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2d274412ed
MachineRelocations, "stub" always refers to a far-call stub or a
load-a-faraway-global stub, so this patch adds "Far" to the term. (Other stubs
are used for lazy compilation and dlsym address replacement.) The variable was
also inconsistent between the positive and negative sense, and the positive
sense ("NeedStub") was more demanding than is accurate (since a nearby-enough
function can be called directly even if the platform often requires a stub).
Since the negative sense causes double-negatives, I switched to
"MayNeedFarStub" globally.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86363 91177308-0d34-0410-b5e6-96231b3b80d8
342 lines
12 KiB
C++
342 lines
12 KiB
C++
//===-- llvm/CodeGen/MachineRelocation.h - Target Relocation ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the MachineRelocation class.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_MACHINERELOCATION_H
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#define LLVM_CODEGEN_MACHINERELOCATION_H
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#include "llvm/System/DataTypes.h"
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#include <cassert>
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namespace llvm {
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class GlobalValue;
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class MachineBasicBlock;
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/// MachineRelocation - This represents a target-specific relocation value,
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/// produced by the code emitter. This relocation is resolved after the has
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/// been emitted, either to an object file or to memory, when the target of the
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/// relocation can be resolved.
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///
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/// A relocation is made up of the following logical portions:
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/// 1. An offset in the machine code buffer, the location to modify.
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/// 2. A target specific relocation type (a number from 0 to 63).
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/// 3. A symbol being referenced, either as a GlobalValue* or as a string.
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/// 4. An optional constant value to be added to the reference.
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/// 5. A bit, CanRewrite, which indicates to the JIT that a function stub is
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/// not needed for the relocation.
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/// 6. An index into the GOT, if the target uses a GOT
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///
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class MachineRelocation {
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enum AddressType {
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isResult, // Relocation has be transformed into its result pointer.
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isGV, // The Target.GV field is valid.
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isIndirectSym, // Relocation of an indirect symbol.
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isBB, // Relocation of BB address.
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isExtSym, // The Target.ExtSym field is valid.
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isConstPool, // Relocation of constant pool address.
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isJumpTable, // Relocation of jump table address.
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isGOTIndex // The Target.GOTIndex field is valid.
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};
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/// Offset - This is the offset from the start of the code buffer of the
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/// relocation to perform.
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uintptr_t Offset;
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/// ConstantVal - A field that may be used by the target relocation type.
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intptr_t ConstantVal;
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union {
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void *Result; // If this has been resolved to a resolved pointer
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GlobalValue *GV; // If this is a pointer to a GV or an indirect ref.
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MachineBasicBlock *MBB; // If this is a pointer to a LLVM BB
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const char *ExtSym; // If this is a pointer to a named symbol
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unsigned Index; // Constant pool / jump table index
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unsigned GOTIndex; // Index in the GOT of this symbol/global
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} Target;
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unsigned TargetReloType : 6; // The target relocation ID
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AddressType AddrType : 4; // The field of Target to use
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bool MayNeedFarStub : 1; // True if this relocation may require a far-stub
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bool GOTRelative : 1; // Should this relocation be relative to the GOT?
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bool TargetResolve : 1; // True if target should resolve the address
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public:
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// Relocation types used in a generic implementation. Currently, relocation
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// entries for all things use the generic VANILLA type until they are refined
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// into target relocation types.
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enum RelocationType {
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VANILLA
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};
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/// MachineRelocation::getGV - Return a relocation entry for a GlobalValue.
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///
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static MachineRelocation getGV(uintptr_t offset, unsigned RelocationType,
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GlobalValue *GV, intptr_t cst = 0,
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bool MayNeedFarStub = 0,
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bool GOTrelative = 0) {
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assert((RelocationType & ~63) == 0 && "Relocation type too large!");
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MachineRelocation Result;
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Result.Offset = offset;
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Result.ConstantVal = cst;
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Result.TargetReloType = RelocationType;
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Result.AddrType = isGV;
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Result.MayNeedFarStub = MayNeedFarStub;
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Result.GOTRelative = GOTrelative;
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Result.TargetResolve = false;
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Result.Target.GV = GV;
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return Result;
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}
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/// MachineRelocation::getIndirectSymbol - Return a relocation entry for an
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/// indirect symbol.
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static MachineRelocation getIndirectSymbol(uintptr_t offset,
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unsigned RelocationType,
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GlobalValue *GV, intptr_t cst = 0,
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bool MayNeedFarStub = 0,
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bool GOTrelative = 0) {
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assert((RelocationType & ~63) == 0 && "Relocation type too large!");
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MachineRelocation Result;
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Result.Offset = offset;
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Result.ConstantVal = cst;
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Result.TargetReloType = RelocationType;
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Result.AddrType = isIndirectSym;
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Result.MayNeedFarStub = MayNeedFarStub;
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Result.GOTRelative = GOTrelative;
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Result.TargetResolve = false;
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Result.Target.GV = GV;
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return Result;
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}
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/// MachineRelocation::getBB - Return a relocation entry for a BB.
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///
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static MachineRelocation getBB(uintptr_t offset,unsigned RelocationType,
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MachineBasicBlock *MBB, intptr_t cst = 0) {
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assert((RelocationType & ~63) == 0 && "Relocation type too large!");
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MachineRelocation Result;
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Result.Offset = offset;
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Result.ConstantVal = cst;
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Result.TargetReloType = RelocationType;
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Result.AddrType = isBB;
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Result.MayNeedFarStub = false;
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Result.GOTRelative = false;
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Result.TargetResolve = false;
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Result.Target.MBB = MBB;
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return Result;
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}
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/// MachineRelocation::getExtSym - Return a relocation entry for an external
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/// symbol, like "free".
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///
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static MachineRelocation getExtSym(uintptr_t offset, unsigned RelocationType,
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const char *ES, intptr_t cst = 0,
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bool GOTrelative = 0) {
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assert((RelocationType & ~63) == 0 && "Relocation type too large!");
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MachineRelocation Result;
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Result.Offset = offset;
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Result.ConstantVal = cst;
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Result.TargetReloType = RelocationType;
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Result.AddrType = isExtSym;
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Result.MayNeedFarStub = true;
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Result.GOTRelative = GOTrelative;
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Result.TargetResolve = false;
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Result.Target.ExtSym = ES;
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return Result;
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}
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/// MachineRelocation::getConstPool - Return a relocation entry for a constant
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/// pool entry.
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///
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static MachineRelocation getConstPool(uintptr_t offset,unsigned RelocationType,
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unsigned CPI, intptr_t cst = 0,
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bool letTargetResolve = false) {
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assert((RelocationType & ~63) == 0 && "Relocation type too large!");
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MachineRelocation Result;
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Result.Offset = offset;
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Result.ConstantVal = cst;
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Result.TargetReloType = RelocationType;
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Result.AddrType = isConstPool;
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Result.MayNeedFarStub = false;
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Result.GOTRelative = false;
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Result.TargetResolve = letTargetResolve;
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Result.Target.Index = CPI;
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return Result;
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}
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/// MachineRelocation::getJumpTable - Return a relocation entry for a jump
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/// table entry.
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///
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static MachineRelocation getJumpTable(uintptr_t offset,unsigned RelocationType,
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unsigned JTI, intptr_t cst = 0,
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bool letTargetResolve = false) {
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assert((RelocationType & ~63) == 0 && "Relocation type too large!");
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MachineRelocation Result;
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Result.Offset = offset;
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Result.ConstantVal = cst;
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Result.TargetReloType = RelocationType;
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Result.AddrType = isJumpTable;
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Result.MayNeedFarStub = false;
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Result.GOTRelative = false;
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Result.TargetResolve = letTargetResolve;
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Result.Target.Index = JTI;
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return Result;
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}
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/// getMachineCodeOffset - Return the offset into the code buffer that the
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/// relocation should be performed.
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intptr_t getMachineCodeOffset() const {
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return Offset;
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}
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/// getRelocationType - Return the target-specific relocation ID for this
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/// relocation.
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unsigned getRelocationType() const {
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return TargetReloType;
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}
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/// getConstantVal - Get the constant value associated with this relocation.
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/// This is often an offset from the symbol.
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///
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intptr_t getConstantVal() const {
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return ConstantVal;
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}
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/// setConstantVal - Set the constant value associated with this relocation.
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/// This is often an offset from the symbol.
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///
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void setConstantVal(intptr_t val) {
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ConstantVal = val;
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}
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/// isGlobalValue - Return true if this relocation is a GlobalValue, as
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/// opposed to a constant string.
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bool isGlobalValue() const {
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return AddrType == isGV;
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}
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/// isIndirectSymbol - Return true if this relocation is the address an
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/// indirect symbol
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bool isIndirectSymbol() const {
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return AddrType == isIndirectSym;
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}
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/// isBasicBlock - Return true if this relocation is a basic block reference.
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///
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bool isBasicBlock() const {
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return AddrType == isBB;
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}
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/// isExternalSymbol - Return true if this is a constant string.
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///
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bool isExternalSymbol() const {
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return AddrType == isExtSym;
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}
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/// isConstantPoolIndex - Return true if this is a constant pool reference.
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///
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bool isConstantPoolIndex() const {
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return AddrType == isConstPool;
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}
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/// isJumpTableIndex - Return true if this is a jump table reference.
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///
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bool isJumpTableIndex() const {
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return AddrType == isJumpTable;
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}
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/// isGOTRelative - Return true the target wants the index into the GOT of
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/// the symbol rather than the address of the symbol.
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bool isGOTRelative() const {
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return GOTRelative;
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}
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/// mayNeedFarStub - This function returns true if the JIT for this target may
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/// need either a stub function or an indirect global-variable load to handle
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/// the relocated GlobalValue reference. For example, the x86-64 call
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/// instruction can only call functions within +/-2GB of the call site.
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/// Anything farther away needs a longer mov+call sequence, which can't just
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/// be written on top of the existing call.
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bool mayNeedFarStub() const {
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return MayNeedFarStub;
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}
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/// letTargetResolve - Return true if the target JITInfo is usually
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/// responsible for resolving the address of this relocation.
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bool letTargetResolve() const {
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return TargetResolve;
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}
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/// getGlobalValue - If this is a global value reference, return the
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/// referenced global.
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GlobalValue *getGlobalValue() const {
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assert((isGlobalValue() || isIndirectSymbol()) &&
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"This is not a global value reference!");
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return Target.GV;
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}
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MachineBasicBlock *getBasicBlock() const {
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assert(isBasicBlock() && "This is not a basic block reference!");
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return Target.MBB;
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}
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/// getString - If this is a string value, return the string reference.
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///
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const char *getExternalSymbol() const {
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assert(isExternalSymbol() && "This is not an external symbol reference!");
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return Target.ExtSym;
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}
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/// getConstantPoolIndex - If this is a const pool reference, return
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/// the index into the constant pool.
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unsigned getConstantPoolIndex() const {
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assert(isConstantPoolIndex() && "This is not a constant pool reference!");
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return Target.Index;
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}
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/// getJumpTableIndex - If this is a jump table reference, return
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/// the index into the jump table.
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unsigned getJumpTableIndex() const {
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assert(isJumpTableIndex() && "This is not a jump table reference!");
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return Target.Index;
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}
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/// getResultPointer - Once this has been resolved to point to an actual
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/// address, this returns the pointer.
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void *getResultPointer() const {
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assert(AddrType == isResult && "Result pointer isn't set yet!");
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return Target.Result;
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}
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/// setResultPointer - Set the result to the specified pointer value.
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///
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void setResultPointer(void *Ptr) {
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Target.Result = Ptr;
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AddrType = isResult;
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}
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/// setGOTIndex - Set the GOT index to a specific value.
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void setGOTIndex(unsigned idx) {
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AddrType = isGOTIndex;
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Target.GOTIndex = idx;
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}
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/// getGOTIndex - Once this has been resolved to an entry in the GOT,
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/// this returns that index. The index is from the lowest address entry
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/// in the GOT.
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unsigned getGOTIndex() const {
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assert(AddrType == isGOTIndex);
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return Target.GOTIndex;
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}
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};
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}
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#endif
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