[PATCH, PR 45934 3/6] More robust compute_complex_ancestor_jump_func

[Martin Jambor <mjambor@suse.cz>]

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Hi,

compute_complex_ancestor_jump_func tries to match a pattern like this:

     if (obj_2(D) != 0B)
       goto <bb 3>;
     else
       goto <bb 4>;

   <bb 3>:
     iftmp.1_3 = &obj_2(D)->D.1762;

   <bb 4>:
     # iftmp.1_1 = PHI <iftmp.1_3(3), 0B(2)>
     D.1879_6 = middleman_1 (iftmp.1_1, i_5(D));
     return D.1879_6;  */

At some point while working at the devirtualization issues I have seen
this failing because the zero was the zeroth parameter in the phi
node.  I think it is necessary for some of the new testcases to work
but I am not really sure any more, I only remembered when I was
splitting the big patch into separate ones.

I did not bootstrap this patch separately but it did pas bootstrap and
testsuite on x86_64-linux and make check-c++ on i686 together with the
rest.

Thanks,

Martin


2010-11-30  Martin Jambor  <mjambor@suse.cz>

	* ipa-prop.c (compute_complex_ancestor_jump_func): Work also if the
	zero is the first phi parameter.

Index: icln/gcc/ipa-prop.c
===================================================================
--- icln.orig/gcc/ipa-prop.c
+++ icln/gcc/ipa-prop.c
@@ -461,11 +461,15 @@ compute_complex_ancestor_jump_func (stru
   tree tmp, parm, expr;
   int index, i;
 
-  if (gimple_phi_num_args (phi) != 2
-      || !integer_zerop (PHI_ARG_DEF (phi, 1)))
+  if (gimple_phi_num_args (phi) != 2)
     return;
 
-  tmp = PHI_ARG_DEF (phi, 0);
+  if (integer_zerop (PHI_ARG_DEF (phi, 1)))
+    tmp = PHI_ARG_DEF (phi, 0);
+  else if (integer_zerop (PHI_ARG_DEF (phi, 0)))
+    tmp = PHI_ARG_DEF (phi, 1);
+  else
+    return;
   if (TREE_CODE (tmp) != SSA_NAME
       || SSA_NAME_IS_DEFAULT_DEF (tmp)
       || !POINTER_TYPE_P (TREE_TYPE (tmp))