I'm trying to see if gcc can provide more information that I can use to create Control Flow Graph from a C source code and then use it to check which path is taken by an executed test case from Gcov .gcov output. So far my best candidate is using -fdump-tree-cfg with lineno option (-fdump-tree-cfg-lineno) but the resulting file is still limiting for me since node informations are separated for each function. Something like this:
;; Function main (main, funcdef_no=13, decl_uid=3054, cgraph_uid=13, symbol_order=13)
Removing basic block 7
Merging blocks 5 and 6
;; 1 loops found
;;
;; Loop 0
;; header 0, latch 1
;; depth 0, outer -1
;; nodes: 0 1 2 3 4 5 6
;; 2 succs { 3 4 }
;; 3 succs { 5 }
;; 4 succs { 5 }
;; 5 succs { 6 }
;; 6 succs { 1 }
main ()
{
int number;
int D.3066;
<bb 2> [0.00%]:
[evenodd.c:7:5] printf ([evenodd.c:7:12] "\nEnter a number: ");
[evenodd.c:8:5] scanf ([evenodd.c:8:11] "%d", [evenodd.c:8:5] &number);
[evenodd.c:10:2] number.0_1 = number;
[evenodd.c:10:2] checkNegative (number.0_1);
[evenodd.c:12:17] number.1_2 = number;
[evenodd.c:12:17] number.2_3 = (unsigned int) number.1_2;
[evenodd.c:12:17] _4 = number.2_3 & 1;
[evenodd.c:12:7] if (_4 == 0)
goto <bb 3>; [0.00%]
else
goto <bb 4>; [0.00%]
<bb 3> [0.00%]:
[evenodd.c:13:9] number.3_5 = number;
[evenodd.c:13:9] printf ([evenodd.c:13:16] "%d is Even\n", number.3_5);
[0:0] goto <bb 5>; [0.00%]
<bb 4> [0.00%]:
[evenodd.c:15:9] number.4_6 = number;
[evenodd.c:15:9] printf ([evenodd.c:15:16] "%d is Odd\n", number.4_6);
<bb 5> [0.00%]:
[evenodd.c:18:9] D.3066 = 0;
number = {CLOBBER};
<L4> [0.00%]:
return D.3066;
}
;; Function checkNegative (checkNegative, funcdef_no=14, decl_uid=3057, cgraph_uid=14, symbol_order=14)
;; 1 loops found
;;
;; Loop 0
;; header 0, latch 1
;; depth 0, outer -1
;; nodes: 0 1 2 3 4 5
;; 2 succs { 3 4 }
;; 3 succs { 5 }
;; 4 succs { 5 }
;; 5 succs { 1 }
checkNegative (int number)
{
<bb 2> [0.00%]:
[evenodd.c:23:4] if (number < 0)
goto <bb 3>; [0.00%]
else
goto <bb 4>; [0.00%]
<bb 3> [0.00%]:
[evenodd.c:24:9] printf ([evenodd.c:24:16] "%d is Negative\n", number);
[0:0] goto <bb 5>; [0.00%]
<bb 4> [0.00%]:
[evenodd.c:26:9] printf ([evenodd.c:26:16] "%d is Positive\n", number);
<bb 5> [0.00%]:
[evenodd.c:28:1] return;
}
This means that my parser need to recognize each function call inside the main function and then merge their node information which is a pretty daunting task for me.
So I came accross the -graph option for -fdump-tree from this documentation but I have no idea how to use it. As the doc describe it:
‘graph’
For each of the other indicated dump files (-fdump-rtl-pass),
dump a representation of the control flow graph suitable for
viewing with GraphViz to file.passid.pass.dot. Each function in
the file is pretty-printed as a subgraph, so that GraphViz can
render them all in a single plot.
This option currently only works for RTL dumps, and the RTL
is always dumped in slim form.
I don't know how GraphViz works but since it's able to render all function's subgraph as a single plot (I assume that it means all subgraph is merged with the main graph as a single graph), it means that the information provided by -graph is more complete and ease the process of creating the Control Flow Graph.
Since I can't understand what it means, I tried using the option as it is (-fdump-tree-cfg-lineno-graph) but the result is still the same as -fdump-tree-cfg-lineno's result.
How do I use it?
