unswitch: Fold case label lo/hi values to index type [PR105770]

The following testcase ICEs because we use different types in comparison,
idx has int type, while CASE_LOW has char type.

While I believe all CASE_{LOW,HIGH} in the same switch have to use the same
or compatible type, the index expression can have a promoted type as happens
in this testcase.  Other spots that handle switches do such foldings too.

2022-06-01  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/105770
	* tree-ssa-loop-unswitch.cc (find_unswitching_predicates_for_bb): Cast
	CASE_LOW and CASE_HIGH to TREE_TYPE (idx) before comparisons with idx.

	* gcc.dg/pr105770.c: New test.

diff --git a/gcc/testsuite/gcc.dg/pr105770.c b/gcc/testsuite/gcc.dg/pr105770.c
new file mode 100644 (file)
index 0000000..c1e0140
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr105770.c
@@ -0,0 +1,19 @@
+/* PR tree-optimization/105770 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -funswitch-loops -fno-tree-forwprop" } */
+
+char a;
+
+void
+foo (void)
+{
+  while (a)
+    switch (a)
+      {
+      case ' ':
+      case '\t':
+       return;
+      }
+
+  __builtin_unreachable ();
+}

diff --git a/gcc/tree-ssa-loop-unswitch.cc b/gcc/tree-ssa-loop-unswitch.cc
index ad1d05ccdffec5a05c4bcb6968ce3736c35b893a..2b6013e9d6963dc9f738797ee14d5c7bc74103dd 100644 (file)
--- a/gcc/tree-ssa-loop-unswitch.cc
+++ b/gcc/tree-ssa-loop-unswitch.cc
@@ -494,6 +494,7 @@ find_unswitching_predicates_for_bb (basic_block bb, class loop *loop,
     {
       unsigned nlabels = gimple_switch_num_labels (stmt);
       tree idx = gimple_switch_index (stmt);
+      tree idx_type = TREE_TYPE (idx);
       if (!gimple_range_ssa_p (idx) || nlabels < 1)
        return;
       /* Index must be invariant.  */
@@ -525,16 +526,18 @@ find_unswitching_predicates_for_bb (basic_block bb, class loop *loop,
          if (CASE_HIGH (lab) != NULL_TREE)
            {
              tree cmp1 = fold_build2 (GE_EXPR, boolean_type_node, idx,
-                                      CASE_LOW (lab));
+                                      fold_convert (idx_type,
+                                                    CASE_LOW (lab)));
              tree cmp2 = fold_build2 (LE_EXPR, boolean_type_node, idx,
-                                      CASE_HIGH (lab));
+                                      fold_convert (idx_type,
+                                                    CASE_HIGH (lab)));
              cmp = fold_build2 (BIT_AND_EXPR, boolean_type_node, cmp1, cmp2);
              lab_range.set (CASE_LOW (lab), CASE_HIGH (lab));
            }
          else
            {
              cmp = fold_build2 (EQ_EXPR, boolean_type_node, idx,
-                                CASE_LOW (lab));
+                                fold_convert (idx_type, CASE_LOW (lab)));
              lab_range.set (CASE_LOW (lab));
            }