Re: [reverse/record] adjust_pc_after_break in reverse execution mode?

Pedro Alves
2008-10-23T23:55:36Z

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> I've done so a bit this morning, and came to a similar
> conclusion, although I noticed Hui's change to set stop_pc in
> TARGET_WAITKIND_NO_HISTORY, also also required. I was wanting
> to find time to play a little bit more, but since you're on to it...

BTW, I noticed that, while reviewing Hui's latest patch
(which was missing setting the waitkind to TARGET_WAITKIND_STOPPED,
hence could never work :-) ). While doing so, I dejagnufied the
nop testcase into the attached. Maybe you'll find it useful.

--
Pedro Alves

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2008-10-24 Pedro Alves <pedro@codesourcery.com>

* gdb.base/decr-pc-rev.c, gdb.base/decr-pc-rev.exp: New test.

---
gdb/testsuite/gdb.base/decr-pc-rev.c | 26 +++++++++
gdb/testsuite/gdb.base/decr-pc-rev.exp | 86 +++++++++++++++++++++++++++++++++
2 files changed, 112 insertions(+)

Index: src/gdb/testsuite/gdb.base/decr-pc-rev.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ src/gdb/testsuite/gdb.base/decr-pc-rev.c 2008-10-23 15:21:02.000000000 +0100
@@ -0,0 +1,26 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2008 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/>. */
+
+int
+main ()
+{
+ asm ("nop"); /* first insn */
+ asm ("nop"); /* second insn */
+ asm ("nop"); /* third insn */
+ asm ("nop"); /* fourth insn */
+ return 0;
+}
Index: src/gdb/testsuite/gdb.base/decr-pc-rev.exp
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ src/gdb/testsuite/gdb.base/decr-pc-rev.exp 2008-10-23 15:21:02.000000000 +0100
@@ -0,0 +1,86 @@
+# Copyright 2008 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/>.
+
+if $tracelevel then {
+ strace $tracelevel
+}
+
+# Test PC adjustment behaviour on decr_pc_after_break archs in reverse
+# and replay modes, in the presence of breakpoints at consecutive
+# instruction addresses.
+
+set testfile "decr-pc-rev"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug nowarnings}] != "" } {
+ untested consecutive.exp
+ return -1
+}
+
+if [get_compiler_info ${binfile}] {
+ return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+if [target_info exists gdb_stub] {
+ gdb_step_for_stub;
+}
+
+if ![runto_main] then {
+ perror "couldn't run to breakpoint"
+ continue
+}
+
+# These breakpoint should be placed at consecutive instructions, such
+# that the address difference between them is equal to
+# decr_pc_after_break on this arquitecture.
+
+set bp_location1 [gdb_get_line_number "first insn"]
+set bp_location2 [gdb_get_line_number "second insn"]
+
+# Enable recording.
+
+gdb_test "record" "" "enable record target"
+
+# Step through the breakpoints creating some history.
+
+gdb_test "next" ".*second insn.*" "next (1)"
+gdb_test "next" ".*third insn.*" "next (2)"
+gdb_test "next" ".*fourth insn.*" "next (3)"
+gdb_test "next" ".*return 0.*" "next (4)"
+
+# Set consecutive breakpoints.
+
+gdb_test "break $bp_location1" \
+ ".*Breakpoint .*$srcfile, line $bp_location1\\." \
+ "first breakpoint line number"
+
+gdb_test "break $bp_location2" \
+ "Breakpoint.*at.* file .*$srcfile, line $bp_location2\\." \
+ "second breakpoint line number"
+
+# Test that reverse-continue doesn't mess with decr_pc_after_break
+
+gdb_test "rc" ".*second insn.*" "reverse continue to breakpoint"
+gdb_test "rn" ".*first insn.*" "reverse next to begining of times"
+
+# Test that replay behaves as normal play.
+gdb_test "next" ".*second insn.*" "next (1) in replay"
+gdb_test "next" ".*third insn.*" "next (2) in replay"