permit promotion with cmp

enzyme/Enzyme/GradientUtils.cpp

diff --git a/enzyme/Enzyme/GradientUtils.cpp b/enzyme/Enzyme/GradientUtils.cpp
index 2c79e89..793bc2a 100644
--- a/enzyme/Enzyme/GradientUtils.cpp
+++ b/enzyme/Enzyme/GradientUtils.cpp
@@ -8369,6 +8369,8 @@
         if (auto I = dyn_cast<Instruction>(u))
           todo.push_back(std::make_pair(I, (Value *)cur));
       }
+    } else if (isa<ICmpInst>(cur)) {
+      continue;
     } else if (auto load = dyn_cast<LoadInst>(cur)) {
 
       // If loaded value is an int or pointer, may need