Generalize call cache behavior

Author: wsmoses

enzyme/Enzyme/AdjointGenerator.h

@@ -6487,7 +6487,8 @@ class AdjointGenerator
       // may load uncacheable data)
       //    Store and reload it
       if (Mode != DerivativeMode::ReverseModeCombined && subretused &&
-          !orig->doesNotAccessMemory()) {
+          (orig->mayWriteToMemory() ||
+           !gutils->legalRecompute(orig, ValueToValueMapTy(), nullptr))) {
         if (!gutils->unnecessaryIntermediates.count(orig)) {
           gutils->cacheForReverse(BuilderZ, newCall,
                                   getIndex(orig, CacheType::Self));

enzyme/Enzyme/Enzyme.cpp

@@ -816,10 +816,13 @@ class Enzyme : public ModulePass {
         if (Fn->getName().contains("__enzyme_call_inactive")) {
           InactiveCalls.insert(CI);
         }
-        if (F.getName() == "omp_get_max_threads" ||
-            F.getName() == "omp_get_thread_num") {
-          F.addFnAttr(Attribute::ReadOnly);
-          F.addFnAttr(Attribute::InaccessibleMemOnly);
+        if (Fn->getName() == "omp_get_max_threads" ||
+            Fn->getName() == "omp_get_thread_num") {
+          Fn->addFnAttr(Attribute::ReadOnly);
+          CI->addAttribute(AttributeList::FunctionIndex, Attribute::ReadOnly);
+          Fn->addFnAttr(Attribute::InaccessibleMemOnly);
+          CI->addAttribute(AttributeList::FunctionIndex,
+                           Attribute::InaccessibleMemOnly);
         }
         if ((Fn->getName() == "cblas_ddot" || Fn->getName() == "cblas_sdot") &&
             Fn->isDeclaration()) {

enzyme/Enzyme/EnzymeLogic.cpp

@@ -195,20 +195,6 @@ struct CacheAnalysis {
       // Pointer operands originating from call instructions that are not
       // malloc/free are conservatively considered uncacheable.
       if (auto obj_op = dyn_cast<CallInst>(obj)) {
-        Function *called = obj_op->getCalledFunction();
-#if LLVM_VERSION_MAJOR >= 11
-        if (auto castinst = dyn_cast<ConstantExpr>(obj_op->getCalledOperand()))
-#else
-        if (auto castinst = dyn_cast<ConstantExpr>(obj_op->getCalledValue()))
-#endif
-        {
-          if (castinst->isCast()) {
-            if (auto fn = dyn_cast<Function>(castinst->getOperand(0))) {
-              called = fn;
-            }
-          }
-        }
-
         // If this is a known allocation which is not captured or returned,
         // a caller function cannot overwrite this (since it cannot access).
         // Since we don't currently perform this check, we can instead check