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9b68e8653f
Emission for globals, using the correct data sections Function alignment can be computed for each target using TargetELFWriterInfo Some small fixes llvm-svn: 73201
132 lines
4.5 KiB
C++
132 lines
4.5 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 "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/MachineConstantPool.h"
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#include "llvm/CodeGen/MachineJumpTableInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Support/Debug.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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// Get the ELF Section that this function belongs in.
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ES = &EW.getTextSection();
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DOUT << "processing function: " << MF.getFunction()->getName() << "\n";
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// FIXME: better memory management, this will be replaced by BinaryObjects
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ES->SectionData.reserve(4096);
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BufferBegin = &ES->SectionData[0];
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BufferEnd = BufferBegin + ES->SectionData.capacity();
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// Align the output buffer with function alignment, and
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// upgrade the section alignment if required
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unsigned Align =
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TM.getELFWriterInfo()->getFunctionAlignment(MF.getFunction());
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if (ES->Align < Align) ES->Align = Align;
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ES->Size = (ES->Size + (Align-1)) & (-Align);
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// Snaity check on allocated space for text section
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assert( ES->Size < 4096 && "no more space in TextSection" );
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// FIXME: Using ES->Size directly here instead of calculating it from the
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// output buffer size (impossible because the code emitter deals only in raw
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// bytes) forces us to manually synchronize size and write padding zero bytes
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// to the output buffer for all non-text sections. For text sections, we do
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// not synchonize the output buffer, and we just blow up if anyone tries to
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// write non-code to it. An assert should probably be added to
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// AddSymbolToSection to prevent calling it on the text section.
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CurBufferPtr = BufferBegin + ES->Size;
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// Record function start address relative to BufferBegin
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FnStartPtr = CurBufferPtr;
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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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ELFSym FnSym(MF.getFunction());
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// Update Section Size
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ES->Size = CurBufferPtr - BufferBegin;
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// Figure out the binding (linkage) of the symbol.
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switch (MF.getFunction()->getLinkage()) {
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default:
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// appending linkage is illegal for functions.
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assert(0 && "Unknown linkage type!");
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case GlobalValue::ExternalLinkage:
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FnSym.SetBind(ELFSym::STB_GLOBAL);
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break;
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case GlobalValue::LinkOnceAnyLinkage:
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case GlobalValue::LinkOnceODRLinkage:
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case GlobalValue::WeakAnyLinkage:
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case GlobalValue::WeakODRLinkage:
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FnSym.SetBind(ELFSym::STB_WEAK);
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break;
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case GlobalValue::PrivateLinkage:
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assert (0 && "PrivateLinkage should not be in the symbol table.");
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case GlobalValue::InternalLinkage:
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FnSym.SetBind(ELFSym::STB_LOCAL);
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break;
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}
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// Set the symbol type as a function
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FnSym.SetType(ELFSym::STT_FUNC);
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FnSym.SectionIdx = ES->SectionIdx;
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FnSym.Size = CurBufferPtr-FnStartPtr;
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// Offset from start of Section
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FnSym.Value = FnStartPtr-BufferBegin;
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// Finally, add it to the symtab.
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EW.SymbolTable.push_back(FnSym);
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// Relocations
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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
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// 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.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.isGlobalValue()) {
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EW.PendingGlobals.insert(MR.getGlobalValue());
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} else {
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assert(0 && "Unhandled relocation type");
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}
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ES->Relocations.push_back(MR);
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}
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Relocations.clear();
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return false;
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}
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} // end namespace llvm
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