[patch/rfc] Check that "info frame" doesn't change

[Andrew Cagney <cagney at gnu dot org>]

Hello,

(Someone somewhere pointed this out to me, I'm sure others have noticed 
it, but no one's done anything about this, sigh!)

One consequence of the frame rewrite was to modify the behavior of "info 
frame".  Previously it would print the location of registers saved by 
_this_ frame:

 Saved registers:
  rbp at 0x7fbffff2e0, rip at 0x7fbffff2e8

but with the more agressive recursion it started printing out the 
ultimate location of all the previous frame's registers,:

 Saved registers:
  rax at 0x7fbffff120, rbx at 0x7fbffff110, rcx at 0x7fbffff128, rdx at 
0x7fbffff118, rsi at 0x7fbffff100, rdi at 0x7fbffff0f8, rbp at 
0x7fbffff2e0, r8 at 0x7fbffff0b8, r9 at 0x7fbffff0c0, r10 at 
0x7fbffff0c8, r11 at 0x7fbffff0d0, r12 at 0x7fbffff0d8, r13 at 
0x7fbffff0e0, r14 at 0x7fbffff0e8, r15 at 0x7fbffff0f0, rip at 
0x7fbffff2e8, eflags at 0x7fbffff140

Here all the extra saved registers come from a signal handler two levels 
inner to the selected frame.

Further, as the stack evolved, the list of saved registers (and info 
frame output) would change (different more inner frames saved registers 
in different locations).

The attached checks that "info frame" doesn't change as the stack 
evolves.  Tested on fc3/amd64 it currently fails:

FAIL: gdb.base/savedregs.exp: Check main info frame; stack contains 
catcher sigtramp thrower main
FAIL: gdb.base/savedregs.exp: Check main info frame; stack contains 
caller dummy catcher sigtramp thrower main
FAIL: gdb.base/savedregs.exp: Check main info frame; stack contains 
callee caller dummy catcher sigtramp thrower main

If the patch I'm about to post is applied, the test passes on fc3/amd64.

MichaelC, any comments?

Andrew
Index: testsuite/ChangeLog
2004-10-29  Andrew Cagney  <cagney@gnu.org>

	* gdb.base/savedregs.exp, gdb.base/savedregs.c: New files.

Index: testsuite/gdb.base/savedregs.c
===================================================================
RCS file: testsuite/gdb.base/savedregs.c
diff -N testsuite/gdb.base/savedregs.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/savedregs.c	29 Oct 2004 13:33:06 -0000
@@ -0,0 +1,56 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2004 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 2 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, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <sys/time.h>
+
+static volatile int done;
+
+extern int
+callee (int param)
+{
+  return param * done + 1;
+}
+
+extern int
+caller (int a1, int a2, int a3, int a4, int a5, int a6, int a7, int a8)
+{
+  return callee (a1 << a2 * a3 / a4 + a6 & a6 % a7 - a8) + done;
+}
+
+static void
+catcher (int sig)
+{
+  done = 1;
+} /* handler */
+
+static void
+thrower (void)
+{
+  *(char *)0 = 0;
+}
+
+main ()
+{
+  signal (SIGSEGV, catcher);
+  thrower ();
+}
Index: testsuite/gdb.base/savedregs.exp
===================================================================
RCS file: testsuite/gdb.base/savedregs.exp
diff -N testsuite/gdb.base/savedregs.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/savedregs.exp	29 Oct 2004 13:33:06 -0000
@@ -0,0 +1,160 @@
+# Copyright 2004 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 2 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, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
+
+# This test is to check that a frame's "info frame", especially the
+# saved registers list, doesn't change while that frame isn't current.
+
+# It uses the program savedregs.c to construct a somewhat warped
+# backtrace (contains both signal and dummy frames) and then, at each
+# step checks that non-inner frames have consistent "info frame"
+# output.  Note that a frame's "info frame" can only be captured after
+# it is non-current (made a call, interrupted, ...), this is because
+# instructions executed to perform the call may affect "info frame"
+# output.
+
+if [target_info exists gdb,nosignals] {
+    verbose "Skipping savedregs.exp because of nosignals."
+    continue
+}
+
+if $tracelevel then {
+    strace $tracelevel
+}
+
+set prms_id 0
+set bug_id 0
+
+set testfile savedregs
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    untested "Couldn't compile ${module}.c"
+    return -1
+}
+
+# get things started
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# Advance to main
+if { ![runto_main] } {
+    gdb_suppress_tests;
+}
+
+proc process_saved_regs { current inner outer } {
+    global gdb_prompt
+    global expect_out
+    global saved_regs
+
+    # Skip the CURRENT frame.
+
+    set level 1
+
+    # Run over the list of INNER frames capturing the "info frame"
+    # output for each.  Both dummy and sigtramp frames need to be
+    # handled specially: they do not yet have correct function names;
+    # and for dummy frames won't have saved registers.  If there's a
+    # problem, fail but capture the output anyway, hopefully later
+    # "info frame" requests for that same frame will at least fail in
+    # a consistent manner (stops propogated fails).
+
+    foreach func $inner {
+	set saved_regs($func) "error"
+	set test "Get $func info frame"
+	# Both dummy and sigtramp frames have problems.
+	switch $func {
+	    dummy {
+		# Dummy frame's do not have saved registers, and do
+		# not print <dummy>.
+		set pat "Stack frame at .* in .*"
+	    }
+	    sigtramp {
+		# Sigtramp frames don't yet print <signal trampoline>.
+		set pat "Stack frame at .* in .* .* Saved registers:.*"
+	    }
+	    default {
+		set pat "Stack frame at .* in $func .* Saved registers:.*"
+	    }
+	}
+	# If the "info frame" barf, capture the output anyway so that
+	# it does not cascade further failures.
+	gdb_test_multiple "info frame $level" "$test" {
+	    -re "($pat)$gdb_prompt " {
+		set saved_regs($func) "$expect_out(1,string)"
+		pass "$test"
+	    }
+	    -re "(Stack frame at .*)$gdb_prompt " {
+		set saved_regs($func) "$expect_out(1,string)"
+		fail "$test"
+	    }
+	    -re "(Cannot access .*)$gdb_prompt " {
+		set saved_regs($func) "$expect_out(1,string)"
+		fail "$test"
+	    }
+	}
+	incr level
+    }
+    
+    # Now iterate through the list of OUTER frames checking that the
+    # "info frame" output from each still matches what was captured
+    # during an early query.  To avoid cascading failures, checking is
+    # abandoned after the first failure.  The assumption is that,
+    # since frames outer to the botched frame rely on the botched
+    # frame's info, those more outer frames are also botched.  Besides
+    # we've got the failure we're after.
+
+    set ok 1
+    foreach func $outer {
+	set test [concat "Check $func info frame; stack contains" \
+		      $current $inner $outer]
+	if $ok {
+	    set ok 0
+	    set pat [string_to_regexp "$saved_regs($func)"]
+	    gdb_test_multiple "info frame $level" "$test" {
+		-re "$pat$gdb_prompt " {
+		    pass "$test"
+		    set ok 1
+		}
+	    }
+	} {
+	    pass "$test (skipped)"
+	}
+	incr level
+    }
+}
+
+
+# Continue to the signal thrower, capture main's saved-reg info.
+gdb_test "advance thrower" "thrower .* at .*"
+process_saved_regs thrower { main } { }
+
+# Continue to the signal catcher, check main's saved-reg info, capture
+# catcher's saved-reg info.
+gdb_test "handle SIGSEGV pass print nostop"
+gdb_test "advance catcher" "catcher .* at .*"
+process_saved_regs catcher { sigtramp thrower } { main }
+
+# Breakpoint at and call the caller function, saved-regs of main and
+# catcher, capture caller's registers.
+gdb_test "break caller"
+gdb_test "call caller (1,2,3,4,5,6,7,8)"
+process_saved_regs caller { dummy catcher } { sigtramp thrower main }
+
+# Run to callee, again check everything.
+gdb_test "advance callee" "callee .* at .*"
+process_saved_regs callee { caller } { dummy catcher sigtramp thrower main }