Home | History | Annotate | Download | only in MC 
      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::setSelection(int Selection,
     32                                  const MCSectionCOFF *Assoc) const {
     33   assert(Selection != 0 && "invalid COMDAT selection type");
     34   assert((Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) ==
     35          (Assoc != 0) &&
     36     "associative COMDAT section must have an associated section");
     37   this->Selection = Selection;
     38   this->Assoc = Assoc;
     39   Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
     40 }
     41 
     42 void MCSectionCOFF::PrintSwitchToSection(const MCAsmInfo &MAI,
     43                                          raw_ostream &OS,
     44                                          const MCExpr *Subsection) const {
     45 
     46   // standard sections don't require the '.section'
     47   if (ShouldOmitSectionDirective(SectionName, MAI)) {
     48     OS << '\t' << getSectionName() << '\n';
     49     return;
     50   }
     51 
     52   OS << "\t.section\t" << getSectionName() << ",\"";
     53   if (getKind().isText())
     54     OS << 'x';
     55   if (getKind().isWriteable())
     56     OS << 'w';
     57   else
     58     OS << 'r';
     59   if (getCharacteristics() & COFF::IMAGE_SCN_MEM_DISCARDABLE)
     60     OS << 'n';
     61   OS << "\"\n";
     62 
     63   if (getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
     64     switch (Selection) {
     65       case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES:
     66         OS << "\t.linkonce one_only\n";
     67         break;
     68       case COFF::IMAGE_COMDAT_SELECT_ANY:
     69         OS << "\t.linkonce discard\n";
     70         break;
     71       case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE:
     72         OS << "\t.linkonce same_size\n";
     73         break;
     74       case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
     75         OS << "\t.linkonce same_contents\n";
     76         break;
     77       case COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE:
     78         OS << "\t.linkonce associative " << Assoc->getSectionName() << "\n";
     79         break;
     80       case COFF::IMAGE_COMDAT_SELECT_LARGEST:
     81         OS << "\t.linkonce largest\n";
     82         break;
     83       case COFF::IMAGE_COMDAT_SELECT_NEWEST:
     84         OS << "\t.linkonce newest\n";
     85         break;
     86       default:
     87         assert (0 && "unsupported COFF selection type");
     88         break;
     89     }
     90   }
     91 }
     92 
     93 bool MCSectionCOFF::UseCodeAlign() const {
     94   return getKind().isText();
     95 }
     96 
     97 bool MCSectionCOFF::isVirtualSection() const {
     98   return getCharacteristics() & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
     99 }
    100