Add delete() function

src/codegen_llvm.cpp

@@ -146,6 +146,11 @@ void CodegenLLVM::visit(AssignMapCallStatement &assignment)
     b_.CreateStore(b_.CreateAdd(oldval, b_.getInt64(1)), newval);
     b_.CreateMapUpdateElem(map, key, newval);
   }
+  else if (call.func == "delete")
+  {
+    AllocaInst *key = getMapKey(map);
+    b_.CreateMapDeleteElem(map, key);
+  }
   else
   {
     abort();

src/irbuilderbpf.cpp

@@ -103,6 +103,25 @@ void IRBuilderBPF::CreateMapUpdateElem(Map &map, AllocaInst *key, Value *val)
   CallInst *call = CreateCall(update_func, {map_ptr, key, val, flags});
 }
 
+void IRBuilderBPF::CreateMapDeleteElem(Map &map, AllocaInst *key)
+{
+  Value *map_ptr = CreateBpfPseudoCall(map);
+  Value *flags = getInt64(0);
+
+  // int map_delete_elem(&map, &key)
+  // Return: 0 on success or negative error
+  FunctionType *delete_func_type = FunctionType::get(
+      getInt64Ty(),
+      {getInt8PtrTy(), getInt8PtrTy()},
+      false);
+  PointerType *delete_func_ptr_type = PointerType::get(delete_func_type, 0);
+  Constant *delete_func = ConstantExpr::getCast(
+      Instruction::IntToPtr,
+      getInt64(BPF_FUNC_map_delete_elem),
+      delete_func_ptr_type);
+  CallInst *call = CreateCall(delete_func, {map_ptr, key});
+}
+
 CallInst *IRBuilderBPF::CreateGetNs()
 {
   // u64 ktime_get_ns()

src/irbuilderbpf.h

@@ -21,6 +21,7 @@ public:
   CallInst   *CreateBpfPseudoCall(Map &map);
   LoadInst   *CreateMapLookupElem(Map &map, AllocaInst *key);
   void        CreateMapUpdateElem(Map &map, AllocaInst *key, Value *val);
+  void        CreateMapDeleteElem(Map &map, AllocaInst *key);
   CallInst   *CreateGetNs();
   CallInst   *CreateGetPidTgid();
   CallInst   *CreateGetUidGid();

src/semantic_analyser.cpp

@@ -51,6 +51,13 @@ void SemanticAnalyser::visit(Call &call)
       err_ << nargs << " provided)" << std::endl;
     }
   }
+  else if (call.func == "delete") {
+    // Don't assign a type
+    if (nargs != 0) {
+      err_ << "delete() should take 0 arguments (";
+      err_ << nargs << " provided)" << std::endl;
+    }
+  }
   else {
     type_ = Type::none;
     err_ << "Unknown function: '" << call.func << "'" << std::endl;