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      1 //===- lib/MC/MCSectionCOFF.cpp - COFF Code Section Representation --------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "llvm/MC/MCSectionCOFF.h"
     11 #include "llvm/MC/MCAsmInfo.h"
     12 #include "llvm/MC/MCContext.h"
     13 #include "llvm/MC/MCSymbol.h"
     14 #include "llvm/Support/raw_ostream.h"
     15 using namespace llvm;
     16 
     17 MCSectionCOFF::~MCSectionCOFF() {} // anchor.
     18 
     19 // ShouldOmitSectionDirective - Decides whether a '.section' directive
     20 // should be printed before the section name
     21 bool MCSectionCOFF::ShouldOmitSectionDirective(StringRef Name,
     22                                                const MCAsmInfo &MAI) const {
     23 
     24   // FIXME: Does .section .bss/.data/.text work everywhere??
     25   if (Name == ".text" || Name == ".data" || Name == ".bss")
     26     return true;
     27 
     28   return false;
     29 }
     30 
     31 void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
     32                                          raw_ostream &OS) const {
     33 
     34   // standard sections don't require the '.section'
     35   if (ShouldOmitSectionDirective(SectionName, MAI)) {
     36     OS << '\t' << getSectionName() << '\n';
     37     return;
     38   }
     39 
     40   OS << "\t.section\t" << getSectionName() << ",\"";
     41   if (getKind().isText())
     42     OS << 'x';
     43   if (getKind().isWriteable())
     44     OS << 'w';
     45   else
     46     OS << 'r';
     47   if (getCharacteristics() & COFF::IMAGE_SCN_MEM_DISCARDABLE)
     48     OS << 'n';
     49   OS << "\"\n";
     50 
     51   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
     52     switch (Selection) {
     53       case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
     54         OS << "\t.linkonce one_only\n";
     55         break;
     56       case COFF::IMAGE_COMDAT_SELECT_ANY:
     57         OS << "\t.linkonce discard\n";
     58         break;
     59       case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
     60         OS << "\t.linkonce same_size\n";
     61         break;
     62       case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
     63         OS << "\t.linkonce same_contents\n";
     64         break;
     65     //NOTE: as of binutils 2.20, there is no way to specifiy select largest
     66     //      with the .linkonce directive. For now, we treat it as an invalid
     67     //      comdat selection value.
     68       case COFF::IMAGE_COMDAT_SELECT_LARGEST:
     69     //  OS << "\t.linkonce largest\n";
     70     //  break;
     71       default:
     72         assert (0 && "unsupported COFF selection type");
     73         break;
     74     }
     75   }
     76 }
     77 
     78 bool MCSectionCOFF::UseCodeAlign() const {
     79   return getKind().isText();
     80 }
     81 
     82 bool MCSectionCOFF::isVirtualSection() const {
     83   return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
     84 }
     85