[LLVM] Update apis incompatible with llvm versions in codegen (pytorch#110200)

Opaque pointers support is disabled in llvm 14 and enabled by default from llvm 15 and above.
setOpaquePointers api usage is deprecated from llvm 16. Removed this API.

Update CreateMalloc and CreateFree apis for latest llvm release.

Pull Request resolved: pytorch#110200
Approved by: https://github.com/Skylion007

Author: skc7

torch/csrc/jit/tensorexpr/llvm_codegen.cpp

@@ -491,9 +491,6 @@ LLVMCodeGenImpl::LLVMCodeGenImpl(
       irb_(getContext()),
       kernel_func_name_(std::move(kernel_func_name)),
       bufsExtAlloc_(ExternalAllocBufFinder::find(stmt)) {
-#if LLVM_VERSION_MAJOR >= 15
-  context_->setOpaquePointers(true);
-#endif
   if (!triple) {
     triple = LLVMTargetTriple();
   }
@@ -2573,14 +2570,18 @@ void LLVMCodeGenImpl::visit(AllocatePtr v) {
     }
   }
 
+#if LLVM_VERSION_MAJOR > 17
+  llvm::Instruction* I = irb_.CreateMalloc(
+      LongTy_, dtypeToLLVM(v->dtype()), size, nullptr, nullptr, "");
+#else
   llvm::Instruction* I = llvm::CallInst::CreateMalloc(
       irb_.GetInsertBlock(),
       LongTy_,
       dtypeToLLVM(v->dtype()),
       size,
       nullptr,
       nullptr);
-
+#endif
   // Insert the bitcast into the block.
   irb_.SetInsertPoint(irb_.GetInsertBlock());
   llvm::Value* malloc = irb_.Insert(I);
@@ -2607,7 +2608,11 @@ void LLVMCodeGenImpl::visit(FreePtr v) {
       : varToVal_.at(v->buffer_var());
 
   if (!llvm::isa<llvm::AllocaInst>(ptr)) {
+#if LLVM_VERSION_MAJOR > 17
+    irb_.Insert(irb_.CreateFree(ptr));
+#else
     irb_.Insert(llvm::CallInst::CreateFree(ptr, irb_.GetInsertBlock()));
+#endif
   }
 }