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/Support/Format.h"
12 #include "llvm/Support/raw_ostream.h"
13 namespace llvm {
14 class MCExpr;
15 class Triple;
16 } // namespace llvm
17 
18 using namespace llvm;
19 
20 MCSectionXCOFF::~MCSectionXCOFF() = default;
21 
22 void MCSectionXCOFF::printCsectDirective(raw_ostream &OS) const {
23   OS << "\t.csect " << QualName->getName() << "," << Log2(getAlign()) << '\n';
24 }
25 
26 void MCSectionXCOFF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
27                                           raw_ostream &OS,
28                                           const MCExpr *Subsection) const {
29   if (getKind().isText()) {
30     if (getMappingClass() != XCOFF::XMC_PR)
31       report_fatal_error("Unhandled storage-mapping class for .text csect");
32 
33     printCsectDirective(OS);
34     return;
35   }
36 
37   if (getKind().isReadOnly()) {
38     if (getMappingClass() != XCOFF::XMC_RO &&
39         getMappingClass() != XCOFF::XMC_TD)
40       report_fatal_error("Unhandled storage-mapping class for .rodata csect.");
41     printCsectDirective(OS);
42     return;
43   }
44 
45   if (getKind().isReadOnlyWithRel()) {
46     if (getMappingClass() != XCOFF::XMC_RW &&
47         getMappingClass() != XCOFF::XMC_RO &&
48         getMappingClass() != XCOFF::XMC_TD)
49       report_fatal_error(
50           "Unexepected storage-mapping class for ReadOnlyWithRel kind");
51     printCsectDirective(OS);
52     return;
53   }
54 
55   // Initialized TLS data.
56   if (getKind().isThreadData()) {
57     // We only expect XMC_TL here for initialized TLS data.
58     if (getMappingClass() != XCOFF::XMC_TL)
59       report_fatal_error("Unhandled storage-mapping class for .tdata csect.");
60     printCsectDirective(OS);
61     return;
62   }
63 
64   if (getKind().isData()) {
65     switch (getMappingClass()) {
66     case XCOFF::XMC_RW:
67     case XCOFF::XMC_DS:
68     case XCOFF::XMC_TD:
69       printCsectDirective(OS);
70       break;
71     case XCOFF::XMC_TC:
72     case XCOFF::XMC_TE:
73       break;
74     case XCOFF::XMC_TC0:
75       OS << "\t.toc\n";
76       break;
77     default:
78       report_fatal_error(
79           "Unhandled storage-mapping class for .data csect.");
80     }
81     return;
82   }
83 
84   if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
85     assert((getKind().isBSSExtern() || getKind().isBSSLocal()) &&
86            "Unexepected section kind for toc-data");
87     printCsectDirective(OS);
88     return;
89   }
90   // Common csect type (uninitialized storage) does not have to print csect
91   // directive for section switching.
92   if (isCsect() && getCSectType() == XCOFF::XTY_CM) {
93     assert((getMappingClass() == XCOFF::XMC_RW ||
94             getMappingClass() == XCOFF::XMC_BS ||
95             getMappingClass() == XCOFF::XMC_UL) &&
96            "Generated a storage-mapping class for a common/bss/tbss csect we "
97            "don't "
98            "understand how to switch to.");
99     // Common symbols and local zero-initialized symbols for TLS and Non-TLS are
100     // eligible for .bss/.tbss csect, getKind().isThreadBSS() is used to cover
101     // TLS common and zero-initialized local symbols since linkage type (in the
102     // GlobalVariable) is not accessible in this class.
103     assert((getKind().isBSSLocal() || getKind().isCommon() ||
104             getKind().isThreadBSS()) &&
105            "wrong symbol type for .bss/.tbss csect");
106     // Don't have to print a directive for switching to section for commons and
107     // zero-initialized TLS data. The '.comm' and '.lcomm' directives of the
108     // variable will create the needed csect.
109     return;
110   }
111 
112   // Zero-initialized TLS data with weak or external linkage are not eligible to
113   // be put into common csect.
114   if (getKind().isThreadBSS()) {
115     printCsectDirective(OS);
116     return;
117   }
118 
119   // XCOFF debug sections.
120   if (getKind().isMetadata() && isDwarfSect()) {
121     OS << "\n\t.dwsect " << format("0x%" PRIx32, *getDwarfSubtypeFlags())
122        << '\n';
123     OS << MAI.getPrivateLabelPrefix() << getName() << ':' << '\n';
124     return;
125   }
126 
127   report_fatal_error("Printing for this SectionKind is unimplemented.");
128 }
129 
130 bool MCSectionXCOFF::useCodeAlign() const { return getKind().isText(); }
131 
132 bool MCSectionXCOFF::isVirtualSection() const {
133   // DWARF sections are always not virtual.
134   if (isDwarfSect())
135     return false;
136   assert(isCsect() &&
137          "Handling for isVirtualSection not implemented for this section!");
138   return XCOFF::XTY_CM == CsectProp->Type;
139 }
140