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Which MI behavior is correct ?


Hello GDB experts,

I wonder if somebody can help me to understand which
GDB MI behavior is supposed to be correct.

I've included the test case, the MI commands used, and
the outputs from two debuggers: the native FC5 Linux-X86

GNU gdb Red Hat Linux (6.3.0.0-1.134.fc5rh)

and ours

GNU gdb 6.5 Xtensa Tools 7.1.0-development

Our GNU gdb 6.5 is consistent with the top of the FSF tree.


PROBLEM DESCRIPTION: ====================

When we hit the breakpoint inside f11() second time:

In case of 6.3 we have :

228^done,changelist=[{name="var3",in_scope="true",type_changed="false"}]
(gdb)
229^done,changelist=[{name="var4",in_scope="true",type_changed="false"}]
(gdb)
230^done,value="3"
(gdb)
231^done,value="2"
(gdb)

In in case of 6.5+ we have :

228^done,changelist=[{name="var3",in_scope="false"}]
(gdb)
229^done,changelist=[{name="var4",in_scope="false"}]
(gdb)
230^done,value="2"
(gdb)
231^done,value="1"
(gdb)

So "var3" and "var4" are out of scope.

Our GUI front-end relies on the 6.3-like behavior, which is consistent with
what we had in our previous releases based on GNU gdb 5.2.1.

QUESTIONS
=========

1) Is 6.5(+)-style behavior incorrect ?

If it is correct:

- Are we supposed to recreate variables each time we enter the function ?
- Is this efficient ?


2) Where can I find a good documentation describing these aspects of GDB MI ?
All docs I found on the Internet weren't quite helpful.


Thanks in advance for any of your help.

-- Maxim












100-gdb-set confirm off
101-gdb-set width 0
102-gdb-set height 0
103-interpreter-exec console echo
104-gdb-show prompt
file exe
200-break-insert create_var.cxx:14
201-break-insert create_var.cxx:7
202-data-list-register-names
203-stack-info-depth
204-break-insert -t main
run
206-stack-info-depth
207-stack-list-frames 0 1
208-data-list-changed-registers
209-stack-list-arguments 0 0 0
210-stack-list-locals 0
211-var-create - * a
212-var-create - * b
213-var-evaluate-expression var2
214-var-evaluate-expression var1
215-exec-continue
216-stack-info-depth
217-stack-list-frames 0 2
218-data-list-changed-registers
219-stack-list-arguments 0 0 0
220-stack-list-locals 0
221-var-create - * b
222-var-create - * a
223-var-evaluate-expression var4
224-var-evaluate-expression var3
225-exec-continue
226-stack-info-depth
227-stack-list-frames 0 2
228-var-update var3
229-var-update var4
230-var-evaluate-expression var4
231-var-evaluate-expression var3

(gdb) 
100^done
(gdb) 
101^done
(gdb) 
102^done
(gdb) 
103^done
(gdb) 
104^done,value="(gdb) "
(gdb) 
&"file exe\n"
~"Using host libthread_db library \"/lib/libthread_db.so.1\".\n"
^done
(gdb) 
200^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x0804845f",func="f1(int)",file="create_var.cxx",line="14",times="0"}
(gdb) 
201^done,bkpt={number="2",type="breakpoint",disp="keep",enabled="y",addr="0x08048443",func="f11(int)",file="create_var.cxx",line="7",times="0"}
(gdb) 
202^done,register-names=["eax","ecx","edx","ebx","esp","ebp","esi","edi","eip","eflags","cs","ss","ds","es","fs","gs","st0","st1","st2","st3","st4","st5","st6","st7","fctrl","fstat","ftag","fiseg","fioff","foseg","fooff","fop","xmm0","xmm1","xmm2","xmm3","xmm4","xmm5","xmm6","xmm7","mxcsr","orig_eax","mm0","mm1","mm2","mm3","mm4","mm5","mm6","mm7"]
(gdb) 
&"mi_cmd_stack_info_depth: No stack.\n"
203^error,msg="mi_cmd_stack_info_depth: No stack."
(gdb) 
204^done,bkpt={number="3",type="breakpoint",disp="del",enabled="y",addr="0x08048464",func="main",file="create_var.cxx",line="17",times="0"}
(gdb) 
&"run\n"
^done,thread-id="0",frame={addr="0x08048464",func="main",args=[],file="create_var.cxx",line="17"}
(gdb) 
206^done,depth="1"
(gdb) 
207^done,stack=[frame={level="0",addr="0x08048464",func="main",file="create_var.cxx",line="17"}]
(gdb) 
208^done,changed-registers=["0","1","2","3","4","5","6","8","9","10","11","12","13","15","24","26","40","41"]
(gdb) 
209^done,stack-args=[frame={level="0",args=[]}]
(gdb) 
210^done,locals=[name="a",name="b"]
(gdb) 
211^done,name="var1",numchild="0",type="int"
(gdb) 
212^done,name="var2",numchild="0",type="int"
(gdb) 
213^done,value="11553984"
(gdb) 
214^done,value="12808180"
(gdb) 
215^running
(gdb) 
215*stopped,reason="breakpoint-hit",bkptno="2",thread-id="0",frame={addr="0x08048443",func="f11",args=[{name="b",value="1"}],file="create_var.cxx",line="7"}
(gdb) 
216^done,depth="2"
(gdb) 
217^done,stack=[frame={level="0",addr="0x08048443",func="f11",file="create_var.cxx",line="7"},frame={level="1",addr="0x08048487",func="main",file="create_var.cxx",line="22"}]
(gdb) 
218^done,changed-registers=["0","1","4","5","8","9"]
(gdb) 
219^done,stack-args=[frame={level="0",args=[name="b"]}]
(gdb) 
220^done,locals=[name="a"]
(gdb) 
221^done,name="var3",numchild="0",type="int"
(gdb) 
222^done,name="var4",numchild="0",type="int"
(gdb) 
223^done,value="2"
(gdb) 
224^done,value="1"
(gdb) 
225^running
(gdb) 
225*stopped,reason="breakpoint-hit",bkptno="2",thread-id="0",frame={addr="0x08048443",func="f11",args=[{name="b",value="2"}],file="create_var.cxx",line="7"}
(gdb) 
226^done,depth="2"
(gdb) 
227^done,stack=[frame={level="0",addr="0x08048443",func="f11",file="create_var.cxx",line="7"},frame={level="1",addr="0x08048495",func="main",file="create_var.cxx",line="23"}]
(gdb) 
228^done,changelist=[{name="var3",in_scope="true",type_changed="false"}]
(gdb) 
229^done,changelist=[{name="var4",in_scope="true",type_changed="false"}]
(gdb) 
230^done,value="3"
(gdb) 
231^done,value="2"
(gdb) 
&"\n"
^done
(gdb) 
(gdb) 
100^done
(gdb) 
101^done
(gdb) 
102^done
(gdb) 
103^done
(gdb) 
104^done,value="(xt-gdb) "
(gdb) 
&"file exe\n"
^done
(gdb) 
200^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x40000978",func="f1(int)",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="14",times="0"}
(gdb) 
201^done,bkpt={number="2",type="breakpoint",disp="keep",enabled="y",addr="0x40000991",func="f11(int)",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="7",times="0"}
(gdb) 
202^done,register-names=["br","ar0","ar1","ar2","ar3","ar4","ar5","ar6","ar7","ar8","ar9","ar10","ar11","ar12","ar13","ar14","ar15","ar16","ar17","ar18","ar19","ar20","ar21","ar22","ar23","ar24","ar25","ar26","ar27","ar28","ar29","ar30","ar31","ar32","ar33","ar34","ar35","ar36","ar37","ar38","ar39","ar40","ar41","ar42","ar43","ar44","ar45","ar46","ar47","ar48","ar49","ar50","ar51","ar52","ar53","ar54","ar55","ar56","ar57","ar58","ar59","ar60","ar61","ar62","ar63","m0","m1","m2","m3","lbeg","lend","lcount","acclo","acchi","mmid","ddr","interrupt","intset","intclear","ccount","icount","ccompare0","ccompare1","epc1","epc2","epc3","excsave1","excsave2","excsave3","eps2","eps3","exccause","depc","excvaddr","windowbase","windowstart","sar","litbase","ps","intenable","dbreaka0","dbreakc0","dbreaka1","dbreakc1","ibreaka0","ibreaka1","ibreakenable","icountlevel","debugcause","cpenable","pc","a0","a1","a2","a3","a4","a5","a6","a7","a8","a9","a10","a11","a12","a13","a14","a15","b0","b1","b2","b3","b4","b5","b6","b7","b8","b9","b10","b11","b12","b13","b14","b15","psintlevel","psum","pswoe","psexcm","pscallinc","psowb","litbaddr","litben","acc","dbnum","fp"]
(gdb) 
&"No registers.\n"
203^error,msg="No registers."
(gdb) 
204^done,bkpt={number="3",type="breakpoint",disp="del",enabled="y",addr="0x40000937",func="main",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="19",times="0"}
(gdb) 
&"run\n"
~"Starting the ISS simulator.\n"
~"Switching to remote protocol\n"
~"Remote debugging using localhost:56386\n"
~"main () at create_var.cxx:19\n"
~"19\t\tint a=1;\n"
^done
(gdb) 
206^done,depth="1"
(gdb) 
207^done,stack=[frame={level="0",addr="0x40000937",func="main",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="19"}]
(gdb) 
208^done,changed-registers=["2","3","5","6","7","8","9","10","11","13","14","17","21","22","23","24","79","87","94","95","98","109","110","111","112","113","114","115","116","117","119","120","123","144","145","147","153"]
(gdb) 
209^done,stack-args=[frame={level="0",args=[]}]
(gdb) 
210^done,locals=[name="a",name="b"]
(gdb) 
211^done,name="var1",numchild="0",type="int"
(gdb) 
212^done,name="var2",numchild="0",type="int"
(gdb) 
213^done,value="0"
(gdb) 
214^done,value="0"
(gdb) 
215^running
(gdb) 
215*stopped,reason="breakpoint-hit",bkptno="2",thread-id="0",frame={addr="0x40000991",func="f11",args=[{name="b",value="1"}],file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="7"}
(gdb) 
216^done,depth="2"
(gdb) 
217^done,stack=[frame={level="0",addr="0x40000991",func="f11",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="7"},frame={level="1",addr="0x40000940",func="main",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="22"}]
(gdb) 
218^done,changed-registers=["13","14","15","16","17","79","94","95","98","110","111","112","114","115","116","117","119","120","121","122","123","147","153"]
(gdb) 
219^done,stack-args=[frame={level="0",args=[name="b"]}]
(gdb) 
220^done,locals=[name="a"]
(gdb) 
221^done,name="var3",numchild="0",type="int"
(gdb) 
222^done,name="var4",numchild="0",type="int"
(gdb) 
223^done,value="2"
(gdb) 
224^done,value="1"
(gdb) 
225^running
(gdb) 
225*stopped,reason="breakpoint-hit",bkptno="2",thread-id="0",frame={addr="0x40000991",func="f11",args=[{name="b",value="2"}],file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="7"}
(gdb) 
226^done,depth="2"
(gdb) 
227^done,stack=[frame={level="0",addr="0x40000991",func="f11",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="7"},frame={level="1",addr="0x40000947",func="main",file="create_var.cxx",fullname="/home/maxim/W/BUGS/PMAC_MI/create_var.cxx",line="23"}]
(gdb) 
228^done,changelist=[{name="var3",in_scope="false"}]
(gdb) 
229^done,changelist=[{name="var4",in_scope="false"}]
(gdb) 
230^done,value="2"
(gdb) 
231^done,value="1"
(gdb) 
&"\n"
^done
(gdb) 

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