Add --param case-values-threshold

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@175878 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 16 insertions, 1 deletions

diff --git a/gcc/stmt.c b/gcc/stmt.c
index 1a9f9e505da..38e1e285234 100644
--- a/gcc/stmt.c
+++ b/gcc/stmt.c
@@ -53,6 +53,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "alloc-pool.h"
 #include "pretty-print.h"
 #include "bitmap.h"
+#include "params.h"
 
 
 /* Functions and data structures for expanding case statements.  */
@@ -2270,6 +2271,20 @@ expand_switch_using_bit_tests_p (tree index_expr, tree range,
 	      || (uniq == 3 && count >= 6)));
 }
 
+/* Return the smallest number of different values for which it is best to use a
+   jump-table instead of a tree of conditional branches.  */
+
+static unsigned int
+case_values_threshold (void)
+{
+  unsigned int threshold = PARAM_VALUE (PARAM_CASE_VALUES_THRESHOLD);
+
+  if (threshold == 0)
+    threshold = targetm.case_values_threshold ();
+
+  return threshold;
+}
+
 /* 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
@@ -2424,7 +2439,7 @@ expand_case (gimple stmt)
 	 If the switch-index is a constant, do it this way
 	 because we can optimize it.  */
 
-      else if (count < targetm.case_values_threshold ()
+      else if (count < case_values_threshold ()
 	       || compare_tree_int (range,
 				    (optimize_insn_for_size_p () ? 3 : 10) * count) > 0
 	       /* RANGE may be signed, and really large ranges will show up