Add comm builtin

src/codegen_llvm.cpp

@@ -60,6 +60,12 @@ void CodegenLLVM::visit(Builtin &builtin)
       expr_ = b_.CreateLShr(uidgid, 32);
     }
   }
+  else if (builtin.ident == "comm")
+  {
+    AllocaInst *buf = b_.CreateAllocaBPF(builtin.type, "comm");
+    b_.CreateGetCurrentComm(buf, b_.getInt64(builtin.type.size));
+    expr_ = buf;
+  }
   else if (!builtin.ident.compare(0, 3, "arg") && builtin.ident.size() == 4 &&
       builtin.ident.at(3) >= '0' && builtin.ident.at(3) <= '9')
   {

src/irbuilderbpf.cpp

@@ -250,5 +250,21 @@ CallInst *IRBuilderBPF::CreateGetStackId(Value *ctx, bool ustack)
   return CreateCall(getstackid_func, {ctx, map_ptr, flags_val}, "get_stackid");
 }
 
+void IRBuilderBPF::CreateGetCurrentComm(AllocaInst *buf, Value *size)
+{
+  // int bpf_get_current_comm(char *buf, int size_of_buf)
+  // Return: 0 on success or negative error
+  FunctionType *getcomm_func_type = FunctionType::get(
+      getInt64Ty(),
+      {getInt8PtrTy(), getInt64Ty()},
+      false);
+  PointerType *getcomm_func_ptr_type = PointerType::get(getcomm_func_type, 0);
+  Constant *getcomm_func = ConstantExpr::getCast(
+      Instruction::IntToPtr,
+      getInt64(BPF_FUNC_get_current_comm),
+      getcomm_func_ptr_type);
+  CreateCall(getcomm_func, {buf, size}, "get_comm");
+}
+
 } // namespace ast
 } // namespace bpftrace

src/irbuilderbpf.h

@@ -31,6 +31,7 @@ public:
   CallInst   *CreateGetPidTgid();
   CallInst   *CreateGetUidGid();
   CallInst   *CreateGetStackId(Value *ctx, bool ustack);
+  void        CreateGetCurrentComm(AllocaInst *buf, Value *size);
 
 private:
   Module &module_;

src/semantic_analyser.cpp

@@ -39,6 +39,9 @@ void SemanticAnalyser::visit(Builtin &builtin)
     builtin.type = SizedType(Type::ustack, 8);
     needs_stackid_map_ = true;
   }
+  else if (builtin.ident == "comm") {
+    builtin.type = SizedType(Type::string, STRING_SIZE);
+  }
   else if (!builtin.ident.compare(0, 3, "arg") && builtin.ident.size() == 4 &&
       builtin.ident.at(3) >= '0' && builtin.ident.at(3) <= '9') {
     int arg_num = atoi(builtin.ident.substr(3).c_str());