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This patch fixes an old FIXME by creating a MCTargetStreamer interface and moving the target specific functions for ARM, Mips and PPC to it. The ARM streamer is still declared in a common place because it is used from lib/CodeGen/ARMException.cpp, but the Mips and PPC are completely hidden in the corresponding Target directories. I will send an email to llvmdev with instructions on how to use this. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192181 91177308-0d34-0410-b5e6-96231b3b80d8
160 lines
5.2 KiB
C++
160 lines
5.2 KiB
C++
//===- lib/MC/AArch64ELFStreamer.cpp - ELF Object Output for AArch64 ------===//
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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 assembles .s files and emits AArch64 ELF .o object files. Different
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// from generic ELF streamer in emitting mapping symbols ($x and $d) to delimit
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// regions of data and code.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MC/MCELFStreamer.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCELF.h"
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#include "llvm/MC/MCELFStreamer.h"
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#include "llvm/MC/MCELFSymbolFlags.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCObjectStreamer.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ELF.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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/// Extend the generic ELFStreamer class so that it can emit mapping symbols at
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/// the appropriate points in the object files. These symbols are defined in the
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/// AArch64 ELF ABI:
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/// infocenter.arm.com/help/topic/com.arm.doc.ihi0056a/IHI0056A_aaelf64.pdf
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///
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/// In brief: $x or $d should be emitted at the start of each contiguous region
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/// of A64 code or data in a section. In practice, this emission does not rely
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/// on explicit assembler directives but on inherent properties of the
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/// directives doing the emission (e.g. ".byte" is data, "add x0, x0, x0" an
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/// instruction).
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///
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/// As a result this system is orthogonal to the DataRegion infrastructure used
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/// by MachO. Beware!
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class AArch64ELFStreamer : public MCELFStreamer {
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public:
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AArch64ELFStreamer(MCContext &Context, MCAsmBackend &TAB, raw_ostream &OS,
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MCCodeEmitter *Emitter)
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: MCELFStreamer(Context, 0, TAB, OS, Emitter), MappingSymbolCounter(0),
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LastEMS(EMS_None) {}
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~AArch64ELFStreamer() {}
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virtual void ChangeSection(const MCSection *Section,
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const MCExpr *Subsection) {
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// We have to keep track of the mapping symbol state of any sections we
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// use. Each one should start off as EMS_None, which is provided as the
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// default constructor by DenseMap::lookup.
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LastMappingSymbols[getPreviousSection().first] = LastEMS;
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LastEMS = LastMappingSymbols.lookup(Section);
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MCELFStreamer::ChangeSection(Section, Subsection);
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}
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/// This function is the one used to emit instruction data into the ELF
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/// streamer. We override it to add the appropriate mapping symbol if
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/// necessary.
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virtual void EmitInstruction(const MCInst& Inst) {
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EmitA64MappingSymbol();
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MCELFStreamer::EmitInstruction(Inst);
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}
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/// This is one of the functions used to emit data into an ELF section, so the
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/// AArch64 streamer overrides it to add the appropriate mapping symbol ($d)
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/// if necessary.
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virtual void EmitBytes(StringRef Data) {
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EmitDataMappingSymbol();
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MCELFStreamer::EmitBytes(Data);
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}
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/// This is one of the functions used to emit data into an ELF section, so the
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/// AArch64 streamer overrides it to add the appropriate mapping symbol ($d)
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/// if necessary.
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virtual void EmitValueImpl(const MCExpr *Value, unsigned Size) {
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EmitDataMappingSymbol();
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MCELFStreamer::EmitValueImpl(Value, Size);
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}
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private:
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enum ElfMappingSymbol {
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EMS_None,
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EMS_A64,
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EMS_Data
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};
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void EmitDataMappingSymbol() {
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if (LastEMS == EMS_Data) return;
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EmitMappingSymbol("$d");
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LastEMS = EMS_Data;
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}
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void EmitA64MappingSymbol() {
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if (LastEMS == EMS_A64) return;
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EmitMappingSymbol("$x");
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LastEMS = EMS_A64;
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}
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void EmitMappingSymbol(StringRef Name) {
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MCSymbol *Start = getContext().CreateTempSymbol();
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EmitLabel(Start);
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MCSymbol *Symbol =
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getContext().GetOrCreateSymbol(Name + "." +
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Twine(MappingSymbolCounter++));
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MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
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MCELF::SetType(SD, ELF::STT_NOTYPE);
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MCELF::SetBinding(SD, ELF::STB_LOCAL);
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SD.setExternal(false);
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AssignSection(Symbol, getCurrentSection().first);
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const MCExpr *Value = MCSymbolRefExpr::Create(Start, getContext());
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Symbol->setVariableValue(Value);
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}
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int64_t MappingSymbolCounter;
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DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
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ElfMappingSymbol LastEMS;
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/// @}
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};
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}
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namespace llvm {
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MCELFStreamer* createAArch64ELFStreamer(MCContext &Context, MCAsmBackend &TAB,
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raw_ostream &OS, MCCodeEmitter *Emitter,
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bool RelaxAll, bool NoExecStack) {
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AArch64ELFStreamer *S = new AArch64ELFStreamer(Context, TAB, OS, Emitter);
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if (RelaxAll)
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S->getAssembler().setRelaxAll(true);
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if (NoExecStack)
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S->getAssembler().setNoExecStack(true);
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return S;
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}
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}
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