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,MCSectionCOFF * UnwindSec,const MCSymbol * Function,MCContext & Context)28 static MCSection *getUnwindInfoSection(StringRef SecName,
29 MCSectionCOFF *UnwindSec,
30 const MCSymbol *Function,
31 MCContext &Context) {
32 if (Function && Function->isInSection()) {
33 // If Function is in a COMDAT, get or create an unwind info section in that
34 // COMDAT group.
35 const MCSectionCOFF *FunctionSection =
36 cast<MCSectionCOFF>(&Function->getSection());
37 if (FunctionSection->getCharacteristics() & COFF::IMAGE_SCN_LNK_COMDAT) {
38 return Context.getAssociativeCOFFSection(
39 UnwindSec, FunctionSection->getCOMDATSymbol());
40 }
41
42 // If Function is in a section other than .text, create a new .pdata section.
43 // Otherwise use the plain .pdata section.
44 if (const auto *Section = dyn_cast<MCSectionCOFF>(FunctionSection)) {
45 StringRef CodeSecName = Section->getSectionName();
46 if (CodeSecName == ".text")
47 return UnwindSec;
48
49 if (CodeSecName.startswith(".text$"))
50 CodeSecName = CodeSecName.substr(6);
51
52 return Context.getCOFFSection((SecName + Twine('$') + CodeSecName).str(),
53 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
54 COFF::IMAGE_SCN_MEM_READ,
55 SectionKind::getData());
56 }
57 }
58
59 return UnwindSec;
60
61 }
62
getPDataSection(const MCSymbol * Function,MCContext & Context)63 MCSection *UnwindEmitter::getPDataSection(const MCSymbol *Function,
64 MCContext &Context) {
65 MCSectionCOFF *PData =
66 cast<MCSectionCOFF>(Context.getObjectFileInfo()->getPDataSection());
67 return getUnwindInfoSection(".pdata", PData, Function, Context);
68 }
69
getXDataSection(const MCSymbol * Function,MCContext & Context)70 MCSection *UnwindEmitter::getXDataSection(const MCSymbol *Function,
71 MCContext &Context) {
72 MCSectionCOFF *XData =
73 cast<MCSectionCOFF>(Context.getObjectFileInfo()->getXDataSection());
74 return getUnwindInfoSection(".xdata", XData, Function, Context);
75 }
76
77 }
78 }
79
80