Updated spirv-tools.

3rdparty/spirv-tools/source/opt/loop_descriptor.cpp

@@ -754,6 +754,10 @@ bool Loop::FindNumberOfIterations(const Instruction* induction,
 // |step_value| is NOT cleanly divisible then we add one to the sum.
 int64_t Loop::GetIterations(SpvOp condition, int64_t condition_value,
                             int64_t init_value, int64_t step_value) const {
+  if (step_value == 0) {
+    return 0;
+  }
+
   int64_t diff = 0;
 
   switch (condition) {