re PR tree-optimization/44977 (ice in propagate_rhs_into_lhs, at tree-ssa-dom.c:2728)

2010-07-20  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/44977
	* tree-ssa-dom.c (propagate_rhs_into_lhs): Do not create invalid
	SSA form.

	* gcc.dg/torture/pr44977.c: New testcase.

From-SVN: r162334

gcc/ChangeLog

 2010-07-20  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/44977
+	* tree-ssa-dom.c (propagate_rhs_into_lhs): Do not create invalid
+	SSA form.
+
+2010-07-20  Richard Guenther  <rguenther@suse.de>
+
 	* lto-symtab.c (lto_symtab_merge): Use gimple_types_compatible_p.
 	(lto_symtab_merge_decls_2): Likewise.
 	* gimple.h (gimple_types_compatible_p): Declare.

gcc/testsuite/ChangeLog

+2010-07-20  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/44977
+	* gcc.dg/torture/pr44977.c: New testcase.
+
 2010-07-20  Bingfeng Mei  <bmei@broadcom.com>
 
 	* gcc.dg/lto/20090313_0.c: Use dg-require-effective-target

gcc/testsuite/gcc.dg/torture/pr44977.c

+/* { dg-do compile } */
+/* { dg-options "-w" } */
+
+static unsigned short
+foo (unsigned short ui1, unsigned short ui2)
+{
+  return ui1 - ui2;
+}
+
+static unsigned short
+bar (unsigned ui1, unsigned short ui2)
+{
+  return ui1 + ui2;
+}
+
+struct S1
+{
+  const short f3;
+};
+int g_31;
+short g_67;
+struct S1 g_68[2][5][9][1][1] = {
+};
+
+int func_90 (int);
+
+int int329 (int * const *const int32p_81, short ** p_82)
+{
+  short l_169[8];
+  for (g_31 = 0; g_31 <= 0; g_31 = foo (g_31, 1))
+    {
+      short l_85;
+lbl_89:g_67 ^= l_85;
+       for (l_85 = 0; l_85 >= 0; l_85 = bar)
+	 if (g_31)
+	   goto lbl_89;
+       func_90 (1), g_68[0][2][2][0][0].f3, 0;
+    }
+  return l_169[6];
+}
+

gcc/tree-ssa-dom.c

@@ -2559,6 +2559,20 @@ propagate_rhs_into_lhs (gimple stmt, tree lhs, tree rhs, bitmap interesting_name
 	      continue;
 	    }
 
+	  /* It's not ok to propagate into the definition stmt of RHS.
+		<bb 9>:
+		  # prephitmp.12_36 = PHI <g_67.1_6(9)>
+		  g_67.1_6 = prephitmp.12_36;
+		  goto <bb 9>;
+	     While this is strictly all dead code we do not want to
+	     deal with this here.  */
+	  if (TREE_CODE (rhs) == SSA_NAME
+	      && SSA_NAME_DEF_STMT (rhs) == use_stmt)
+	    {
+	      all = false;
+	      continue;
+	    }
+
 	  /* Dump details.  */
 	  if (dump_file && (dump_flags & TDF_DETAILS))
 	    {