re PR tree-optimization/86945 (BUG with optimisation of select case statement in gfortran)

2018-08-22  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/86945
	* tree-cfg.c (generate_range_test): Use unsigned arithmetic.

	* gcc.dg/torture/pr86945.c: New testcase.

From-SVN: r263761

gcc/ChangeLog

+2018-08-22  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/86945
+	* tree-cfg.c (generate_range_test): Use unsigned arithmetic.
+
 2018-08-22  Alexandre Oliva <oliva@adacore.com>
 
 	* config/rs6000/rs6000.c (SMALL_DATA_RELOC, SMALL_DATA_REG): Add

gcc/testsuite/ChangeLog

+2018-08-22  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/86945
+	* tree-cfg.c (generate_range_test): Use unsigned arithmetic.
+
 2018-08-21  Janne Blomqvist  <jb@gcc.gnu.org>
 
 	* gfortran.dg/nan_1.f90: Remove tests that test MAX/MIN with NaNs.

gcc/testsuite/gcc.dg/torture/pr86945.c

+/* { dg-do run } */
+
+void __attribute__((noinline,noipa))
+foo(int id)
+{
+  switch (id)
+    {
+    case (-__INT_MAX__ - 1)...-1:
+      __builtin_abort ();
+    default:;
+    }
+}
+
+int main()
+{
+  foo(1);
+  return 0;
+}

gcc/tree-cfg.c

@@ -9131,20 +9131,16 @@ generate_range_test (basic_block bb, tree index, tree low, tree high,
   tree type = TREE_TYPE (index);
   tree utype = unsigned_type_for (type);
 
-  low = fold_convert (type, low);
-  high = fold_convert (type, high);
+  low = fold_convert (utype, low);
+  high = fold_convert (utype, high);
 
-  tree tmp = make_ssa_name (type);
-  gassign *sub1
-    = gimple_build_assign (tmp, MINUS_EXPR, index, low);
+  gimple_seq seq = NULL;
+  index = gimple_convert (&seq, utype, index);
+  *lhs = gimple_build (&seq, MINUS_EXPR, utype, index, low);
+  *rhs = const_binop (MINUS_EXPR, utype, high, low);
 
-  *lhs = make_ssa_name (utype);
-  gassign *a = gimple_build_assign (*lhs, NOP_EXPR, tmp);
-
-  *rhs = fold_build2 (MINUS_EXPR, utype, high, low);
   gimple_stmt_iterator gsi = gsi_last_bb (bb);
-  gsi_insert_before (&gsi, sub1, GSI_SAME_STMT);
-  gsi_insert_before (&gsi, a, GSI_SAME_STMT);
+  gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT);
 }
 
 /* Emit return warnings.  */