LLVM数据流分析的理论
标量优化（scalar目录）： 死代码消除（BDCE.cpp[code]，ADCE.cpp[code]，DCE.cpp[code]）, 全局值编号（GVN.cpp[code]）, 代码提升（ConstantHoisting.cpp[code]）， 公共子表达式消除（EarlyCSE.cpp[code]）， 代码下沉(Sink.cpp[code]), 以及各种循环优化等
过程间优化（IPO目录）：无效参数消除(DeadArgumentElimination.cpp[code]) , 全局死代码消除(GlobalDCE.cpp[code]), 常量传播（IPConstantPropagation.cpp[code]）， 循环外提（LoopExtractor.cpp[code]），稀疏条件常量传播（SCCP.cpp[code]）,函数合并（MergeFunctions.cpp[code]）等
介绍
本文档描述了构成 LLVM的内部软件，不是 LLVM 的外部使用。这里没有关于如何使用 LLVM 的说明，只有构成软件的 API。有关使用说明，请参阅程序员指南或参考手册。
警告
本文档直接从带有 doxygen 的源代码生成。由于 LLVM 一直在积极开发中，可能仍然有用，因为 LLVM 的某些部分非常稳定。
Transforms Directory Reference
AggressiveInstCombine.cpp File Reference
#include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
#include "AggressiveInstCombineInternal.h"
#include "llvm-c/Initialization.h"
#include "llvm-c/Transforms/AggressiveInstCombine.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Transforms/Utils/Local.h"
AggressiveInstCombineInternal.h File Reference
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/KnownBits.h"
Include dependency graph for AggressiveInstCombineInternal.h:
CFGuard Directory Reference
Directory dependency graph for CFGuard:
CFGuard.cpp File Reference
#include "llvm/Transforms/CFGuard.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/Triple.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
Include dependency graph for CFGuard.cpp:
/home/buildbot/as-worker-4/publish-doxygen-docs/llvm-project/llvm/include/llvm/ADT/ilist_node.h
侵入式列表节点。用于启用侵入式列表成员资格的基类，包括simple_ilist、iplist和ilist。第一个模板参数是列表的value_type。
可以使用编译时，选项配置 ilist 节点，更改行为和/或添加 API。
默认情况下，当且仅当 LLVM_ENABLE_ABI_BREAKING_CHECKS 时，ilist_node 才知道是否是列表监测（ilist_sentinel的实例）。函数isKnownSentinel()总是返回false跟踪关闭。Sentinel 跟踪从“prev”链接中窃取了一点，在递减迭代器时，添加了掩码操作，但在ilist_iterator 中启用了错误查找断言。
要始终打开监测跟踪，请传入 ilist_sentinel_tracking<true> 模板参数。这也启用了isSentinel()函数。必须将相同的选项传递给侵入式列表。（ ilist_sentinel_tracking<false> 始终关闭监测跟踪。）
通过传入不同的ilist_tag选项，一个类型可以多次从 ilist_node 继承。这允许将单个实例同时插入到多个列表中，其中每个列表都被赋予相同的标签。
struct A {}; struct B {}; struct N : ilist_node<N, ilist_tag>, ilist_node<N, ilist_tag> {};
void foo() { simple_ilist<N, ilist_tag> ListA; simple_ilist<N, ilist_tag> ListB; N N1; ListA.push_back(N1); ListB.push_back(N1); } endexample
See is_valid_option for steps on adding a new option.
//===- llvm/ADT/ilist_node.h - Intrusive Linked List Helper -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the ilist_node class template, which is a convenient
// base class for creating classes that can be used with ilists.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_ILIST_NODE_H
#define LLVM_ADT_ILIST_NODE_H
#include "llvm/ADT/ilist_node_base.h"
#include "llvm/ADT/ilist_node_options.h"
namespace llvm {
namespace ilist_detail {
struct NodeAccess;
} // end namespace ilist_detail
template <class OptionsT, bool IsReverse, bool IsConst> class ilist_iterator;
template <class OptionsT> class ilist_sentinel;
/// Implementation for an ilist node.
///
/// Templated on an appropriate a ilist_detail::node_options, usually computed
/// by a ilist_detail::compute_node_options.
///
/// This is a wrapper around a ilist_node_base whose main purpose is to
/// provide type safety: you can't insert nodes of a ilist_node_impl into the
/// wrong a simple_ilist or a iplist.
template <class OptionsT> class ilist_node_impl : OptionsT::node_base_type {
using value_type = typename OptionsT::value_type;
using node_base_type = typename OptionsT::node_base_type;
using list_base_type = typename OptionsT::list_base_type;
friend typename OptionsT::list_base_type;
friend struct ilist_detail::NodeAccess;
friend class ilist_sentinel<OptionsT>;
friend class ilist_iterator<OptionsT, false, false>;
friend class ilist_iterator<OptionsT, false, true>;
friend class ilist_iterator<OptionsT, true, false>;
friend class ilist_iterator<OptionsT, true, true>;
protected:
using self_iterator = ilist_iterator<OptionsT, false, false>;
using const_self_iterator = ilist_iterator<OptionsT, false, true>;
using reverse_self_iterator = ilist_iterator<OptionsT, true, false>;
using const_reverse_self_iterator = ilist_iterator<OptionsT, true, true>;
ilist_node_impl() = default;
private:
ilist_node_impl *getPrev() {
return static_cast<ilist_node_impl *>(node_base_type::getPrev());
}
ilist_node_impl *getNext() {
return static_cast<ilist_node_impl *>(node_base_type::getNext());
}
const ilist_node_impl *getPrev() const {
return static_cast<ilist_node_impl *>(node_base_type::getPrev());
}
const ilist_node_impl *getNext() const {
return static_cast<ilist_node_impl *>(node_base_type::getNext());
}
void setPrev(ilist_node_impl *N) { node_base_type::setPrev(N); }
void setNext(ilist_node_impl *N) { node_base_type::setNext(N); }
public:
self_iterator getIterator() { return self_iterator(*this); }
const_self_iterator getIterator() const { return const_self_iterator(*this); }
reverse_self_iterator getReverseIterator() {
return reverse_self_iterator(*this);
}
const_reverse_self_iterator getReverseIterator() const {
return const_reverse_self_iterator(*this);
}
// Under-approximation, but always available for assertions.
using node_base_type::isKnownSentinel;
/// Check whether this is the sentinel node.
///
/// This requires sentinel tracking to be explicitly enabled. Use the
/// ilist_sentinel_tracking<true> option to get this API.
bool isSentinel() const {
static_assert(OptionsT::is_sentinel_tracking_explicit,
"Use ilist_sentinel_tracking<true> to enable isSentinel()");
return node_base_type::isSentinel();
}
};
/// An intrusive list node.
///
/// A base class to enable membership in intrusive lists, including a
/// simple_ilist, a iplist, and a ilist. The first template parameter is the
/// a value_type for the list.
///
/// An ilist node can be configured with compile-time options to change
/// behaviour and/or add API.
///
/// By default, an a ilist_node knows whether it is the list sentinel (an
/// instance of a ilist_sentinel) if and only if
/// LLVM_ENABLE_ABI_BREAKING_CHECKS. The function a isKnownSentinel() always
/// returns c false tracking is off. Sentinel tracking steals a bit from the
/// "prev" link, which adds a mask operation when decrementing an iterator, but
/// enables bug-finding assertions in a ilist_iterator.
///
/// To turn sentinel tracking on all the time, pass in the
/// ilist_sentinel_tracking<true> template parameter. This also enables the a
/// isSentinel() function. The same option must be passed to the intrusive
/// list. (ilist_sentinel_tracking<false> turns sentinel tracking off all the
/// time.)
///
/// A type can inherit from ilist_node multiple times by passing in different
/// a ilist_tag options. This allows a single instance to be inserted into
/// multiple lists simultaneously, where each list is given the same tag.
///
/// example
/// struct A {};
/// struct B {};
/// struct N : ilist_node<N, ilist_tag<A>>, ilist_node<N, ilist_tag<B>> {};
///
/// void foo() {
/// simple_ilist<N, ilist_tag<A>> ListA;
/// simple_ilist<N, ilist_tag<B>> ListB;
/// N N1;
/// ListA.push_back(N1);
/// ListB.push_back(N1);
/// }
/// endexample
///
/// See a is_valid_option for steps on adding a new option.
template <class T, class... Options>
class ilist_node
: public ilist_node_impl<
typename ilist_detail::compute_node_options<T, Options...>::type> {
static_assert(ilist_detail::check_options<Options...>::value,
"Unrecognized node option!");
};
namespace ilist_detail {
/// An access class for ilist_node private API.
///
/// This gives access to the private parts of ilist nodes. Nodes for an ilist
/// should friend this class if they inherit privately from ilist_node.
///
/// Using this class outside of the ilist implementation is unsupported.
struct NodeAccess {
protected:
template <class OptionsT>
static ilist_node_impl<OptionsT> *getNodePtr(typename OptionsT::pointer N) {
return N;
}
template <class OptionsT>
static const ilist_node_impl<OptionsT> *
getNodePtr(typename OptionsT::const_pointer N) {
return N;
}
template <class OptionsT>
static typename OptionsT::pointer getValuePtr(ilist_node_impl<OptionsT> *N) {
return static_cast<typename OptionsT::pointer>(N);
}
template <class OptionsT>
static typename OptionsT::const_pointer
getValuePtr(const ilist_node_impl<OptionsT> *N) {
return static_cast<typename OptionsT::const_pointer>(N);
}
template <class OptionsT>
static ilist_node_impl<OptionsT> *getPrev(ilist_node_impl<OptionsT> &N) {
return N.getPrev();
}
template <class OptionsT>
static ilist_node_impl<OptionsT> *getNext(ilist_node_impl<OptionsT> &N) {
return N.getNext();
}
template <class OptionsT>
static const ilist_node_impl<OptionsT> *
getPrev(const ilist_node_impl<OptionsT> &N) {
return N.getPrev();
}
template <class OptionsT>
static const ilist_node_impl<OptionsT> *
getNext(const ilist_node_impl<OptionsT> &N) {
return N.getNext();
}
};
template <class OptionsT> struct SpecificNodeAccess : NodeAccess {
protected:
using pointer = typename OptionsT::pointer;
using const_pointer = typename OptionsT::const_pointer;
using node_type = ilist_node_impl<OptionsT>;
static node_type *getNodePtr(pointer N) {
return NodeAccess::getNodePtr<OptionsT>(N);
}
static const node_type *getNodePtr(const_pointer N) {
return NodeAccess::getNodePtr<OptionsT>(N);
}
static pointer getValuePtr(node_type *N) {
return NodeAccess::getValuePtr<OptionsT>(N);
}
static const_pointer getValuePtr(const node_type *N) {
return NodeAccess::getValuePtr<OptionsT>(N);
}
};
} // end namespace ilist_detail
template <class OptionsT>
class ilist_sentinel : public ilist_node_impl<OptionsT> {
public:
ilist_sentinel() {
this->initializeSentinel();
reset();
}
void reset() {
this->setPrev(this);
this->setNext(this);
}
bool empty() const { return this == this->getPrev(); }
};
/// An ilist node that can access its parent list.
///
/// Requires c NodeTy to have a getParent() to find the parent node, and the
/// c ParentTy to have a getSublistAccess() to get a reference to the list.
template <typename NodeTy, typename ParentTy, class... Options>
class ilist_node_with_parent : public ilist_node<NodeTy, Options...> {
protected:
ilist_node_with_parent() = default;
private:
/// Forward to NodeTy::getParent().
///
/// Note: do not use the name "getParent()". We want a compile error
/// (instead of recursion) when the subclass fails to implement a
/// getParent().
const ParentTy *getNodeParent() const {
return static_cast<const NodeTy *>(this)->getParent();
}
public:
/// @name Adjacent Node Accessors
/// @{
/// Get the previous node, or c nullptr for the list head.
NodeTy *getPrevNode() {
// Should be separated to a reused function, but then we couldn't use auto
// (and would need the type of the list).
const auto &List =
getNodeParent()->*(ParentTy::getSublistAccess((NodeTy *)nullptr));
return List.getPrevNode(*static_cast<NodeTy *>(this));
}
/// Get the previous node, or c nullptr for the list head.
const NodeTy *getPrevNode() const {
return const_cast<ilist_node_with_parent *>(this)->getPrevNode();
}
/// Get the next node, or c nullptr for the list tail.
NodeTy *getNextNode() {
// Should be separated to a reused function, but then we couldn't use auto
// (and would need the type of the list).
const auto &List =
getNodeParent()->*(ParentTy::getSublistAccess((NodeTy *)nullptr));
return List.getNextNode(*static_cast<NodeTy *>(this));
}
/// Get the next node, or c nullptr for the list tail.
const NodeTy *getNextNode() const {
return const_cast<ilist_node_with_parent *>(this)->getNextNode();
}
/// @}
};
} // end namespace llvm
#endif // LLVM_ADT_ILIST_NODE_H
参考链接：
https://www.zhihu.com/question/41123019
https://llvm.org/doxygen/index.html