[PATCH] PowerPC, fix gdb.base/watchpoint.exp on Power 9

[PATCH] PowerPC, fix gdb.base/watchpoint.exp on Power 9

[Carl Love]

GDB maintainers:

The gdb.base/watchpoint.exp test uses the check [target_info exists
gdb,no_hardware_watchpoints] to determine if the processor supports
hardware watchpoints or not.  The various PowerPC processors support
hardware watchpoints except on Power 9 where they are disabled.  The
test skip_hw_watchpoint_tests must be used to correctly determine if
the PowerPC processor supports hardware watchpoints or not.

This patch updates the test to determine if the processor supports
hardware breakpoints or not.  

The patch has been tested on X86-64 with no regressions.  The patch was
tested on Power 9 to ensure the test only runs without hardware
watchpoints enabled.  On Power 8 and 10, the test runs but still
reports errors due to an internal GDB issue that is not properly
checking the resource availability.  This issue will be addressed in a
future patch.

Please let me know if this patch is acceptable for GDB mainline. 
Thanks.

                           Carl Love

-----------------------------------------
PowerPC, fix gdb.base/watchpoint.exp on Power 9

Test gdb.base/watchpoint.exp generates 4 test errors on Power 9.  The
test uses the test [target_info exists gdb,no_hardware_watchpoints] to
determine if the processor supports hardware watchpoints.  The check
only examines the processor type to determine if it supports hardware
watchpoints.

The PowerPC processors support hardware watchpoints with the
exception of Power 9. The hardware watchpoint support is disabled on
Power 9.  The test skip_hw_watchpoint_tests must be used to correctly
determine if the PowerPC processor supports hardware watchpoints.

This patch replaces the [target_info exists gdb,no_hardware_watchpoints]
with the skip_hw_watchpoint_tests_p check.  With the patch, the test runs
on Power 9 with hardware watchpoint force-disabled.  The test runs on
all other PowerPC processors with and without hardware watchpoints
enabled.

The patch has been tested on Power 9 to verify the test only runs with
hardware breakpoints disabled.  The patch has been tested on X86-64 with
no regression failures.  The test fails on Power 8 and Power 10 due to
an internal GDB error due to resource management.  The resource management
issue will be addressed in another patch.
---
 gdb/testsuite/gdb.base/watchpoint.exp | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/gdb/testsuite/gdb.base/watchpoint.exp b/gdb/testsuite/gdb.base/watchpoint.exp
index 01abff5336a..736a0f905e5 100644
--- a/gdb/testsuite/gdb.base/watchpoint.exp
+++ b/gdb/testsuite/gdb.base/watchpoint.exp
@@ -15,6 +15,13 @@
 
 # This file was written by Fred Fish. (fnf@cygnus.com)
 
+# The skip_hw_watchpoint_tests checks if watchpoints are supported by the
+# processor.  On PowerPC, the check runs a small test program under gdb
+# to determine if the Power processor supports HW watchpoints.  The check
+# must be done before starting the test so as to not disrupt the execution
+# of the actual test.
+
+set skip_hw_watchpoint_tests_p [skip_hw_watchpoint_tests]
 
 standard_testfile
 
@@ -624,13 +631,14 @@ proc test_watch_location {} {
 proc test_wide_location_1 {} {
     global no_hw
     global gdb_prompt
+    global skip_hw_watchpoint_tests_p
 
     # This test watches two words on most 32-bit ABIs, and one word on
     # most 64-bit ABIs.
 
     # Platforms where the target can't watch such a large region
     # should clear hw_expected below.
-    if { $no_hw || [target_info exists gdb,no_hardware_watchpoints]
+    if { $no_hw || $skip_hw_watchpoint_tests_p
          || [istarget arm*-*-*]
          || ([istarget powerpc*-*-*] && ![is_lp64_target])} {
 	set hw_expected 0
@@ -671,13 +679,14 @@ proc test_wide_location_1 {} {
 proc test_wide_location_2 {} {
     global no_hw
     global gdb_prompt
+    global skip_hw_watchpoint_tests_p
 
     # This test watches four words on most 32-bit ABIs, and two words
     # on 64-bit ABIs.
 
     # Platforms where the target can't watch such a large region
     # should clear hw_expected below.
-    if { $no_hw || [target_info exists gdb,no_hardware_watchpoints]
+    if { $no_hw || $skip_hw_watchpoint_tests_p
          || [istarget arm*-*-*]
          || [istarget powerpc*-*-*]} {
 	set hw_expected 0
@@ -794,6 +803,7 @@ proc test_inaccessible_watchpoint {} {
 
 proc test_no_hw_watchpoints {} {
     global testfile
+    global skip_hw_watchpoint_tests_p
 
     clean_restart $testfile
 
@@ -839,7 +849,7 @@ proc test_no_hw_watchpoints {} {
 
 
     # Re-enable hardware watchpoints if necessary.
-    if ![target_info exists gdb,no_hardware_watchpoints] {
+    if {!$skip_hw_watchpoint_tests_p} {
         gdb_test_no_output "set can-use-hw-watchpoints 1" ""
     }
 }
@@ -891,8 +901,9 @@ proc test_watchpoint_in_big_blob {} {
 
 proc test_watch_register_location {} {
     global no_hw
+    global skip_hw_watchpoint_tests_p
 
-    if {!$no_hw && ![target_info exists gdb,no_hardware_watchpoints]} {
+    if {!$no_hw && !$skip_hw_watchpoint_tests_p} {
 	# Non-memory read/access watchpoints are not supported, they would
 	# require software read/access watchpoint support (which is not
 	# currently available).
@@ -916,10 +927,11 @@ test_no_hw_watchpoints
 proc do_tests {} {
     global testfile
     global no_hw
+    global skip_hw_watchpoint_tests_p
 
     clean_restart $testfile
 
-    if {$no_hw || [target_info exists gdb,no_hardware_watchpoints]} {
+    if {$no_hw || $skip_hw_watchpoint_tests_p} {
 	gdb_test_no_output "set can-use-hw-watchpoints 0"\
 	    "disable fast watches, 1"
     }
@@ -939,7 +951,7 @@ proc do_tests {} {
     # `initialize' anymore.
     clean_restart $testfile
 
-    if {$no_hw || [target_info exists gdb,no_hardware_watchpoints]} {
+    if {$no_hw || $skip_hw_watchpoint_tests_p} {
 	gdb_test_no_output "set can-use-hw-watchpoints 0" \
 	    "disable fast watches, 2"
     }
@@ -977,7 +989,7 @@ proc do_tests {} {
 # watchpoints force-disabled.
 
 do_tests
-if ![target_info exists gdb,no_hardware_watchpoints] {
+if {!$skip_hw_watchpoint_tests_p} {
     with_test_prefix "no-hw" {
 	set no_hw 1
 	do_tests
-- 
2.37.2

Re: [PATCH] PowerPC, fix gdb.base/watchpoint.exp on Power 9

[Ulrich Weigand]

Carl Love <cel@us.ibm.com> wrote:

>PowerPC, fix gdb.base/watchpoint.exp on Power 9

This is OK.

Thanks,
Ulrich