Re: [PATCH] switch lowering: limit number of cluster attemps

[Martin Liška]

On 9/25/20 3:52 PM, Jakub Jelinek wrote:

On Fri, Sep 25, 2020 at 11:13:06AM +0200, Martin Liška wrote:

--- a/gcc/tree-switch-conversion.c
+++ b/gcc/tree-switch-conversion.c
@@ -1268,6 +1268,15 @@ jump_table_cluster::can_be_handled (const vec<cluster *> 
&clusters,
    if (range == 0)
      return false;

+ unsigned HOST_WIDE_INT lhs = 100 * range;

+  if (lhs < range)
+    return false;

If this test is meant to detect when 100 * range has overflowed,
then I think it is insufficient.
Perhaps do
   if (range > HOST_WIDE_INT_M1U / 100)
     return false;

   unsigned HOST_WIDE_INT lhs = 100 * range;
instead?

Yes, I'll add the check.

Thanks,
Martin

        Jakub