1 //===- lib/MC/MCWinEH.cpp - Windows EH implementation ---------------------===//
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/ADT/StringRef.h"
11 #include "llvm/MC/MCContext.h"
12 #include "llvm/MC/MCObjectFileInfo.h"
13 #include "llvm/MC/MCSectionCOFF.h"
14 #include "llvm/MC/MCStreamer.h"
15 #include "llvm/MC/MCSymbol.h"
16 #include "llvm/MC/MCWinEH.h"
17 #include "llvm/Support/COFF.h"
18
19 namespace llvm {
20 namespace WinEH {
21
22 /// We can't have one section for all .pdata or .xdata because the Microsoft
23 /// linker seems to want all code relocations to refer to the same object file
24 /// section. If the code described is comdat, create a new comdat section
25 /// associated with that comdat. If the code described is not in the main .text
26 /// section, make a new section for it. Otherwise use the main unwind info
27 /// section.
getUnwindInfoSection(StringRef SecName,const MCSectionCOFF * UnwindSec,const MCSymbol * Function,MCContext & Context)28 static const MCSection *getUnwindInfoSection(
29 StringRef SecName, const MCSectionCOFF *UnwindSec, const MCSymbol *Function,
30 MCContext &Context) {
31 if (Function && Function->isInSection()) {
32 // If Function is in a COMDAT, get or create an unwind info section in that
33 // COMDAT group.
34 const MCSectionCOFF *FunctionSection =
35 cast<MCSectionCOFF>(&Function->getSection());
36 if (FunctionSection->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
37 return Context.getAssociativeCOFFSection(
38 UnwindSec, FunctionSection->getCOMDATSymbol());
39 }
40
41 // If Function is in a section other than .text, create a new .pdata section.
42 // Otherwise use the plain .pdata section.
43 if (const auto *Section = dyn_cast<MCSectionCOFF>(FunctionSection)) {
44 StringRef CodeSecName = Section->getSectionName();
45 if (CodeSecName == ".text")
46 return UnwindSec;
47
48 if (CodeSecName.startswith(".text$"))
49 CodeSecName = CodeSecName.substr(6);
50
51 return Context.getCOFFSection(
52 (SecName + Twine('$') + CodeSecName).str(),
53 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
54 SectionKind::getDataRel());
55 }
56 }
57
58 return UnwindSec;
59
60 }
61
getPDataSection(const MCSymbol * Function,MCContext & Context)62 const MCSection *UnwindEmitter::getPDataSection(const MCSymbol *Function,
63 MCContext &Context) {
64 const MCSectionCOFF *PData =
65 cast<MCSectionCOFF>(Context.getObjectFileInfo()->getPDataSection());
66 return getUnwindInfoSection(".pdata", PData, Function, Context);
67 }
68
getXDataSection(const MCSymbol * Function,MCContext & Context)69 const MCSection *UnwindEmitter::getXDataSection(const MCSymbol *Function,
70 MCContext &Context) {
71 const MCSectionCOFF *XData =
72 cast<MCSectionCOFF>(Context.getObjectFileInfo()->getXDataSection());
73 return getUnwindInfoSection(".xdata", XData, Function, Context);
74 }
75
76 }
77 }
78
79