llvm-6502/lib/MC/MCNullStreamer.cpp
Eli Bendersky 030f63a397 Expose an InitToTextSection through MCStreamer.
The aim of this patch is to fix the following piece of code in the
platform-independent AsmParser:

void AsmParser::CheckForValidSection() {
  if (!ParsingInlineAsm && !getStreamer().getCurrentSection()) {
    TokError("expected section directive before assembly directive");
    Out.SwitchSection(Ctx.getMachOSection(
                        "__TEXT", "__text",
                        MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
                        0, SectionKind::getText()));
  }
}

This was added for the "-n" option of llvm-mc.

The proposed fix adds another virtual method to MCStreamer, called
InitToTextSection. Conceptually, it's similar to the existing
InitSections which initializes all common sections and switches to
text. The new method is implemented by each platform streamer in a way
that it sees fit. So AsmParser can now do this:

void AsmParser::CheckForValidSection() {
  if (!ParsingInlineAsm && !getStreamer().getCurrentSection()) {
    TokError("expected section directive before assembly directive");
    Out.InitToTextSection();
  }
}

Which is much more reasonable.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172450 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-14 19:04:57 +00:00

119 lines
4.5 KiB
C++

//===- lib/MC/MCNullStreamer.cpp - Dummy Streamer Implementation ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSymbol.h"
using namespace llvm;
namespace {
class MCNullStreamer : public MCStreamer {
public:
MCNullStreamer(MCContext &Context) : MCStreamer(Context) {}
/// @name MCStreamer Interface
/// @{
virtual void InitToTextSection() {
}
virtual void InitSections() {
}
virtual void ChangeSection(const MCSection *Section) {
}
virtual void EmitLabel(MCSymbol *Symbol) {
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
assert(getCurrentSection() && "Cannot emit before setting section!");
Symbol->setSection(*getCurrentSection());
}
virtual void EmitDebugLabel(MCSymbol *Symbol) {
EmitLabel(Symbol);
}
virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
virtual void EmitThumbFunc(MCSymbol *Func) {}
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {}
virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol){}
virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
const MCSymbol *LastLabel,
const MCSymbol *Label,
unsigned PointerSize) {}
virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute){}
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
virtual void EmitCOFFSymbolType(int Type) {}
virtual void EndCOFFSymbolDef() {}
virtual void EmitCOFFSecRel32(MCSymbol const *Symbol) {}
virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {}
virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {}
virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
uint64_t Size = 0, unsigned ByteAlignment = 0) {}
virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {}
virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}
virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {}
virtual void EmitULEB128Value(const MCExpr *Value) {}
virtual void EmitSLEB128Value(const MCExpr *Value) {}
virtual void EmitGPRel32Value(const MCExpr *Value) {}
virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
unsigned ValueSize = 1,
unsigned MaxBytesToEmit = 0) {}
virtual void EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit = 0) {}
virtual bool EmitValueToOffset(const MCExpr *Offset,
unsigned char Value = 0) { return false; }
virtual void EmitFileDirective(StringRef Filename) {}
virtual bool EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
StringRef Filename) {
return false;
}
virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
unsigned Column, unsigned Flags,
unsigned Isa, unsigned Discriminator,
StringRef FileName) {}
virtual void EmitInstruction(const MCInst &Inst) {}
virtual void EmitBundleAlignMode(unsigned AlignPow2) {}
virtual void EmitBundleLock(bool AlignToEnd) {}
virtual void EmitBundleUnlock() {}
virtual void FinishImpl() {}
virtual void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
RecordProcEnd(Frame);
}
/// @}
};
}
MCStreamer *llvm::createNullStreamer(MCContext &Context) {
return new MCNullStreamer(Context);
}