8
-.LECIE0:
-	/* This FDE entry, for stop_frame was modified to mark
-	   registers 0 -> 16 (rax..ra/rip) as being DW_CFA_same_value.  */
-.LSFDE0:
-	.long	.LEFDE0-.LASFDE0
-.LASFDE0:
-	.long	.Lframe0
-	.quad	.LFB0
-	.quad	.LFE0-.LFB0
-
-		/* START OF NEW CONTENT.  */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x0			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x1			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x2			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x3			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x4			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x5			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x6			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x7			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x8			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x9			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0xa			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0xb			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0xc			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0xd			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0xe			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0xf			/*   ULEB128 register */
-	.byte	0x8			/* DW_CFA_same_value */
-	.uleb128 0x10			 /*   ULEB128 register */
-		/* END OF NEW CONTENT.  */
-
-	.byte	0x4
-	.long	.LCFI0-.LFB0
-	.byte	0xe
-	.uleb128 0x10
-	.byte	0x86
-	.uleb128 0x2
-	.byte	0x4
-	.long	.LCFI1-.LCFI0
-	.byte	0xd
-	.uleb128 0x6
-	.byte	0x4
-	.long	.LCFI2-.LCFI1
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.align 8
-.LEFDE0:
-.LSFDE2:
-	.long	.LEFDE2-.LASFDE2
-.LASFDE2:
-	.long	.Lframe0
-	.quad	.LFB1
-	.quad	.LFE1-.LFB1
-	.byte	0x4
-	.long	.LCFI3-.LFB1
-	.byte	0xe
-	.uleb128 0x10
-	.byte	0x86
-	.uleb128 0x2
-	.byte	0x4
-	.long	.LCFI4-.LCFI3
-	.byte	0xd
-	.uleb128 0x6
-	.byte	0x4
-	.long	.LCFI5-.LCFI4
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.align 8
-.LEFDE2:
-.LSFDE4:
-	.long	.LEFDE4-.LASFDE4
-.LASFDE4:
-	.long	.Lframe0
-	.quad	.LFB2
-	.quad	.LFE2-.LFB2
-	.byte	0x4
-	.long	.LCFI6-.LFB2
-	.byte	0xe
-	.uleb128 0x10
-	.byte	0x86
-	.uleb128 0x2
-	.byte	0x4
-	.long	.LCFI7-.LCFI6
-	.byte	0xd
-	.uleb128 0x6
-	.byte	0x4
-	.long	.LCFI8-.LCFI7
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.align 8
-.LEFDE4:
-	.section	.eh_frame,"a",@progbits
-.Lframe1:
-	.long	.LECIE1-.LSCIE1
-.LSCIE1:
-	.long	0
-	.byte	0x1
-	.string	"zR"
-	.uleb128 0x1
-	.sleb128 -8
-	.byte	0x10
-	.uleb128 0x1
-	.byte	0x3
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.byte	0x90
-	.uleb128 0x1
-	.align 8
-.LECIE1:
-.LSFDE7:
-	.long	.LEFDE7-.LASFDE7
-.LASFDE7:
-	.long	.LASFDE7-.Lframe1
-	.long	.LFB0
-	.long	.LFE0-.LFB0
-	.uleb128 0
-	.byte	0x4
-	.long	.LCFI0-.LFB0
-	.byte	0xe
-	.uleb128 0x10
-	.byte	0x86
-	.uleb128 0x2
-	.byte	0x4
-	.long	.LCFI1-.LCFI0
-	.byte	0xd
-	.uleb128 0x6
-	.byte	0x4
-	.long	.LCFI2-.LCFI1
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.align 8
-.LEFDE7:
-.LSFDE9:
-	.long	.LEFDE9-.LASFDE9
-.LASFDE9:
-	.long	.LASFDE9-.Lframe1
-	.long	.LFB1
-	.long	.LFE1-.LFB1
-	.uleb128 0
-	.byte	0x4
-	.long	.LCFI3-.LFB1
-	.byte	0xe
-	.uleb128 0x10
-	.byte	0x86
-	.uleb128 0x2
-	.byte	0x4
-	.long	.LCFI4-.LCFI3
-	.byte	0xd
-	.uleb128 0x6
-	.byte	0x4
-	.long	.LCFI5-.LCFI4
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.align 8
-.LEFDE9:
-.LSFDE11:
-	.long	.LEFDE11-.LASFDE11
-.LASFDE11:
-	.long	.LASFDE11-.Lframe1
-	.long	.LFB2
-	.long	.LFE2-.LFB2
-	.uleb128 0
-	.byte	0x4
-	.long	.LCFI6-.LFB2
-	.byte	0xe
-	.uleb128 0x10
-	.byte	0x86
-	.uleb128 0x2
-	.byte	0x4
-	.long	.LCFI7-.LCFI6
-	.byte	0xd
-	.uleb128 0x6
-	.byte	0x4
-	.long	.LCFI8-.LCFI7
-	.byte	0xc
-	.uleb128 0x7
-	.uleb128 0x8
-	.align 8
-.LEFDE11:
-	.text
-.Letext0:
-	.section	.debug_info,"",@progbits
-.Ldebug_info0:
-	.long	0x8c
-	.value	0x2
-	.long	.Ldebug_abbrev0
-	.byte	0x8
-	.uleb128 0x1
-	.long	.LASF2
-	.byte	0x1
-	.long	.LASF3
-	.long	.LASF4
-	.quad	.Ltext0
-	.quad	.Letext0
-	.long	.Ldebug_line0
-	.uleb128 0x2
-	.byte	0x1
-	.long	.LASF0
-	.byte	0x1
-	.byte	0x12
-	.quad	.LFB0
-	.quad	.LFE0
-	.long	.LLST0
-	.byte	0x1
-	.uleb128 0x3
-	.byte	0x1
-	.long	.LASF1
-	.byte	0x1
-	.byte	0x19
-	.quad	.LFB1
-	.quad	.LFE1
-	.long	.LLST1
-	.byte	0x1
-	.uleb128 0x4
-	.byte	0x1
-	.long	.LASF5
-	.byte	0x1
-	.byte	0x1f
-	.long	0x88
-	.quad	.LFB2
-	.quad	.LFE2
-	.long	.LLST2
-	.byte	0x1
-	.uleb128 0x5
-	.byte	0x4
-	.byte	0x5
-	.string	"int"
-	.byte	0
-	.section	.debug_abbrev,"",@progbits
-.Ldebug_abbrev0:
-	.uleb128 0x1
-	.uleb128 0x11
-	.byte	0x1
-	.uleb128 0x25
-	.uleb128 0xe
-	.uleb128 0x13
-	.uleb128 0xb
-	.uleb128 0x3
-	.uleb128 0xe
-	.uleb128 0x1b
-	.uleb128 0xe
-	.uleb128 0x11
-	.uleb128 0x1
-	.uleb128 0x12
-	.uleb128 0x1
-	.uleb128 0x10
-	.uleb128 0x6
-	.byte	0
-	.byte	0
-	.uleb128 0x2
-	.uleb128 0x2e
-	.byte	0
-	.uleb128 0x3f
-	.uleb128 0xc
-	.uleb128 0x3
-	.uleb128 0xe
-	.uleb128 0x3a
-	.uleb128 0xb
-	.uleb128 0x3b
-	.uleb128 0xb
-	.uleb128 0x11
-	.uleb128 0x1
-	.uleb128 0x12
-	.uleb128 0x1
-	.uleb128 0x40
-	.uleb128 0x6
-	.uleb128 0x2117
-	.uleb128 0xc
-	.byte	0
-	.byte	0
-	.uleb128 0x3
-	.uleb128 0x2e
-	.byte	0
-	.uleb128 0x3f
-	.uleb128 0xc
-	.uleb128 0x3
-	.uleb128 0xe
-	.uleb128 0x3a
-	.uleb128 0xb
-	.uleb128 0x3b
-	.uleb128 0xb
-	.uleb128 0x11
-	.uleb128 0x1
-	.uleb128 0x12
-	.uleb128 0x1
-	.uleb128 0x40
-	.uleb128 0x6
-	.uleb128 0x2116
-	.uleb128 0xc
-	.byte	0
-	.byte	0
-	.uleb128 0x4
-	.uleb128 0x2e
-	.byte	0
-	.uleb128 0x3f
-	.uleb128 0xc
-	.uleb128 0x3
-	.uleb128 0xe
-	.uleb128 0x3a
-	.uleb128 0xb
-	.uleb128 0x3b
-	.uleb128 0xb
-	.uleb128 0x49
-	.uleb128 0x13
-	.uleb128 0x11
-	.uleb128 0x1
-	.uleb128 0x12
-	.uleb128 0x1
-	.uleb128 0x40
-	.uleb128 0x6
-	.uleb128 0x2116
-	.uleb128 0xc
-	.byte	0
-	.byte	0
-	.uleb128 0x5
-	.uleb128 0x24
-	.byte	0
-	.uleb128 0xb
-	.uleb128 0xb
-	.uleb128 0x3e
-	.uleb128 0xb
-	.uleb128 0x3
-	.uleb128 0x8
-	.byte	0
-	.byte	0
-	.byte	0
-	.section	.debug_loc,"",@progbits
-.Ldebug_loc0:
-.LLST0:
-	.quad	.LFB0-.Ltext0
-	.quad	.LCFI0-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 8
-	.quad	.LCFI0-.Ltext0
-	.quad	.LCFI1-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 16
-	.quad	.LCFI1-.Ltext0
-	.quad	.LCFI2-.Ltext0
-	.value	0x2
-	.byte	0x76
-	.sleb128 16
-	.quad	.LCFI2-.Ltext0
-	.quad	.LFE0-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 8
-	.quad	0
-	.quad	0
-.LLST1:
-	.quad	.LFB1-.Ltext0
-	.quad	.LCFI3-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 8
-	.quad	.LCFI3-.Ltext0
-	.quad	.LCFI4-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 16
-	.quad	.LCFI4-.Ltext0
-	.quad	.LCFI5-.Ltext0
-	.value	0x2
-	.byte	0x76
-	.sleb128 16
-	.quad	.LCFI5-.Ltext0
-	.quad	.LFE1-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 8
-	.quad	0
-	.quad	0
-.LLST2:
-	.quad	.LFB2-.Ltext0
-	.quad	.LCFI6-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 8
-	.quad	.LCFI6-.Ltext0
-	.quad	.LCFI7-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 16
-	.quad	.LCFI7-.Ltext0
-	.quad	.LCFI8-.Ltext0
-	.value	0x2
-	.byte	0x76
-	.sleb128 16
-	.quad	.LCFI8-.Ltext0
-	.quad	.LFE2-.Ltext0
-	.value	0x2
-	.byte	0x77
-	.sleb128 8
-	.quad	0
-	.quad	0
-	.section	.debug_aranges,"",@progbits
-	.long	0x2c
-	.value	0x2
-	.long	.Ldebug_info0
-	.byte	0x8
-	.byte	0
-	.value	0
-	.value	0
-	.quad	.Ltext0
-	.quad	.Letext0-.Ltext0
-	.quad	0
-	.quad	0
-	.section	.debug_line,"",@progbits
-.Ldebug_line0:
-	.section	.debug_str,"MS",@progbits,1
-.LASF0:
-	.string	"stop_frame"
-.LASF3:
-	.string	"dw2-reg-undefined.c"
-.LASF2:
-	.string	"GNU C 4.7.2"
-.LASF1:
-	.string	"first_frame"
-.LASF5:
-	.string	"main"
-.LASF4:
-	.string	"/home/username/src/gdb/testsuite/gdb.dwarf2"
-	.ident	"GCC: (GNU) 4.7.2"
-	.section	.note.GNU-stack,"",@progbits
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.c b/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.c
deleted file mode 100644
index 4868d05..0000000
--- a/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.c
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
-   Copyright 2013 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/>.  */
-
-void
-stop_frame ()
-{
-  /* The debug information for this frame is modified in the accompanying
-     .S file, to mark a set of registers as being DW_CFA_same_value.  */
-}
-
-void
-first_frame ()
-{
-  stop_frame ();
-}
-
-int
-main ()
-{
-  first_frame ();
-
-  return 0;
-}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.exp b/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.exp
deleted file mode 100644
index a57ab8a..0000000
--- a/gdb/testsuite/gdb.dwarf2/dw2-dup-frame.exp
+++ /dev/null
@@ -1,44 +0,0 @@
-# Copyright 2013 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/>.
-load_lib dwarf.exp
-
-# This test can only be run on targets which support DWARF-2 and use gas.
-if {![dwarf2_support]} {
-    return 0
-}
-
-# This test can only be run on x86_64 targets.
-if {![istarget "x86_64-*-*"] || ![is_lp64_target]} {
-    return 0
-}
-
-standard_testfile .S
-
-if { [prepare_for_testing $testfile.exp $testfile $srcfile {nodebug}] } {
-    return -1
-}
-
-if ![runto stop_frame] {
-    perror "Failed to stop in stop_frame"
-    return -1
-}
-
-gdb_test "bt" \
-    "#0  stop_frame \[^\r\n\]*\r\nBacktrace stopped: previous frame identical to this frame \\(corrupt stack\\?\\)" \
-    "backtrace from stop_frame"
-
-gdb_test "up" \
-    "Initial frame selected; you cannot go up\\\." \
-    "up from stop_frame"