Re: [patch] Fix hw watchpoints regression on i386/x86_64/ia64

Jan Kratochvil
2008-12-21T15:12:01Z

On Wed, 17 Dec 2008 21:12:13 +0100, Ulrich Weigand wrote:
> > + /* Hack around 'unused var' error for some targets here. */
> > + (void) i;
>
> Is this really necessary? The other callers of
> TARGET_CAN_USE_HARDWARE_WATCHPOINT don't do that either ...

It was a copy-paste from existing do_enable_breakpoint() (line 7799).
But it got now removed according to your advice as:
(1) The original code uses `i' and `mem_cnt' initialization in the declaration
while my code initializes them explicitely which suppresses the `unused
variable' GCC warning on gcc-4.3.
(2) GDB already uses explicit `-Wno-unused' by default and it already has
unused variables scattered around which is a scope of different patches.

> > +if {![istarget "i?86-*-*"] && ![istarget "x86_64-*-*"] && ![istarget "ia64-*-*"]
> > + && ![istarget "s390*-*-*"]} then {
> > + verbose "Skipping watchpoint-hw test."
> > + return
> > +}
>
> This test case should respect [target_info exists gdb,no_hardware_watchpoints].
^<-also
as according to my test on ppc64 RHEL-4 gdb-6.3+kernel (both not supporting
ppc hw watchpoints) dejagnu-1.4.4 did not have `no_hardware_watchpoints' set.

Committed: http://sourceware.org/ml/gdb-cvs/2008-12/msg00098.html

Thanks,
Jan

gdb/
2008-12-21 Jan Kratochvil <jan.kratochvil@redhat.com>

Fix hw watchpoints created before the inferior was started.
* breakpoint.c (update_watchpoint): Convert the bp_watchpoint and
bp_hardware_watchpoint types according to the current runtime state.

gdb/testsuite/
2008-12-21 Jan Kratochvil <jan.kratochvil@redhat.com>

* gdb.base/watchpoint-hw.exp, gdb.base/watchpoint-hw.c: New.

--- src/gdb/breakpoint.c 2008/12/08 13:27:38 1.365
+++ src/gdb/breakpoint.c 2008/12/21 15:01:31 1.366
@@ -891,6 +891,27 @@
b->val_valid = 1;
}

+ /* Change the type of breakpoint between hardware assisted or an
+ ordinary watchpoint depending on the hardware support and free
+ hardware slots. REPARSE is set when the inferior is started. */
+ if ((b->type == bp_watchpoint || b->type == bp_hardware_watchpoint)
+ && reparse)
+ {
+ int i, mem_cnt, target_resources_ok, other_type_used;
+
+ i = hw_watchpoint_used_count (bp_hardware_watchpoint,
+ &other_type_used);
+ mem_cnt = can_use_hardware_watchpoint (val_chain);
+
+ if (mem_cnt)
+ target_resources_ok = TARGET_CAN_USE_HARDWARE_WATCHPOINT
+ (bp_hardware_watchpoint, i + mem_cnt, other_type_used);
+ if (!mem_cnt || target_resources_ok <= 0)
+ b->type = bp_watchpoint;
+ else
+ b->type = bp_hardware_watchpoint;
+ }
+
/* Look at each value on the value chain. */
for (v = val_chain; v; v = next)
{
--- src/gdb/testsuite/gdb.base/watchpoint-hw.c
+++ src/gdb/testsuite/gdb.base/watchpoint-hw.c 2008-12-21 15:02:14.633223000 +0000
@@ -0,0 +1,27 @@
+/* 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/>.
+
+ Please email any bugs, comments, and/or additions to this file to:
+ bug-gdb@prep.ai.mit.edu */
+
+int watchee;
+
+int
+main (void)
+{
+ return 0;
+}
--- src/gdb/testsuite/gdb.base/watchpoint-hw.exp
+++ src/gdb/testsuite/gdb.base/watchpoint-hw.exp 2008-12-21 15:02:15.747687000 +0000
@@ -0,0 +1,52 @@
+# 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/>.
+
+# Arch not supporting hw watchpoints does not imply no_hardware_watchpoints set.
+if {(![istarget "i?86-*-*"] && ![istarget "x86_64-*-*"]
+ && ![istarget "ia64-*-*"] && ![istarget "s390*-*-*"])
+ || [target_info exists gdb,no_hardware_watchpoints]} then {
+ verbose "Skipping watchpoint-hw test."
+ return
+}
+
+set testfile watchpoint-hw
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+ untested "Couldn't compile test program"
+ return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# Create the watchpoint before the inferior gets started. Now the native CPU
+# target is still not active and its `to_can_use_hw_breakpoint' is not
+# installed, therefore only a software watchpoint gets created.
+
+gdb_test "watch watchee" "atchpoint 1: watchee"
+
+# `runto_main' or `runto main' would delete the watchpoint created above.
+
+if { [gdb_start_cmd] < 0 } {
+ untested start
+ return -1
+}
+gdb_test "" "main .* at .*" "start"
+
+# Check it is really a `hw'-watchpoint.
+gdb_test "info watchpoints" "1 *hw watchpoint .* watchee"