On Monday 28 April 2014 02:46 PM, Richard Biener wrote:
On Sat, Apr 26, 2014 at 4:07 PM, Richard Biener
<richard.guent...@gmail.com> wrote:
On April 26, 2014 12:31:34 PM CEST, Swati Rathi <swatira...@cse.iitb.ac.in>
wrote:
On Friday 25 April 2014 11:11 PM, Richard Biener wrote:
On April 25, 2014 5:54:09 PM CEST, Swati Rathi
<swatira...@cse.iitb.ac.in> wrote:
Hello,
I am trying to print points-to information for SSA variables as
below.
for (i = 1; i < num_ssa_names; i++)
{
tree ptr = ssa_name (i);
struct ptr_info_def *pi;
if (ptr == NULL_TREE
|| SSA_NAME_IN_FREE_LIST (ptr))
continue;
pi = SSA_NAME_PTR_INFO (ptr);
if (pi)
dump_points_to_info_for (file, ptr);
}
-------------------------------------------------------------
My test program is given below :
int main()
{
int *p, i, j;
void (*fp1)();
if (i)
{
p = &i;
fp1 = fun1;
}
else
{
p = &j;
fp1 = fun2;
}
fp1();
printf ("\n%d %d\n", *p, i);
return 0;
}
-------------------------------------------------------------
I get the output as :-
p_1, points-to vars: { i j }
fp1_2, points-to vars: { }
-------------------------------------------------------------
Why is the pointees for function pointer not getting dumped?
It's just not saved.
Can we modify the code to preserve values for function pointer SSA
names?
Sure.
Index: gcc/tree-ssa-structalias.c
===================================================================
--- gcc/tree-ssa-structalias.c (revision 209782)
+++ gcc/tree-ssa-structalias.c (working copy)
@@ -6032,7 +6032,8 @@ set_uids_in_ptset (bitmap into, bitmap f
if (TREE_CODE (vi->decl) == VAR_DECL
|| TREE_CODE (vi->decl) == PARM_DECL
- || TREE_CODE (vi->decl) == RESULT_DECL)
+ || TREE_CODE (vi->decl) == RESULT_DECL
+ || TREE_CODE (vi->decl) == FUNCTION_DECL)
{
/* If we are in IPA mode we will not recompute points-to
sets after inlining so make sure they stay valid. */
Thanks a lot. :) This is of great help.
note that there isn't a convenient way to go back from a bit in the
points-to bitmap to the actual FUNCTION_DECL refered to.
The bitmap is set by identifying the bit using DECL_PT_UID.
For variables, referenced_var_lookup returns the associated variable.
For FUNCTION_DECL's, all we need to do is store a mapping between uid
and FUNCTION_DECL.
Is this correct?
Richard.
What is the reason that it is not preserved for function pointers?
Nobody uses this information.
Another alternative approach would be to replicate the code (of
pass_ipa_pta) and use the information before deleting it.
Is there any other way to access this information?
You can of course recompute it when needed.
Richard.
How can I access this information?
Regards,
Swati
