#define DEBUG_TYPE "elfce"
+#include "ELF.h"
+#include "ELFWriter.h"
#include "ELFCodeEmitter.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
+#include "llvm/CodeGen/BinaryObject.h"
#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/CodeGen/MachineRelocation.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetELFWriterInfo.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
//===----------------------------------------------------------------------===//
// ELFCodeEmitter Implementation
/// startFunction - This callback is invoked when a new machine function is
/// about to be emitted.
void ELFCodeEmitter::startFunction(MachineFunction &MF) {
- const TargetData *TD = TM.getTargetData();
- const Function *F = MF.getFunction();
-
- // Align the output buffer to the appropriate alignment, power of 2.
- unsigned FnAlign = F->getAlignment();
- unsigned TDAlign = TD->getPrefTypeAlignment(F->getType());
- unsigned Align = std::max(FnAlign, TDAlign);
- assert(!(Align & (Align-1)) && "Alignment is not a power of two!");
+ DEBUG(dbgs() << "processing function: "
+ << MF.getFunction()->getName() << "\n");
// Get the ELF Section that this function belongs in.
- ES = &EW.getTextSection();
+ ES = &EW.getTextSection(MF.getFunction());
- // FIXME: better memory management, this will be replaced by BinaryObjects
- ES->SectionData.reserve(4096);
- BufferBegin = &ES->SectionData[0];
- BufferEnd = BufferBegin + ES->SectionData.capacity();
+ // Set the desired binary object to be used by the code emitters
+ setBinaryObject(ES);
- // Upgrade the section alignment if required.
- if (ES->Align < Align) ES->Align = Align;
+ // Get the function alignment in bytes
+ unsigned Align = (1 << MF.getAlignment());
- // Round the size up to the correct alignment for starting the new function.
- ES->Size = (ES->Size + (Align-1)) & (-Align);
+ // The function must start on its required alignment
+ ES->emitAlignment(Align);
- // Snaity check on allocated space for text section
- assert( ES->Size < 4096 && "no more space in TextSection" );
+ // Update the section alignment if needed.
+ ES->Align = std::max(ES->Align, Align);
- // FIXME: Using ES->Size directly here instead of calculating it from the
- // output buffer size (impossible because the code emitter deals only in raw
- // bytes) forces us to manually synchronize size and write padding zero bytes
- // to the output buffer for all non-text sections. For text sections, we do
- // not synchonize the output buffer, and we just blow up if anyone tries to
- // write non-code to it. An assert should probably be added to
- // AddSymbolToSection to prevent calling it on the text section.
- CurBufferPtr = BufferBegin + ES->Size;
+ // Record the function start offset
+ FnStartOff = ES->getCurrentPCOffset();
- // Record function start address relative to BufferBegin
- FnStartPtr = CurBufferPtr;
+ // Emit constant pool and jump tables to their appropriate sections.
+ // They need to be emitted before the function because in some targets
+ // the later may reference JT or CP entry address.
+ emitConstantPool(MF.getConstantPool());
+ if (MF.getJumpTableInfo())
+ emitJumpTables(MF.getJumpTableInfo());
}
/// finishFunction - This callback is invoked after the function is completely
/// finished.
bool ELFCodeEmitter::finishFunction(MachineFunction &MF) {
// Add a symbol to represent the function.
- ELFSym FnSym(MF.getFunction());
-
- // Figure out the binding (linkage) of the symbol.
- switch (MF.getFunction()->getLinkage()) {
- default:
- // appending linkage is illegal for functions.
- assert(0 && "Unknown linkage type!");
- case GlobalValue::ExternalLinkage:
- FnSym.SetBind(ELFSym::STB_GLOBAL);
- break;
- case GlobalValue::LinkOnceAnyLinkage:
- case GlobalValue::LinkOnceODRLinkage:
- case GlobalValue::WeakAnyLinkage:
- case GlobalValue::WeakODRLinkage:
- FnSym.SetBind(ELFSym::STB_WEAK);
- break;
- case GlobalValue::PrivateLinkage:
- assert (0 && "PrivateLinkage should not be in the symbol table.");
- case GlobalValue::InternalLinkage:
- FnSym.SetBind(ELFSym::STB_LOCAL);
- break;
+ const Function *F = MF.getFunction();
+ ELFSym *FnSym = ELFSym::getGV(F, EW.getGlobalELFBinding(F), ELFSym::STT_FUNC,
+ EW.getGlobalELFVisibility(F));
+ FnSym->SectionIdx = ES->SectionIdx;
+ FnSym->Size = ES->getCurrentPCOffset()-FnStartOff;
+ EW.AddPendingGlobalSymbol(F, true);
+
+ // Offset from start of Section
+ FnSym->Value = FnStartOff;
+
+ if (!F->hasPrivateLinkage())
+ EW.SymbolList.push_back(FnSym);
+
+ // Patch up Jump Table Section relocations to use the real MBBs offsets
+ // now that the MBB label offsets inside the function are known.
+ if (MF.getJumpTableInfo()) {
+ ELFSection &JTSection = EW.getJumpTableSection();
+ for (std::vector<MachineRelocation>::iterator MRI = JTRelocations.begin(),
+ MRE = JTRelocations.end(); MRI != MRE; ++MRI) {
+ MachineRelocation &MR = *MRI;
+ uintptr_t MBBOffset = getMachineBasicBlockAddress(MR.getBasicBlock());
+ MR.setResultPointer((void*)MBBOffset);
+ MR.setConstantVal(ES->SectionIdx);
+ JTSection.addRelocation(MR);
+ }
}
- // Set the symbol type as a function
- FnSym.SetType(ELFSym::STT_FUNC);
+ // If we have emitted any relocations to function-specific objects such as
+ // basic blocks, constant pools entries, or jump tables, record their
+ // addresses now so that we can rewrite them with the correct addresses later
+ for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
+ MachineRelocation &MR = Relocations[i];
+ intptr_t Addr;
+ if (MR.isGlobalValue()) {
+ EW.AddPendingGlobalSymbol(MR.getGlobalValue());
+ } else if (MR.isExternalSymbol()) {
+ EW.AddPendingExternalSymbol(MR.getExternalSymbol());
+ } else if (MR.isBasicBlock()) {
+ Addr = getMachineBasicBlockAddress(MR.getBasicBlock());
+ MR.setConstantVal(ES->SectionIdx);
+ MR.setResultPointer((void*)Addr);
+ } else if (MR.isConstantPoolIndex()) {
+ Addr = getConstantPoolEntryAddress(MR.getConstantPoolIndex());
+ MR.setConstantVal(CPSections[MR.getConstantPoolIndex()]);
+ MR.setResultPointer((void*)Addr);
+ } else if (MR.isJumpTableIndex()) {
+ ELFSection &JTSection = EW.getJumpTableSection();
+ Addr = getJumpTableEntryAddress(MR.getJumpTableIndex());
+ MR.setConstantVal(JTSection.SectionIdx);
+ MR.setResultPointer((void*)Addr);
+ } else {
+ llvm_unreachable("Unhandled relocation type");
+ }
+ ES->addRelocation(MR);
+ }
- FnSym.SectionIdx = ES->SectionIdx;
- FnSym.Size = CurBufferPtr-FnStartPtr;
+ // Clear per-function data structures.
+ JTRelocations.clear();
+ Relocations.clear();
+ CPLocations.clear();
+ CPSections.clear();
+ JTLocations.clear();
+ MBBLocations.clear();
+ return false;
+}
- // Offset from start of Section
- FnSym.Value = FnStartPtr-BufferBegin;
+/// emitConstantPool - For each constant pool entry, figure out which section
+/// the constant should live in and emit the constant
+void ELFCodeEmitter::emitConstantPool(MachineConstantPool *MCP) {
+ const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
+ if (CP.empty()) return;
- // Finally, add it to the symtab.
- EW.SymbolTable.push_back(FnSym);
+ // TODO: handle PIC codegen
+ assert(TM.getRelocationModel() != Reloc::PIC_ &&
+ "PIC codegen not yet handled for elf constant pools!");
- // Update Section Size
- ES->Size = CurBufferPtr - BufferBegin;
- return false;
+ for (unsigned i = 0, e = CP.size(); i != e; ++i) {
+ MachineConstantPoolEntry CPE = CP[i];
+
+ // Record the constant pool location and the section index
+ ELFSection &CstPool = EW.getConstantPoolSection(CPE);
+ CPLocations.push_back(CstPool.size());
+ CPSections.push_back(CstPool.SectionIdx);
+
+ if (CPE.isMachineConstantPoolEntry())
+ assert("CPE.isMachineConstantPoolEntry not supported yet");
+
+ // Emit the constant to constant pool section
+ EW.EmitGlobalConstant(CPE.Val.ConstVal, CstPool);
+ }
+}
+
+/// emitJumpTables - Emit all the jump tables for a given jump table info
+/// record to the appropriate section.
+void ELFCodeEmitter::emitJumpTables(MachineJumpTableInfo *MJTI) {
+ const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
+ if (JT.empty()) return;
+
+ // FIXME: handle PIC codegen
+ assert(TM.getRelocationModel() != Reloc::PIC_ &&
+ "PIC codegen not yet handled for elf jump tables!");
+
+ const TargetELFWriterInfo *TEW = TM.getELFWriterInfo();
+ unsigned EntrySize = 4; //MJTI->getEntrySize();
+
+ // Get the ELF Section to emit the jump table
+ ELFSection &JTSection = EW.getJumpTableSection();
+
+ // For each JT, record its offset from the start of the section
+ for (unsigned i = 0, e = JT.size(); i != e; ++i) {
+ const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
+
+ // Record JT 'i' offset in the JT section
+ JTLocations.push_back(JTSection.size());
+
+ // Each MBB entry in the Jump table section has a relocation entry
+ // against the current text section.
+ for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
+ unsigned MachineRelTy = TEW->getAbsoluteLabelMachineRelTy();
+ MachineRelocation MR =
+ MachineRelocation::getBB(JTSection.size(), MachineRelTy, MBBs[mi]);
+
+ // Add the relocation to the Jump Table section
+ JTRelocations.push_back(MR);
+
+ // Output placeholder for MBB in the JT section
+ for (unsigned s=0; s < EntrySize; ++s)
+ JTSection.emitByte(0);
+ }
+ }
}
} // end namespace llvm
projects / oota-llvm.git / blobdiff