Cleanup allocation and remat (rust-lang#916)

* Cleanup allocation and remat

* fix

Author: wsmoses

enzyme/Enzyme/GradientUtils.cpp

@@ -7197,25 +7197,6 @@ void GradientUtils::computeForwardingProperties(Instruction *V) {
         break;
       case Intrinsic::memset: {
         bool first = true;
-#if LLVM_VERSION_MAJOR >= 14
-        for (auto &arg : II->args())
-#else
-        for (auto &arg : II->arg_operands())
-#endif
-        {
-          if (first) {
-            first = false;
-            break;
-          }
-          if (arg == prev) {
-            promotable = false;
-            shadowpromotable = false;
-            EmitWarning("NotPromotable", *cur, " Could not promote allocation ",
-                        *V, " due to memset use ", *cur);
-            break;
-          }
-          break;
-        }
         stores.insert(II);
         storingOps.insert(II);
         break;

enzyme/Enzyme/Utils.cpp

@@ -99,7 +99,8 @@ Function *getOrInsertExponentialAllocator(Module &M, Function *newFunc,
     IRBuilder<> B(BB);
     auto P = B.CreatePHI(i64, 1);
     CallInst *malloccall;
-    CreateAllocation(B, RT, P, "tapemem", &malloccall, nullptr)->getType();
+    Instruction *SubZero = nullptr;
+    CreateAllocation(B, RT, P, "tapemem", &malloccall, &SubZero)->getType();
     if (auto F = getFunctionFromCall(malloccall)) {
       custom = F->getName() != "malloc";
     }