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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79763 91177308-0d34-0410-b5e6-96231b3b80d8
205 lines
7.3 KiB
C++
205 lines
7.3 KiB
C++
//===-- lib/CodeGen/ELFCodeEmitter.cpp ------------------------------------===//
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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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#define DEBUG_TYPE "elfce"
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#include "ELF.h"
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#include "ELFWriter.h"
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#include "ELFCodeEmitter.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Function.h"
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#include "llvm/CodeGen/BinaryObject.h"
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#include "llvm/CodeGen/MachineConstantPool.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineJumpTableInfo.h"
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#include "llvm/CodeGen/MachineRelocation.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetELFWriterInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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//===----------------------------------------------------------------------===//
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// ELFCodeEmitter Implementation
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//===----------------------------------------------------------------------===//
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namespace llvm {
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/// startFunction - This callback is invoked when a new machine function is
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/// about to be emitted.
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void ELFCodeEmitter::startFunction(MachineFunction &MF) {
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DEBUG(errs() << "processing function: "
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<< MF.getFunction()->getName() << "\n");
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// Get the ELF Section that this function belongs in.
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ES = &EW.getTextSection(MF.getFunction());
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// Set the desired binary object to be used by the code emitters
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setBinaryObject(ES);
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// Get the function alignment in bytes
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unsigned Align = (1 << MF.getAlignment());
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// The function must start on its required alignment
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ES->emitAlignment(Align);
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// Update the section alignment if needed.
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ES->Align = std::max(ES->Align, Align);
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// Record the function start offset
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FnStartOff = ES->getCurrentPCOffset();
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// Emit constant pool and jump tables to their appropriate sections.
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// They need to be emitted before the function because in some targets
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// the later may reference JT or CP entry address.
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emitConstantPool(MF.getConstantPool());
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emitJumpTables(MF.getJumpTableInfo());
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}
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/// finishFunction - This callback is invoked after the function is completely
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/// finished.
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bool ELFCodeEmitter::finishFunction(MachineFunction &MF) {
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// Add a symbol to represent the function.
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const Function *F = MF.getFunction();
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ELFSym *FnSym = ELFSym::getGV(F, EW.getGlobalELFBinding(F), ELFSym::STT_FUNC,
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EW.getGlobalELFVisibility(F));
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FnSym->SectionIdx = ES->SectionIdx;
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FnSym->Size = ES->getCurrentPCOffset()-FnStartOff;
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EW.AddPendingGlobalSymbol(F, true);
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// Offset from start of Section
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FnSym->Value = FnStartOff;
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if (!F->hasPrivateLinkage())
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EW.SymbolList.push_back(FnSym);
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// Patch up Jump Table Section relocations to use the real MBBs offsets
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// now that the MBB label offsets inside the function are known.
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if (!MF.getJumpTableInfo()->isEmpty()) {
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ELFSection &JTSection = EW.getJumpTableSection();
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for (std::vector<MachineRelocation>::iterator MRI = JTRelocations.begin(),
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MRE = JTRelocations.end(); MRI != MRE; ++MRI) {
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MachineRelocation &MR = *MRI;
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unsigned MBBOffset = getMachineBasicBlockAddress(MR.getBasicBlock());
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MR.setResultPointer((void*)MBBOffset);
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MR.setConstantVal(ES->SectionIdx);
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JTSection.addRelocation(MR);
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}
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}
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// If we have emitted any relocations to function-specific objects such as
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// basic blocks, constant pools entries, or jump tables, record their
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// addresses now so that we can rewrite them with the correct addresses later
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for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
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MachineRelocation &MR = Relocations[i];
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intptr_t Addr;
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if (MR.isGlobalValue()) {
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EW.AddPendingGlobalSymbol(MR.getGlobalValue());
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} else if (MR.isExternalSymbol()) {
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EW.AddPendingExternalSymbol(MR.getExternalSymbol());
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} else if (MR.isBasicBlock()) {
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Addr = getMachineBasicBlockAddress(MR.getBasicBlock());
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MR.setConstantVal(ES->SectionIdx);
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MR.setResultPointer((void*)Addr);
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} else if (MR.isConstantPoolIndex()) {
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Addr = getConstantPoolEntryAddress(MR.getConstantPoolIndex());
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MR.setConstantVal(CPSections[MR.getConstantPoolIndex()]);
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MR.setResultPointer((void*)Addr);
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} else if (MR.isJumpTableIndex()) {
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ELFSection &JTSection = EW.getJumpTableSection();
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Addr = getJumpTableEntryAddress(MR.getJumpTableIndex());
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MR.setConstantVal(JTSection.SectionIdx);
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MR.setResultPointer((void*)Addr);
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} else {
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llvm_unreachable("Unhandled relocation type");
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}
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ES->addRelocation(MR);
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}
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// Clear per-function data structures.
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JTRelocations.clear();
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Relocations.clear();
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CPLocations.clear();
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CPSections.clear();
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JTLocations.clear();
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MBBLocations.clear();
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return false;
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}
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/// emitConstantPool - For each constant pool entry, figure out which section
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/// the constant should live in and emit the constant
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void ELFCodeEmitter::emitConstantPool(MachineConstantPool *MCP) {
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const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
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if (CP.empty()) return;
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// TODO: handle PIC codegen
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assert(TM.getRelocationModel() != Reloc::PIC_ &&
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"PIC codegen not yet handled for elf constant pools!");
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for (unsigned i = 0, e = CP.size(); i != e; ++i) {
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MachineConstantPoolEntry CPE = CP[i];
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// Record the constant pool location and the section index
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ELFSection &CstPool = EW.getConstantPoolSection(CPE);
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CPLocations.push_back(CstPool.size());
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CPSections.push_back(CstPool.SectionIdx);
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if (CPE.isMachineConstantPoolEntry())
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assert("CPE.isMachineConstantPoolEntry not supported yet");
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// Emit the constant to constant pool section
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EW.EmitGlobalConstant(CPE.Val.ConstVal, CstPool);
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}
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}
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/// emitJumpTables - Emit all the jump tables for a given jump table info
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/// record to the appropriate section.
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void ELFCodeEmitter::emitJumpTables(MachineJumpTableInfo *MJTI) {
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const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
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if (JT.empty()) return;
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// FIXME: handle PIC codegen
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assert(TM.getRelocationModel() != Reloc::PIC_ &&
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"PIC codegen not yet handled for elf jump tables!");
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const TargetELFWriterInfo *TEW = TM.getELFWriterInfo();
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unsigned EntrySize = MJTI->getEntrySize();
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// Get the ELF Section to emit the jump table
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ELFSection &JTSection = EW.getJumpTableSection();
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// For each JT, record its offset from the start of the section
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for (unsigned i = 0, e = JT.size(); i != e; ++i) {
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const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
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// Record JT 'i' offset in the JT section
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JTLocations.push_back(JTSection.size());
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// Each MBB entry in the Jump table section has a relocation entry
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// against the current text section.
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for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
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unsigned MachineRelTy = TEW->getAbsoluteLabelMachineRelTy();
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MachineRelocation MR =
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MachineRelocation::getBB(JTSection.size(), MachineRelTy, MBBs[mi]);
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// Add the relocation to the Jump Table section
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JTRelocations.push_back(MR);
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// Output placeholder for MBB in the JT section
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for (unsigned s=0; s < EntrySize; ++s)
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JTSection.emitByte(0);
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}
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}
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}
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} // end namespace llvm
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