re PR middle-end/40022 (Alpine miscompilation)

2009-05-05  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/40022
	* tree-ssa-phiprop.c (struct phiprop_d): Exchange vop_stmt for
	the only vuse.
	(phivn_valid_p): Fix tuplification error, simplify.
	(phiprop_insert_phi): Add dumps.
	(propagate_with_phi): Simplify.

	* gcc.c-torture/execute/pr40022.c: New testcase.

From-SVN: r147128

gcc/ChangeLog

 2009-05-05  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/40022
+	* tree-ssa-phiprop.c (struct phiprop_d): Exchange vop_stmt for
+	the only vuse.
+	(phivn_valid_p): Fix tuplification error, simplify.
+	(phiprop_insert_phi): Add dumps.
+	(propagate_with_phi): Simplify.
+
+2009-05-05  Richard Guenther  <rguenther@suse.de>
+
 	PR middle-end/40023
 	* builtins.c (gimplify_va_arg_expr): Properly build the
 	address.

gcc/testsuite/ChangeLog

 2009-05-05  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/40022
+	* gcc.c-torture/execute/pr40022.c: New testcase.
+
+2009-05-05  Richard Guenther  <rguenther@suse.de>
+
 	PR middle-end/40023
 	* gcc.c-torture/compile/pr40023.c: New testcase.
 

gcc/testsuite/gcc.c-torture/execute/pr40022.c

+extern void abort (void);
+
+struct A
+{
+  struct A *a;
+};
+
+struct B
+{
+  struct A *b;
+};
+
+__attribute__((noinline))
+struct A *
+foo (struct A *x)
+{
+  asm volatile ("" : : "g" (x) : "memory");
+  return x;
+}
+
+__attribute__((noinline))
+void
+bar (struct B *w, struct A *x, struct A *y, struct A *z)
+{
+  struct A **c;
+  c = &w->b;
+  *c = foo (x);
+  while (*c)
+    c = &(*c)->a;
+  *c = foo (y);
+  while (*c)
+    c = &(*c)->a;
+  *c = foo (z);
+}
+
+struct B d;
+struct A e, f, g;
+
+int
+main (void)
+{
+  f.a = &g;
+  bar (&d, &e, &f, 0);
+  if (d.b == 0
+      || d.b->a == 0
+      || d.b->a->a == 0
+      || d.b->a->a->a != 0)
+    abort ();
+  return 0;
+}
+

gcc/tree-ssa-phiprop.c

@@ -90,12 +90,12 @@ along with GCC; see the file COPYING3.  If not see
 
 
 /* Structure to keep track of the value of a dereferenced PHI result
-   and the set of virtual operands used for that dereference.  */
+   and the virtual operand used for that dereference.  */
 
 struct phiprop_d
 {
   tree value;
-  gimple vop_stmt;
+  tree vuse;
 };
 
 /* Verify if the value recorded for NAME in PHIVN is still valid at
@@ -104,34 +104,27 @@ struct phiprop_d
 static bool
 phivn_valid_p (struct phiprop_d *phivn, tree name, basic_block bb)
 {
-  gimple vop_stmt = phivn[SSA_NAME_VERSION (name)].vop_stmt;
-  tree vuse;
+  tree vuse = phivn[SSA_NAME_VERSION (name)].vuse;
+  gimple use_stmt;
+  imm_use_iterator ui2;
+  bool ok = true;
 
-  /* The def stmts of all virtual uses need to be post-dominated
-     by bb.  */
-  if ((vuse = gimple_vuse (vop_stmt)))
-    {
-      gimple use_stmt;
-      imm_use_iterator ui2;
-      bool ok = true;
+  /* The def stmts of the virtual uses need to be dominated by bb.  */
+  gcc_assert (vuse != NULL_TREE);
 
-      FOR_EACH_IMM_USE_STMT (use_stmt, ui2, vuse)
+  FOR_EACH_IMM_USE_STMT (use_stmt, ui2, vuse)
+    {
+      /* If BB does not dominate a VDEF, the value is invalid.  */
+      if ((gimple_vdef (use_stmt) != NULL_TREE
+	   || gimple_code (use_stmt) == GIMPLE_PHI)
+	  && !dominated_by_p (CDI_DOMINATORS, gimple_bb (use_stmt), bb))
 	{
-	  /* If BB does not dominate a VDEF, the value is invalid.  */
-	  if (((is_gimple_assign (use_stmt)
-	        && gimple_vdef (use_stmt))
-	       || gimple_code (use_stmt) == GIMPLE_PHI)
-	      && !dominated_by_p (CDI_DOMINATORS, gimple_bb (use_stmt), bb))
-	    {
-	      ok = false;
-	      BREAK_FROM_IMM_USE_STMT (ui2);
-	    }
+	  ok = false;
+	  BREAK_FROM_IMM_USE_STMT (ui2);
 	}
-      if (!ok)
-	return false;
     }
 
-  return true;
+  return ok;
 }
 
 /* Insert a new phi node for the dereference of PHI at basic_block
@@ -154,6 +147,12 @@ phiprop_insert_phi (basic_block bb, gimple phi, gimple use_stmt,
   res = gimple_assign_lhs (use_stmt);
   SSA_NAME_DEF_STMT (res) = new_phi = create_phi_node (res, bb);
 
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "Inserting PHI for result of load ");
+      print_gimple_stmt (dump_file, use_stmt, 0, 0);
+    }
+
   /* Add PHI arguments for each edge inserting loads of the
      addressable operands.  */
   FOR_EACH_EDGE (e, ei, bb->preds)
@@ -171,8 +170,19 @@ phiprop_insert_phi (basic_block bb, gimple phi, gimple use_stmt,
 	}
 
       if (TREE_CODE (old_arg) == SSA_NAME)
-	/* Reuse a formerly created dereference.  */
-	new_var = phivn[SSA_NAME_VERSION (old_arg)].value;
+	{
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "  for edge defining ");
+	      print_generic_expr (dump_file, PHI_ARG_DEF_FROM_EDGE (phi, e), 0);
+	      fprintf (dump_file, " reusing PHI result ");
+	      print_generic_expr (dump_file,
+				  phivn[SSA_NAME_VERSION (old_arg)].value, 0);
+	      fprintf (dump_file, "\n");
+	    }
+	  /* Reuse a formerly created dereference.  */
+	  new_var = phivn[SSA_NAME_VERSION (old_arg)].value;
+	}
       else
 	{
 	  gcc_assert (TREE_CODE (old_arg) == ADDR_EXPR);
@@ -188,9 +198,15 @@ phiprop_insert_phi (basic_block bb, gimple phi, gimple use_stmt,
 	  gimple_assign_set_lhs (tmp, new_var);
 
 	  gsi_insert_on_edge (e, tmp);
-
 	  update_stmt (tmp);
-	  mark_symbols_for_renaming (tmp);
+
+	  if (dump_file && (dump_flags & TDF_DETAILS))
+	    {
+	      fprintf (dump_file, "  for edge defining ");
+	      print_generic_expr (dump_file, PHI_ARG_DEF_FROM_EDGE (phi, e), 0);
+	      fprintf (dump_file, " inserting load ");
+	      print_gimple_stmt (dump_file, tmp, 0, 0);
+	    }
 	}
 
       add_phi_arg (new_phi, new_var, e);
@@ -198,6 +214,9 @@ phiprop_insert_phi (basic_block bb, gimple phi, gimple use_stmt,
 
   update_stmt (new_phi);
 
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    print_gimple_stmt (dump_file, new_phi, 0, 0);
+
   return res;
 }
 
@@ -270,6 +289,7 @@ propagate_with_phi (basic_block bb, gimple phi, struct phiprop_d *phivn,
   phi_inserted = false;
   FOR_EACH_IMM_USE_STMT (use_stmt, ui, ptr)
     {
+      gimple def_stmt;
       tree vuse;
 
       /* Check whether this is a load of *ptr.  */
@@ -281,17 +301,15 @@ propagate_with_phi (basic_block bb, gimple phi, struct phiprop_d *phivn,
 	    && !stmt_can_throw_internal (use_stmt)))
 	continue;
 
-      /* Check if we can move the loads.  The def stmts of all virtual uses
-	 need to be post-dominated by bb.  */
-      if ((vuse = gimple_vuse (use_stmt)) != NULL_TREE)
-	{
-	  gimple def_stmt = SSA_NAME_DEF_STMT (vuse);
-	  if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
-	      && (gimple_bb (def_stmt) == bb
-		  || !dominated_by_p (CDI_DOMINATORS,
-				      bb, gimple_bb (def_stmt))))
-	    goto next;
-	}
+      /* Check if we can move the loads.  The def stmt of the virtual use
+	 needs to be in a different basic block dominating bb.  */
+      vuse = gimple_vuse (use_stmt);
+      def_stmt = SSA_NAME_DEF_STMT (vuse);
+      if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
+	  && (gimple_bb (def_stmt) == bb
+	      || !dominated_by_p (CDI_DOMINATORS,
+				  bb, gimple_bb (def_stmt))))
+	goto next;
 
       /* Found a proper dereference.  Insert a phi node if this
 	 is the first load transformation.  */
@@ -301,7 +319,7 @@ propagate_with_phi (basic_block bb, gimple phi, struct phiprop_d *phivn,
 
 	  /* Remember the value we created for *ptr.  */
 	  phivn[SSA_NAME_VERSION (ptr)].value = res;
-	  phivn[SSA_NAME_VERSION (ptr)].vop_stmt = use_stmt;
+	  phivn[SSA_NAME_VERSION (ptr)].vuse = vuse;
 
 	  /* Remove old stmt.  The phi is taken care of by DCE, if we
 	     want to delete it here we also have to delete all intermediate