llvm/lib/MC/MCSectionXCOFF.cpp

   1 //===- lib/MC/MCSectionXCOFF.cpp - XCOFF Code Section Representation ------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/MC/MCSectionXCOFF.h"
  10 #include "llvm/MC/MCAsmInfo.h"
  11 #include "llvm/MC/MCExpr.h"
  12 #include "llvm/Support/Debug.h"
  13 #include "llvm/Support/Format.h"
  14 #include "llvm/Support/raw_ostream.h"
  15
  16 using namespace llvm;
  17
  18 MCSectionXCOFF::~MCSectionXCOFF() = default;
  19
  20 void MCSectionXCOFF::printCsectDirective(raw_ostream &OS) const {
  21   OS << "\t.csect " << QualName->getName() << "," << Log2_32(getAlignment())
  22      << '\n';
  23 }
  24
  25 void MCSectionXCOFF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
  26                                           raw_ostream &OS,
  27                                           const MCExpr *Subsection) const {
  28   if (getKind().isText()) {
  29     if (getMappingClass() != XCOFF::XMC_PR)
  30       report_fatal_error("Unhandled storage-mapping class for .text csect");
  31
  32     printCsectDirective(OS);
  33     return;
  34   }
  35
  36   if (getKind().isReadOnly()) {
  37     if (getMappingClass() != XCOFF::XMC_RO)
  38       report_fatal_error("Unhandled storage-mapping class for .rodata csect.");
  39     printCsectDirective(OS);
  40     return;
  41   }
  42
  43   // Initialized TLS data.
  44   if (getKind().isThreadData()) {
  45     // We only expect XMC_TL here for initialized TLS data.
  46     if (getMappingClass() != XCOFF::XMC_TL)
  47       report_fatal_error("Unhandled storage-mapping class for .tdata csect.");
  48     printCsectDirective(OS);
  49     return;
  50   }
  51
  52   if (getKind().isData()) {
  53     switch (getMappingClass()) {
  54     case XCOFF::XMC_RW:
  55     case XCOFF::XMC_DS:
  56     case XCOFF::XMC_TD:
  57       printCsectDirective(OS);
  58       break;
  59     case XCOFF::XMC_TC:
  60     case XCOFF::XMC_TE:
  61       break;
  62     case XCOFF::XMC_TC0:
  63       OS << "\t.toc\n";
  64       break;
  65     default:
  66       report_fatal_error(
  67           "Unhandled storage-mapping class for .data csect.");
  68     }
  69     return;
  70   }
  71
  72   if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
  73     assert((getKind().isBSSExtern() || getKind().isBSSLocal()) &&
  74            "Unexepected section kind for toc-data");
  75     printCsectDirective(OS);
  76     return;
  77   }
  78   // Common csect type (uninitialized storage) does not have to print csect
  79   // directive for section switching.
  80   if (isCsect() && getCSectType() == XCOFF::XTY_CM) {
  81     assert((getMappingClass() == XCOFF::XMC_RW ||
  82             getMappingClass() == XCOFF::XMC_BS ||
  83             getMappingClass() == XCOFF::XMC_UL) &&
  84            "Generated a storage-mapping class for a common/bss/tbss csect we "
  85            "don't "
  86            "understand how to switch to.");
  87     // Common symbols and local zero-initialized symbols for TLS and Non-TLS are
  88     // eligible for .bss/.tbss csect, getKind().isThreadBSS() is used to cover
  89     // TLS common and zero-initialized local symbols since linkage type (in the
  90     // GlobalVariable) is not accessible in this class.
  91     assert((getKind().isBSSLocal() || getKind().isCommon() ||
  92             getKind().isThreadBSS()) &&
  93            "wrong symbol type for .bss/.tbss csect");
  94     // Don't have to print a directive for switching to section for commons and
  95     // zero-initialized TLS data. The '.comm' and '.lcomm' directives of the
  96     // variable will create the needed csect.
  97     return;
  98   }
  99
 100   // Zero-initialized TLS data with weak or external linkage are not eligible to
 101   // be put into common csect.
 102   if (getKind().isThreadBSS()) {
 103     printCsectDirective(OS);
 104     return;
 105   }
 106
 107   // XCOFF debug sections.
 108   if (getKind().isMetadata() && isDwarfSect()) {
 109     OS << "\n\t.dwsect "
 110        << format("0x%" PRIx32, getDwarfSubtypeFlags().getValue()) << '\n';
 111     OS << MAI.getPrivateLabelPrefix() << getName() << ':' << '\n';
 112     return;
 113   }
 114
 115   report_fatal_error("Printing for this SectionKind is unimplemented.");
 116 }
 117
 118 bool MCSectionXCOFF::UseCodeAlign() const { return getKind().isText(); }
 119
 120 bool MCSectionXCOFF::isVirtualSection() const {
 121   assert(isCsect() && "Only csect section can be virtual!");
 122   return XCOFF::XTY_CM == CsectProp->Type;
 123 }