PR61385: phiopt drops some PHIs

[Marc Glisse]

Hello,

apparently it is possible to have a PHI in the middle basic block of 
value_replacement, so I need to move it as well when I move the statement 
and remove the block.

Bootstrap and testsuite on x86_64-linux-gnu (re-running for various 
reasons but they had completed successfully yesterday).

2014-06-03  Marc Glisse  <marc.gli...@inria.fr>

        PR tree-optimization/61385
gcc/
        * tree-ssa-phiopt.c (value_replacement): Copy PHI nodes before
        removing the basic block.
gcc/testsuite/
        * gcc.dg/tree-ssa/pr61385.c: New file.

--
Marc GlisseIndex: gcc/testsuite/gcc.dg/tree-ssa/pr61385.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/pr61385.c     (revision 0)
+++ gcc/testsuite/gcc.dg/tree-ssa/pr61385.c     (working copy)
@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#define assert(x) if (!(x)) __builtin_abort ()
+
+int a, b, c, d, e, f, g;
+
+int
+fn1 ()
+{
+  int *h = &c;
+  for (; c < 1; c++)
+    {
+      int *i = &a, *k = &a;
+      f = 0;
+      if (b)
+       return 0;
+      if (*h)
+       {
+         int **j = &i;
+         *j = 0;
+         d = 0;
+       }
+      else
+       g = e = 0;
+      if (*h)
+       {
+         int **l = &k;
+         *l = &g;
+       }
+      d &= *h;
+      assert (k == &a || k);
+      assert (i);
+    }
+  return 0;
+}
+
+int
+main ()
+{
+  fn1 (); 
+  return 0;
+}
Index: gcc/tree-ssa-phiopt.c
===================================================================
--- gcc/tree-ssa-phiopt.c       (revision 211178)
+++ gcc/tree-ssa-phiopt.c       (working copy)
@@ -877,20 +877,39 @@ value_replacement (basic_block cond_bb,
           && operand_equal_for_phi_arg_p (rhs2, cond_lhs)
           && neutral_element_p (code_def, cond_rhs, true))
          || (arg1 == rhs2
              && operand_equal_for_phi_arg_p (rhs1, cond_lhs)
              && neutral_element_p (code_def, cond_rhs, false))
          || (operand_equal_for_phi_arg_p (arg1, cond_rhs)
              && (operand_equal_for_phi_arg_p (rhs2, cond_lhs)
                  || operand_equal_for_phi_arg_p (rhs1, cond_lhs))
              && absorbing_element_p (code_def, cond_rhs))))
     {
+      /* Move potential PHI nodes.  */
+      gimple_stmt_iterator psi = gsi_start_phis (middle_bb);
+      while (!gsi_end_p (psi))
+       {
+         gimple phi_moving = gsi_stmt (psi);
+         gimple newphi = create_phi_node (gimple_phi_result (phi_moving),
+                                          cond_bb);
+         int nargs = cond_bb->preds->length();
+         location_t loc = gimple_phi_arg_location (phi_moving, 0);
+         tree phi_arg = gimple_phi_arg_def (phi_moving, 0);
+         for (int i = 0; i < nargs; ++i)
+           {
+             edge e = (*cond_bb->preds)[i];
+             add_phi_arg (newphi, phi_arg, e, loc);
+           }
+         update_stmt (newphi);
+         gsi_remove (&psi, false);
+       }
+
       gsi = gsi_for_stmt (cond);
       gimple_stmt_iterator gsi_from = gsi_for_stmt (assign);
       gsi_move_before (&gsi_from, &gsi);
       replace_phi_edge_with_variable (cond_bb, e1, phi, lhs);
       return 2;
     }
 
   return 0;
 }