re PR tree-optimization/67859 (ICE on valid code at -O2 and -O3 on x86_64-linux-gnu)

2015-10-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/67859
	* tree-ssa-pre.c (create_expression_by_pieces): Properly
	discard not inserted stmts.

	* gcc.dg/torture/pr67859.c: New testcase.

From-SVN: r228519

gcc/ChangeLog

+2015-10-06  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67859
+	* tree-ssa-pre.c (create_expression_by_pieces): Properly
+	discard not inserted stmts.
+
 2015-10-06  Jonathan Wakely  <jwakely@redhat.com>
 
 	* doc/extend.texi (Template Instantiation): Reorder options and

gcc/testsuite/ChangeLog

+2015-10-06  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/67859
+	* gcc.dg/torture/pr67859.c: New testcase.
+
 2015-10-05  Kirill Yukhin  <kirill.yukhin@intel.com>
 
 	* gcc.target/i386/builtin_target.c: Add check for AES and PCLMUL.

gcc/testsuite/gcc.dg/torture/pr67859.c

+/* { dg-do compile } */
+
+int a, b, c;
+
+void
+fn1 ()
+{
+  b = c ? 0 : 1 << a;
+  b |= 0x9D7A5FD9;
+  for (;;)
+    {
+      int d = 1;
+      b &= (unsigned) d;
+    }
+}

gcc/tree-ssa-pre.c

@@ -2897,11 +2897,16 @@ create_expression_by_pieces (basic_block block, pre_expr expr,
 
   folded = gimple_convert (&forced_stmts, exprtype, folded);
 
-  /* If everything simplified to an exisiting SSA name or constant just
-     return that.  */
-  if (gimple_seq_empty_p (forced_stmts)
-      || is_gimple_min_invariant (folded))
+  /* If there is nothing to insert, return the simplified result.  */
+  if (gimple_seq_empty_p (forced_stmts))
     return folded;
+  /* If we simplified to a constant return it and discard eventually
+     built stmts.  */
+  if (is_gimple_min_invariant (folded))
+    {
+      gimple_seq_discard (forced_stmts);
+      return folded;
+    }
 
   gcc_assert (TREE_CODE (folded) == SSA_NAME);