[PING] [PATCH v2] Fix -var-update for registers in frames 1 and up
Don Breazeal
donb@codesourcery.com
Mon Jul 11 14:48:00 GMT 2016
ping
On 6/20/2016 8:31 AM, Don Breazeal wrote:
> On 6/13/2016 2:54 PM, Don Breazeal wrote:
>> This is an updated version of a patch to fix access to registers
>> for frames other than the current frame via var-update. The piece
>> of the patch affecting GDB proper has been completely re-written.
>> It changes the initialization of varobj->root->frame in varobj_create
>> so that existing mechanisms (with minimal changes) select the correct
>> frame and provide correct register values from -var-update.
>>
>> In addition, the new test for this functionality has been expanded
>> to cover an analogous case using floating variable objects, and
>> several tests have been updated to account for the fact that with
>> the new initialization, -var-create and -var-list-children now
>> provide a thread-id field where previously they didn't.
>>
>> Thanks
>> --Don
>>
>> ------------
>> This patch fixes a problem with using the MI -var-update command
>> to access the values of registers in frames other than the current
>> frame. The patch includes a test that demonstrates the problem:
>>
>> * run so there are several frames on the stack
>> * create a fixed varobj for $pc in each frame, #'s 1 and above
>> * step one instruction, to modify the value of $pc
>> * call -var-update for each of the previously created varobjs
>> to verify that they are not reported as having changed.
>>
>> Without the patch, the -var-update command reported that $pc for all
>> frames 1 and above had changed to the value of $pc in frame 0.
>>
>> When a varobj is created by -var-create, varobj->root->frame should
>> be set to specified frame. Then for a subsequent -var-update,
>> varobj.c:check_scope can use varobj->root->frame to select the
>> right frame based on the type of varobj.
>>
>> The problem is that for register expressions varobj->root->frame is not
>> set correctly. This frame tracking is done using the global
>> 'innermost_block' which is set in the various parser files (for example
>> c-exp.y). However, this is not set for register expressions.
>>
>> The fix is to change the initialization of innermost_block in
>> varobj_create from NULL to the global block, as returned by
>> block_global_block. Then varobj_create sets varobj->root->frame
>> for register varobjs, and value_of_root_1 can check for the
>> global block when determining whether the variable is in-scope
>> and select the frame appropriately.
>>
>> A side-effect of this change is that for register varobjs and some
>> global variable varobjs, the output of -var-create now includes the
>> thread-id field. The rationale for this is as follow: if we ask for a
>> particular expression in a particular frame, that implies a particular
>> thread. Thus including the thread-id is correct behavior, and the
>> test results have been updated accordingly.
>>
>> In addition there is a new test, gdb.mi/mi-frame-regs.exp, which
>> performs the test described in the bullet list above as well as a
>> similar test using a floating variable object to represent $pc.
>>
>> We attempted a couple alternative solutions:
>> * a special case in varobj_update to select the frame was not ideal
>> because it didn't use the existing mechanisms to select the frame.
>> * setting innermost_block in write_dollar_variable had side-effects
>> in the CLI that would have required special case code.
>>
>> Tested on x86_64 Linux native, no regressions.
>>
>> gdb/testsuite/ChangeLog:
>> 2016-06-13 Don Breazeal <dbreazea@my.domain.org>
>>
>> * gdb.ada/mi_interface.exp: Add thread-id field to expected
>> output of -var-create and -var-list-children.
>> * gdb.ada/mi_var_array.exp: Add thread-id field to expected
>> output of -var-list-children.
>> * gdb.mi/mi-break.exp (test_error): Add thread-id field to
>> expected output of -var-create.
>> * gdb.mi/mi-frame-regs.exp: New test script.
>> * gdb.mi/mi-var-cmd.exp: Add thread-id field to expected
>> output of -var-create.
>> * gdb.mi/mi-var-create-rtti.exp: Likewise.
>>
>> gdb/ChangeLog:
>> 2016-06-13 Don Breazeal <donb@codesourcery.com>
>> Andrew Burgess <andrew.burgess@embecosm.com>
>>
>> * varobj.c (varobj_create): Initialize innermost_block to
>> the global block instead of NULL.
>> (new_root_variable): Initialize the thread_id and next
>> fields.
>> (value_of_root_1): Set within_scope if the variable's
>> valid_block field is the global block.
>>
>> ---
>> gdb/testsuite/gdb.ada/mi_interface.exp | 4 +-
>> gdb/testsuite/gdb.ada/mi_var_array.exp | 2 +-
>> gdb/testsuite/gdb.mi/mi-break.exp | 2 +-
>> gdb/testsuite/gdb.mi/mi-frame-regs.exp | 183 ++++++++++++++++++++++++++++
>> gdb/testsuite/gdb.mi/mi-var-cmd.exp | 4 +-
>> gdb/testsuite/gdb.mi/mi-var-create-rtti.exp | 2 +-
>> gdb/varobj.c | 8 +-
>> 7 files changed, 196 insertions(+), 9 deletions(-)
>>
>> diff --git a/gdb/testsuite/gdb.ada/mi_interface.exp b/gdb/testsuite/gdb.ada/mi_interface.exp
>> index 6000ec8..b948cd5 100644
>> --- a/gdb/testsuite/gdb.ada/mi_interface.exp
>> +++ b/gdb/testsuite/gdb.ada/mi_interface.exp
>> @@ -44,9 +44,9 @@ mi_continue_to_line \
>> "stop at start of main Ada procedure"
>>
>> mi_gdb_test "-var-create ggg1 * ggg1" \
>> - "\\^done,name=\"ggg1\",numchild=\"1\",value=\"{...}\",type=\"<ref> pck.gadatatype\",has_more=\"0\"" \
>> + "\\^done,name=\"ggg1\",numchild=\"1\",value=\"{...}\",type=\"<ref> pck.gadatatype\",thread-id=\"1\",has_more=\"0\"" \
>> "Create ggg1 varobj"
>>
>> mi_gdb_test "-var-list-children 1 ggg1" \
>> - "\\^done,numchild=\"1\",children=\\\[child={name=\"ggg1.i\",exp=\"i\",numchild=\"0\",value=\"42\",type=\"integer\"}\\\],has_more=\"0\"" \
>> + "\\^done,numchild=\"1\",children=\\\[child={name=\"ggg1.i\",exp=\"i\",numchild=\"0\",value=\"42\",type=\"integer\",thread-id=\"1\"}\\\],has_more=\"0\"" \
>> "list ggg1's children"
>> diff --git a/gdb/testsuite/gdb.ada/mi_var_array.exp b/gdb/testsuite/gdb.ada/mi_var_array.exp
>> index c648e7e..c02d4c9 100644
>> --- a/gdb/testsuite/gdb.ada/mi_var_array.exp
>> +++ b/gdb/testsuite/gdb.ada/mi_var_array.exp
>> @@ -48,5 +48,5 @@ mi_gdb_test "-var-create vta * vta" \
>> "Create bt varobj"
>>
>> mi_gdb_test "-var-list-children vta" \
>> - "\\^done,numchild=\"2\",children=\\\[child={name=\"vta.n\",exp=\"n\",numchild=\"0\",type=\"bar\\.int\"},child={name=\"vta.f\",exp=\"f\",numchild=\"0\",type=\"array \\(1 .. n\\) of character\"}\\\],.*" \
>> + "\\^done,numchild=\"2\",children=\\\[child={name=\"vta.n\",exp=\"n\",numchild=\"0\",type=\"bar\\.int\",thread-id=\"1\"},child={name=\"vta.f\",exp=\"f\",numchild=\"0\",type=\"array \\(1 .. n\\) of character\",thread-id=\"1\"}\\\],.*" \
>> "list vta's children"
>> diff --git a/gdb/testsuite/gdb.mi/mi-break.exp b/gdb/testsuite/gdb.mi/mi-break.exp
>> index 85f328d..bdd43e0 100644
>> --- a/gdb/testsuite/gdb.mi/mi-break.exp
>> +++ b/gdb/testsuite/gdb.mi/mi-break.exp
>> @@ -213,7 +213,7 @@ proc test_error {} {
>> # containing function call, the internal breakpoint created to handle
>> # function call would be reported, messing up MI output.
>> mi_gdb_test "-var-create V * return_1()" \
>> - "\\^done,name=\"V\",numchild=\"0\",value=\"1\",type=\"int\",has_more=\"0\"" \
>> + "\\^done,name=\"V\",numchild=\"0\",value=\"1\",type=\"int\",thread-id=\"1\",has_more=\"0\"" \
>> "create varobj for function call"
>>
>> mi_gdb_test "-var-update *" \
>> diff --git a/gdb/testsuite/gdb.mi/mi-frame-regs.exp b/gdb/testsuite/gdb.mi/mi-frame-regs.exp
>> new file mode 100644
>> index 0000000..45f81d6
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.mi/mi-frame-regs.exp
>> @@ -0,0 +1,183 @@
>> +# Copyright 1999-2016 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/>.
>> +
>> +# Test essential Machine interface (MI) operations
>> +#
>> +# Verify that -var-update will provide the correct values for floating
>> +# and fixed varobjs that represent the pc register.
>> +#
>> +
>> +load_lib mi-support.exp
>> +set MIFLAGS "-i=mi"
>> +
>> +standard_testfile basics.c
>> +
>> +if {[gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
>> + executable {debug}] != "" } then {
>> + untested mi-frame-regs.exp
>> + return -1
>> +}
>> +
>> +# Return the address of the specified breakpoint.
>> +
>> +proc breakpoint_address {bpnum} {
>> + global hex
>> + global expect_out
>> + global mi_gdb_prompt
>> +
>> + send_gdb "info breakpoint $bpnum\n"
>> + gdb_expect {
>> + -re ".*($hex).*$mi_gdb_prompt$" {
>> + return $expect_out(1,string)
>> + }
>> + -re ".*$mi_gdb_prompt$" {
>> + return ""
>> + }
>> + timeout {
>> + return ""
>> + }
>> + }
>> +}
>> +
>> +# Test that a floating varobj representing $pc will provide the
>> +# correct value via -var-update as the program stops at
>> +# breakpoints in different functions.
>> +
>> +proc do_floating_varobj_test {} {
>> + global srcfile
>> + global hex
>> + global expect_out
>> +
>> + gdb_exit
>> + if {[mi_gdb_start]} then {
>> + continue
>> + }
>> +
>> + with_test_prefix "floating" {
>> + mi_run_to_main
>> +
>> + # Create a floating varobj for $pc.
>> + mi_gdb_test "-var-create --thread 1 --frame 0 - @ \$pc" \
>> + "\\^done,.*value=\"$hex.*" \
>> + "create varobj for pc in frame 0"
>> +
>> + set nframes 4
>> + for {set i 1} {$i < $nframes} {incr i} {
>> +
>> + # Run to a breakpoint in each callee function in succession.
>> + # Note that we can't use mi_runto because we need the
>> + # breakpoint to be persistent, so we can use its address.
>> + set bpnum [expr $i + 1]
>> + mi_create_breakpoint \
>> + "basics.c:callee$i" \
>> + "insert breakpoint at basics.c:callee$i" \
>> + -number $bpnum -func callee$i -file ".*basics.c"
>> +
>> + mi_execute_to "exec-continue" "breakpoint-hit" \
>> + "callee$i" ".*" ".*${srcfile}" ".*" \
>> + { "" "disp=\"keep\"" } "breakpoint hit"
>> +
>> + # Get the value of $pc from the floating varobj.
>> + mi_gdb_test "-var-update 1 var1" \
>> + "\\^done,.*value=\"($hex) .*" \
>> + "-var-update for frame $i"
>> + set pcval $expect_out(3,string)
>> +
>> + # Get the address of the current breakpoint.
>> + set bpaddr [breakpoint_address $bpnum]
>> + if {$bpaddr == ""} then {
>> + unresolved "get address of breakpoint $bpnum"
>> + return
>> + }
>> +
>> + # Check that the addresses are the same.
>> + if {[expr $bpaddr != $pcval]} then {
>> + fail "\$pc does not equal address of breakpoint"
>> + } else {
>> + pass "\$pc equals address of breakpoint"
>> + }
>> + }
>> + }
>> +}
>> +
>> +# Create a varobj for the pc register in each of the frames other
>> +# than frame 0.
>> +
>> +proc var_create_regs {nframes} {
>> + global hex
>> +
>> + for {set i 1} {$i < $nframes} {incr i} {
>> + mi_gdb_test "-var-create --thread 1 --frame $i - \* \$pc" \
>> + "\\^done,.*value=\"$hex.*" \
>> + "create varobj for pc in frame $i"
>> + }
>> +}
>> +
>> +# Check that -var-update reports that the value of the pc register
>> +# for each of the frames 1 and above is reported as unchanged.
>> +
>> +proc var_update_regs {nframes} {
>> +
>> + for {set i 1} {$i < $nframes} {incr i} {
>> + mi_gdb_test "-var-update 1 var$i" \
>> + "\\^done,(changelist=\\\[\\\])" \
>> + "pc unchanged in -var-update for frame $i"
>> + }
>> +}
>> +
>> +# Test that fixed varobjs representing $pc in different stack frames
>> +# will provide the correct value via -var-update after the program
>> +# counter changes (without substantially changing the stack).
>> +
>> +proc do_fixed_varobj_test {} {
>> + global srcfile
>> +
>> + gdb_exit
>> + if {[mi_gdb_start]} then {
>> + continue
>> + }
>> +
>> + with_test_prefix "fixed" {
>> + mi_run_to_main
>> +
>> + # Run to the function 'callee3' so we have several frames.
>> + mi_create_breakpoint "basics.c:callee3" \
>> + "insert breakpoint at basics.c:callee3" \
>> + -number 2 -func callee3 -file ".*basics.c"
>> +
>> + mi_execute_to "exec-continue" "breakpoint-hit" \
>> + "callee3" ".*" ".*${srcfile}" ".*" \
>> + { "" "disp=\"keep\"" } "breakpoint hit"
>> +
>> + # At the breakpoint in callee3 there are 4 frames. Create a
>> + # varobj for the pc in each of frames 1 and above.
>> + set nframes 4
>> + var_create_regs $nframes
>> +
>> + # Step one instruction to change the program counter.
>> + mi_execute_to "exec-next-instruction" "end-stepping-range" \
>> + "callee3" ".*" ".*${srcfile}" ".*" "" \
>> + "next instruction in callee3"
>> +
>> + # Check that -var-update reports that the values are unchanged.
>> + var_update_regs $nframes
>> + }
>> +}
>> +
>> +do_fixed_varobj_test
>> +do_floating_varobj_test
>> +
>> +mi_gdb_exit
>> +return 0
>> diff --git a/gdb/testsuite/gdb.mi/mi-var-cmd.exp b/gdb/testsuite/gdb.mi/mi-var-cmd.exp
>> index 558cd6c..68e3cf8 100644
>> --- a/gdb/testsuite/gdb.mi/mi-var-cmd.exp
>> +++ b/gdb/testsuite/gdb.mi/mi-var-cmd.exp
>> @@ -381,7 +381,7 @@ mi_gdb_test "-var-update *" \
>> "assign same value to func (update)"
>>
>> mi_gdb_test "-var-create array_ptr * array_ptr" \
>> - "\\^done,name=\"array_ptr\",numchild=\"1\",value=\"$hex <array>\",type=\"int \\*\",has_more=\"0\"" \
>> + "\\^done,name=\"array_ptr\",numchild=\"1\",value=\"$hex <array>\",type=\"int \\*\",thread-id=\"1\",has_more=\"0\"" \
>> "create global variable array_ptr"
>>
>> mi_gdb_test "-var-assign array_ptr array2" \
>> @@ -608,7 +608,7 @@ mi_check_varobj_value F 7 "check F inside callee"
>> # A varobj we fail to read during -var-update should be considered
>> # out of scope.
>> mi_gdb_test "-var-create null_ptr * **0" \
>> - {\^done,name="null_ptr",numchild="0",value=".*",type="int",has_more="0"} \
>> + {\^done,name="null_ptr",numchild="0",value=".*",type="int",thread-id="1"has_more="0"} \
>> "create null_ptr"
>>
>> # Allow this to succeed, if address zero is readable, although it
>> diff --git a/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp b/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp
>> index 3bcb36c..a8cc76f 100644
>> --- a/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp
>> +++ b/gdb/testsuite/gdb.mi/mi-var-create-rtti.exp
>> @@ -49,6 +49,6 @@ mi_gdb_test "-gdb-set print object on" ".*"
>> # We use a explicit cast to (void *) as that is the
>> # type that caused the bug this testcase is testing for.
>> mi_gdb_test "-var-create sp1 * ((void*)\$sp)" \
>> - "\\^done,name=\"sp1\",numchild=\"0\",value=\"$hex\",type=\"void \\*\",has_more=\"0\"" \
>> + "\\^done,name=\"sp1\",numchild=\"0\",value=\"$hex\",type=\"void \\*\",thread-id=\"1\",has_more=\"0\"" \
>> "-var-create sp1 * \$sp"
>> gdb_exit
>> diff --git a/gdb/varobj.c b/gdb/varobj.c
>> index 6f56cba..1e3f192 100644
>> --- a/gdb/varobj.c
>> +++ b/gdb/varobj.c
>> @@ -323,7 +323,7 @@ varobj_create (char *objname,
>> }
>>
>> p = expression;
>> - innermost_block = NULL;
>> + innermost_block = block_global_block (block);
>> /* Wrap the call to parse expression, so we can
>> return a sensible error. */
>> TRY
>> @@ -2103,6 +2103,8 @@ new_root_variable (void)
>> var->root->floating = 0;
>> var->root->rootvar = NULL;
>> var->root->is_valid = 1;
>> + var->root->thread_id = 0;
>> + var->root->next = NULL;
>>
>> return var;
>> }
>> @@ -2268,7 +2270,9 @@ value_of_root_1 (struct varobj **var_handle)
>> back_to = make_cleanup_restore_current_thread ();
>>
>> /* Determine whether the variable is still around. */
>> - if (var->root->valid_block == NULL || var->root->floating)
>> + if (var->root->valid_block == NULL
>> + || BLOCK_SUPERBLOCK (var->root->valid_block) == NULL
>> + || var->root->floating)
>> within_scope = 1;
>> else if (var->root->thread_id == 0)
>> {
>>
>
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