be/src/common/compiler_util.h

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#pragma once

// Compiler hint that this branch is likely or unlikely to
// be taken. Take from the "What all programmers should know
// about memory" paper.
// example: if (LIKELY(size > 0)) { ... }
// example: if (UNLIKELY(!status.ok())) { ... }
#define CACHE_LINE_SIZE 64

#ifdef LIKELY
#undef LIKELY
#endif

#ifdef UNLIKELY
#undef UNLIKELY
#endif

#define LIKELY(expr) __builtin_expect(!!(expr), 1)
#define UNLIKELY(expr) __builtin_expect(!!(expr), 0)

#define PREFETCH(addr) __builtin_prefetch(addr)

/// Force inlining. The 'inline' keyword is treated by most compilers as a hint,
/// not a command. This should be used sparingly for cases when either the function
/// needs to be inlined for a specific reason or the compiler's heuristics make a bad
/// decision, e.g. not inlining a small function on a hot path.
#ifdef ALWAYS_INLINE
#undef ALWAYS_INLINE
#endif
#define ALWAYS_INLINE __attribute__((always_inline))
#define NO_INLINE __attribute__((__noinline__))
#define MAY_ALIAS __attribute__((__may_alias__))

#define ALIGN_CACHE_LINE __attribute__((aligned(CACHE_LINE_SIZE)))

#ifdef __clang__
#define NO_SANITIZE_UNDEFINED __attribute__((__no_sanitize__("undefined")))
#else
#define NO_SANITIZE_UNDEFINED
#endif

// Allow reassociation only when the evaluation order is not part of the operation's contract.
// This may change the least significant bits of floating-point results.
#ifdef __clang__
#define ALLOW_FP_REASSOCIATION _Pragma("clang fp reassociate(on)")
#else
#define ALLOW_FP_REASSOCIATION
#endif