re PR tree-optimization/44030 (error: SSA name in freelist but still referenced)

2010-05-08  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/44030
	* tree-ssa-pre.c (eliminate): Copy NECESSARY flag.  Set
	NECESSARY flag if we propagate from a inserted expression.

	* gcc.c-torture/compile/pr44030.c: New testcase.

From-SVN: r159186

gcc/ChangeLog

+2010-05-08  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/44030
+	* tree-ssa-pre.c (eliminate): Copy NECESSARY flag.  Set
+	NECESSARY flag if we propagate from a inserted expression.
+
 2010-05-08  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gimple.c (gimple_types_compatible_p) <ARRAY_TYPE>: Treat bounds of

gcc/testsuite/ChangeLog

+2010-05-08  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/44030
+	* gcc.c-torture/compile/pr44030.c: New testcase.
+
 2010-05-08  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gnat.dg/lto6.adb: New test.

gcc/testsuite/gcc.c-torture/compile/pr44030.c

+typedef int int32_t;
+typedef unsigned int uint32_t;
+static uint32_t
+safe_sub_func_uint32_t_u_u (uint32_t ui1, uint32_t ui2)
+{
+  return ui1 - ui2;
+}
+
+int32_t l_105[7];
+
+int32_t g_4;
+int32_t *g_54 = &g_4;
+int32_t *
+func (int32_t p_73, int32_t * p_74, int32_t p_75, int32_t * *p_76,
+      int32_t * *p_77)
+{
+lbl_110:for (g_4 = 0; g_4; g_4 = 1)
+    {
+    }
+  for (p_75 = -28; p_75; p_75 = safe_sub_func_uint32_t_u_u (p_75, 1))
+    {
+      if (g_4)
+        goto lbl_110;
+      *g_54 = 0;
+    }
+  return &l_105[5];
+}
+

gcc/tree-ssa-pre.c

@@ -4351,6 +4351,7 @@ eliminate (void)
 	    sprime = fold_convert (TREE_TYPE (res), sprime);
 	  stmt = gimple_build_assign (res, sprime);
 	  SSA_NAME_DEF_STMT (res) = stmt;
+	  gimple_set_plf (stmt, NECESSARY, gimple_plf (phi, NECESSARY));
 
 	  gsi2 = gsi_after_labels (b);
 	  gsi_insert_before (&gsi2, stmt, GSI_NEW_STMT);
@@ -4381,8 +4382,11 @@ eliminate (void)
 	  && single_imm_use (lhs, &use_p, &use_stmt)
 	  && may_propagate_copy (USE_FROM_PTR (use_p), rhs))
 	{
-	  SET_USE (use_p, gimple_assign_rhs1 (stmt));
+	  SET_USE (use_p, rhs);
 	  update_stmt (use_stmt);
+	  if (bitmap_bit_p (inserted_exprs, SSA_NAME_VERSION (lhs))
+	      && TREE_CODE (rhs) == SSA_NAME)
+	    gimple_set_plf (SSA_NAME_DEF_STMT (rhs), NECESSARY, true);
 	}
 
       /* If this is a store or a now unused copy, remove it.  */