Saturate overflows return from SCEV in ranger.

bounds_of_var_in_loop is returning an overflowed int, which is causing
us to create a range for which we can't compare the bounds causing
an ICE in verify_range.

Overflowed bounds cause compare_values() to return -2, which we
don't handle in verify_range.

We don't represent overflowed ranges in irange, so this patch just
saturates any overflowed end-points to MIN or MAX.

gcc/ChangeLog:

	PR tree-optimization/97501
	* gimple-range.cc (gimple_ranger::range_of_ssa_name_with_loop_info):
	Saturate overflows returned from SCEV.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr97501.c: New test.

2 files changed, 16 insertions, 2 deletions

diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index e4864ba..ed9609b 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -1146,9 +1146,9 @@ gimple_ranger::range_of_ssa_name_with_loop_info (irange &r, tree name,
       // ?? We could do better here.  Since MIN/MAX can only be an
       // SSA, SSA +- INTEGER_CST, or INTEGER_CST, we could easily call
       // the ranger and solve anything not an integer.
-      if (TREE_CODE (min) != INTEGER_CST)
+      if (TREE_CODE (min) != INTEGER_CST || TREE_OVERFLOW (min))
 	min = vrp_val_min (type);
-      if (TREE_CODE (max) != INTEGER_CST)
+      if (TREE_CODE (max) != INTEGER_CST || TREE_OVERFLOW (max))
 	max = vrp_val_max (type);
       r.set (min, max);
     }
diff --git a/gcc/testsuite/gcc.dg/pr97501.c b/gcc/testsuite/gcc.dg/pr97501.c
new file mode 100644
index 0000000..aedac83
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97501.c
@@ -0,0 +1,14 @@
+// { dg-do compile }
+// { dg-options "-O2" }
+
+static int c = 0;
+
+int main() {
+  int b = 0;
+  if (c) {
+  for (;; b--)
+    do
+      b++;
+    while (b);
+  }
+}