PR 22037

	* tree-cfg.c (replace_uses_by): Call mark_new_vars_to_rename.
	(tree_merge_blocks): Propagate anything allowed by
	may_propagate_copy.
	Clarify documentation.
	* passes.c (execute_todo): If cleanup_tree_cfg invalidated the
	SSA form, schedule an update if necessary.

testsuite/ChangeLog

	PR 22037
	* g++.dg/tree-ssa/pr22037.C:


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@102740 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 43 insertions, 7 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9f14805c80d..6b62ce56129 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2005-08-04  Diego Novillo  <dnovillo@redhat.com>
+
+	PR 22037
+	* tree-cfg.c (replace_uses_by): Call mark_new_vars_to_rename.
+	(tree_merge_blocks): Propagate anything allowed by
+	may_propagate_copy.
+	Clarify documentation.
+	* passes.c (execute_todo): If cleanup_tree_cfg invalidated the
+	SSA form, schedule an update if necessary.
+
 2005-08-04  Gerald Pfeifer  <gerald@pfeifer.com>
 
 	* doc/install.texi (Binaries): Remove broken link to
diff --git a/gcc/passes.c b/gcc/passes.c
index 76f5da3988b..f199989f986 100644
--- a/gcc/passes.c
+++ b/gcc/passes.c
@@ -684,6 +684,15 @@ execute_todo (struct tree_opt_pass *pass, unsigned int flags, bool use_required)
 	cleanup_tree_cfg_loop ();
       else
 	cleanup_tree_cfg ();
+
+      /* When cleanup_tree_cfg merges consecutive blocks, it may
+	 perform some simplistic propagation when removing single
+	 valued PHI nodes.  This propagation may, in turn, cause the
+	 SSA form to become out-of-date (see PR 22037).  So, even
+	 if the parent pass had not scheduled an SSA update, we may
+	 still need to do one.  */
+      if (!(flags & TODO_update_ssa_any) && need_ssa_update_p ())
+	flags |= TODO_update_ssa;
     }
 
   if (flags & TODO_update_ssa_any)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0f668570fbd..cd35f624ce2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2005-08-04  Diego Novillo  <dnovillo@redhat.com>
+
+	PR 22037
+	* g++.dg/tree-ssa/pr22037.C:
+
 2005-08-04  Richard Henderson  <rth@redhat.com>
 
 	* gcc.dg/tree-ssa/update-cunroll.c: Fix mistakes in
diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr22037.C b/gcc/testsuite/g++.dg/tree-ssa/pr22037.C
new file mode 100644
index 00000000000..11fc1b0389a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/pr22037.C
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+extern double sqrt (double) throw (); 
+ 
+void foo(double& d, int n) 
+{ 
+  double e=0; 
+  for(int i=0; i<n; i++); 
+  for(int i=0; i<n; i++) e=1; 
+  d = sqrt(e); 
+ 
+  for(int i=0; i<n; i++); 
+}
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 096da092151..b5a0696ddec 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -1273,7 +1273,7 @@ replace_uses_by (tree name, tree val)
       if (TREE_CODE (rhs) == ADDR_EXPR)
 	recompute_tree_invarant_for_addr_expr (rhs);
 
-      update_stmt (stmt);
+      mark_new_vars_to_rename (stmt);
     }
 
   VEC_free (tree, heap, stmts);
@@ -1304,18 +1304,15 @@ tree_merge_blocks (basic_block a, basic_block b)
   if (dump_file)
     fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
 
-  /* Remove the phi nodes.  */
+  /* Remove all single-valued PHI nodes from block B of the form
+     V_i = PHI <V_j> by propagating V_j to all the uses of V_i.  */
   bsi = bsi_last (a);
   for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
     {
       tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
       tree copy;
       
-      if (!may_propagate_copy (def, use)
-	  /* Propagating pointers might cause the set of vops for statements
-	     to be changed, and thus require ssa form update.  */
-	  || (is_gimple_reg (def)
-	      && POINTER_TYPE_P (TREE_TYPE (def))))
+      if (!may_propagate_copy (def, use))
 	{
 	  gcc_assert (is_gimple_reg (def));
 
@@ -1330,6 +1327,7 @@ tree_merge_blocks (basic_block a, basic_block b)
 	}
       else
 	replace_uses_by (def, use);
+
       remove_phi_node (phi, NULL);
     }