Consider invariant loads in cache analysis (rust-lang#559)

* Invariant loads

* alloc

* Fix for LLVM 9

Co-authored-by: Ubuntu <[email protected]>

Author: wsmoses

enzyme/Enzyme/EnzymeLogic.cpp

@@ -240,6 +240,14 @@ struct CacheAnalysis {
         if (PT->getAddressSpace() == 13)
           return false;
 
+#if LLVM_VERSION_MAJOR >= 10
+    if (li.hasMetadata(LLVMContext::MD_invariant_load))
+      return false;
+#else
+    if (li.getMetadata(LLVMContext::MD_invariant_load))
+      return false;
+#endif
+
     // Find the underlying object for the pointer operand of the load
     // instruction.
     auto obj =
@@ -390,7 +398,7 @@ struct CacheAnalysis {
       return {};
     }
 
-    if (isCertainPrintMallocOrFree(Fn)) {
+    if (isCertainPrintMallocOrFree(Fn) || isAllocationFunction(*Fn, TLI)) {
       return {};
     }