PR tree-optimization/45830

	* stmt.c (expand_switch_using_bit_tests_p): New function.
	(expand_case): Use it.
	* tree.h (expand_switch_using_bit_tests_p): New prototype.
	* tree-switch-conversion.c (struct switch_conv_info): Add
	bit_test_uniq, bit_test_count and bit_test_bb fields.
	(check_range): Fix a comment.
	(check_process_case): Compute bit_test_uniq and bit_test_count.
	(create_temp_arrays): Use XCNEWVEC, merge 3 arrays into one
	allocation.
	(free_temp_arrays): Use XDELETEVEC, adjust for the 3 arrays merging.
	(constructor_contains_same_values_p): Use FOR_EACH_VEC_ELT.
	(array_value_type): New function.
	(build_one_array): Use it, if it returned different type,
	fold_convert all constructor fields and convert back to the
	wider type in the generated code.
	(process_switch): Initialize bit_test_uniq, bit_test_count and
	bit_test_bb fields.  Don't optimize if expand_switch_using_bit_tests_p
	returned true.

	* gcc.target/i386/pr45830.c: New test.
	* gcc.c-torture/execute/pr45830.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@166966 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 20 insertions, 8 deletions

diff --git a/gcc/stmt.c b/gcc/stmt.c
index e24ed4ebb31..e045330ef31 100644
--- a/gcc/stmt.c
+++ b/gcc/stmt.c
@@ -2250,6 +2250,25 @@ emit_case_bit_tests (tree index_type, tree index_expr, tree minval,
 #define HAVE_tablejump 0
 #endif
 
+/* Return true if a switch should be expanded as a bit test.
+   INDEX_EXPR is the index expression, RANGE is the difference between
+   highest and lowest case, UNIQ is number of unique case node targets
+   not counting the default case and COUNT is the number of comparisons
+   needed, not counting the default case.  */
+bool
+expand_switch_using_bit_tests_p (tree index_expr, tree range,
+				 unsigned int uniq, unsigned int count)
+{
+  return (CASE_USE_BIT_TESTS
+	  && ! TREE_CONSTANT (index_expr)
+	  && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
+	  && compare_tree_int (range, 0) > 0
+	  && lshift_cheap_p ()
+	  && ((uniq == 1 && count >= 3)
+	      || (uniq == 2 && count >= 5)
+	      || (uniq == 3 && count >= 6)));
+}
+
 /* Terminate a case (Pascal/Ada) or switch (C) statement
    in which ORIG_INDEX is the expression to be tested.
    If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
@@ -2384,14 +2403,7 @@ expand_case (gimple stmt)
       /* Try implementing this switch statement by a short sequence of
 	 bit-wise comparisons.  However, we let the binary-tree case
 	 below handle constant index expressions.  */
-      if (CASE_USE_BIT_TESTS
-	  && ! TREE_CONSTANT (index_expr)
-	  && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
-	  && compare_tree_int (range, 0) > 0
-	  && lshift_cheap_p ()
-	  && ((uniq == 1 && count >= 3)
-	      || (uniq == 2 && count >= 5)
-	      || (uniq == 3 && count >= 6)))
+      if (expand_switch_using_bit_tests_p (index_expr, range, uniq, count))
 	{
 	  /* Optimize the case where all the case values fit in a
 	     word without having to subtract MINVAL.  In this case,