llvm/llvm/include/llvm/ExecutionEngine/JITLink/i386.h

//=== i386.h - Generic JITLink i386 edge kinds, utilities -*- 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
//
//===----------------------------------------------------------------------===//
//
// Generic utilities for graphs representing i386 objects.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_EXECUTIONENGINE_JITLINK_I386_H
#define LLVM_EXECUTIONENGINE_JITLINK_I386_H

#include "llvm/ExecutionEngine/JITLink/JITLink.h"
#include "llvm/ExecutionEngine/JITLink/TableManager.h"

namespace llvm::jitlink::i386 {
/// Represets i386 fixups
enum EdgeKind_i386 : Edge::Kind { … };

/// Returns a string name for the given i386 edge. For debugging purposes
/// only
const char *getEdgeKindName(Edge::Kind K);

/// Apply fixup expression for edge to block content.
inline Error applyFixup(LinkGraph &G, Block &B, const Edge &E,
                        const Symbol *GOTSymbol) { … }

/// i386 pointer size.
constexpr uint32_t PointerSize = …;

/// i386 null pointer content.
extern const char NullPointerContent[PointerSize];

/// i386 pointer jump stub content.
///
/// Contains the instruction sequence for an indirect jump via an in-memory
/// pointer:
///   jmpq *ptr
extern const char PointerJumpStubContent[6];

/// Creates a new pointer block in the given section and returns an anonymous
/// symbol pointing to it.
///
/// If InitialTarget is given then an Pointer32 relocation will be added to the
/// block pointing at InitialTarget.
///
/// The pointer block will have the following default values:
///   alignment: 32-bit
///   alignment-offset: 0
///   address: highest allowable (~7U)
inline Symbol &createAnonymousPointer(LinkGraph &G, Section &PointerSection,
                                      Symbol *InitialTarget = nullptr,
                                      uint64_t InitialAddend = 0) { … }

/// Create a jump stub block that jumps via the pointer at the given symbol.
///
/// The stub block will have the following default values:
///   alignment: 8-bit
///   alignment-offset: 0
///   address: highest allowable: (~5U)
inline Block &createPointerJumpStubBlock(LinkGraph &G, Section &StubSection,
                                         Symbol &PointerSymbol) { … }

/// Create a jump stub that jumps via the pointer at the given symbol and
/// an anonymous symbol pointing to it. Return the anonymous symbol.
///
/// The stub block will be created by createPointerJumpStubBlock.
inline Symbol &createAnonymousPointerJumpStub(LinkGraph &G,
                                              Section &StubSection,
                                              Symbol &PointerSymbol) { … }

/// Global Offset Table Builder.
class GOTTableManager : public TableManager<GOTTableManager> { … };

/// Procedure Linkage Table Builder.
class PLTTableManager : public TableManager<PLTTableManager> { … };

/// Optimize the GOT and Stub relocations if the edge target address is in range
/// 1. PCRel32GOTLoadRelaxable. For this edge kind, if the target is in range,
/// then replace GOT load with lea. (THIS IS UNIMPLEMENTED RIGHT NOW!)
/// 2. BranchPCRel32ToPtrJumpStubRelaxable. For this edge kind, if the target is
/// in range, replace a indirect jump by plt stub with a direct jump to the
/// target
Error optimizeGOTAndStubAccesses(LinkGraph &G);

} // namespace llvm::jitlink::i386

#endif // LLVM_EXECUTIONENGINE_JITLINK_I386_H