Hi All,
I came across this python based plugin from the dehydra page and
was really excited to learn about this I feel this will be really powerful
and quick way of writing plugins into GCC to do various things. I was
trying to play around with GCC python plugin. I noticed something weird. I
just tried to dump gimple I see that I am missing goto statements,
E.g.
I am created a call back and the callback only proceeds when the pass is
*free_lang_data
At this stage I get the CFG and in each basic block I try to print the
Gimple statements in the basic blocks.
I am doing something similar to the following.
*def print_gimple_pass_execution_callback(p, fn):
if p.name == '*free_lang_data':
for cgn in gcc.get_callgraph_nodes():
if isinstance(cfn, gcc.Function):
contfg = cfn.cfg
for block in cfg.basic_blocks:
prev = fname + str(block.index) + "$start"
if isinstance(block.gimple, list) and block.gimple !=
[]:
for gimple in block.gimple:
print gimple*
I see gimple statements like
*D.1689 = i & 1;*
I also see labels but I do not see the goto.
I was looking deeper into the plugin source code and I see that the python
plugin creates a gimple statement iterator then gets the basic block from
that and processes each statement to wrap them in the python objects.
I wrote my own code to perform the equivalent.
*static unsigned print_exec(void)
{
unsigned i;
const_tree str, op;
basic_block bb;
gimple stmt;
gimple_stmt_iterator gsi;
FOR_EACH_BB(bb)
for (gsi=gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi))
{
stmt = gsi_stmt(gsi);
print_stmt(stmt);
}
return 0;
}*
I still see gimple statements but do not see the goto gimple statement
*i = 0;
D.1689_2 = (const char * restrict) &"Enter number : "[0];
printf (D.1689_2);
D.1690_3 = (const char * restrict) &"%d"[0];
scanf (D.1690_3, &i);
i.0_4 = i;
D.1692_5 = i.0_4 & 1;
D.1693_6 = (_Bool) D.1692_5;
if (D.1693_6 != 0)
success:
D.1696_8 = 0;
out:
D.1696_7 = -1;
return D.1696_1;*
My program is
*#include<stdio.h>
int main()
{
int i=0;
printf("Enter number : ");
scanf("%d",&i);
if(i%2)
goto out;
goto success;
success :
return 0;
out :
return -1;
}
*
But if I dump the gimple statements with
*gcc -fdump-tree-gimple goto.c *
I see all the Gimple Goto statements.
Given this and the fact that the program does what it is supposed to be
doing I believe I may be using the wrong pass or I may be doing something
wrong inside my plugin. I was hoping someone in this list can help me with
this issue.
I am really excited to play around with this tool. I know that the
GimpleGoto is not fully wrapped but I would be able to wrap it once I can
get the Goto statement from GCC.
I am using *gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5*)
Does anyone have any insight into why I am not getting the GimpleGoto
statements? Any help would be really helpful.
-----
Harie Srinivasa B.R.
