1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
//===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing DWARF exception info into asm files.
//
//===----------------------------------------------------------------------===//
#include "DwarfException.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
DwarfCFIExceptionBase::DwarfCFIExceptionBase(AsmPrinter *A)
: EHStreamer(A), shouldEmitCFI(false), hasEmittedCFISections(false) {}
void DwarfCFIExceptionBase::markFunctionEnd() {
endFragment();
// Map all labels and get rid of any dead landing pads.
if (!Asm->MF->getLandingPads().empty()) {
MachineFunction *NonConstMF = const_cast<MachineFunction*>(Asm->MF);
NonConstMF->tidyLandingPads();
}
}
void DwarfCFIExceptionBase::endFragment() {
if (shouldEmitCFI)
Asm->OutStreamer->EmitCFIEndProc();
}
DwarfCFIException::DwarfCFIException(AsmPrinter *A)
: DwarfCFIExceptionBase(A), shouldEmitPersonality(false),
forceEmitPersonality(false), shouldEmitLSDA(false),
shouldEmitMoves(false) {}
DwarfCFIException::~DwarfCFIException() {}
/// endModule - Emit all exception information that should come after the
/// content.
void DwarfCFIException::endModule() {
// SjLj uses this pass and it doesn't need this info.
if (!Asm->MAI->usesCFIForEH())
return;
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
if ((PerEncoding & 0x80) != dwarf::DW_EH_PE_indirect)
return;
// Emit references to all used personality functions
for (const Function *Personality : MMI->getPersonalities()) {
if (!Personality)
continue;
MCSymbol *Sym = Asm->getSymbol(Personality);
TLOF.emitPersonalityValue(*Asm->OutStreamer, Asm->getDataLayout(), Sym);
}
}
static MCSymbol *getExceptionSym(AsmPrinter *Asm) {
return Asm->getCurExceptionSym();
}
void DwarfCFIException::beginFunction(const MachineFunction *MF) {
shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
const Function &F = MF->getFunction();
// If any landing pads survive, we need an EH table.
bool hasLandingPads = !MF->getLandingPads().empty();
// See if we need frame move info.
AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
shouldEmitMoves = MoveType != AsmPrinter::CFI_M_None;
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
const Function *Per = nullptr;
if (F.hasPersonalityFn())
Per = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
// Emit a personality function even when there are no landing pads
forceEmitPersonality =
// ...if a personality function is explicitly specified
F.hasPersonalityFn() &&
// ... and it's not known to be a noop in the absence of invokes
!isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
// ... and we're not explicitly asked not to emit it
F.needsUnwindTableEntry();
shouldEmitPersonality =
(forceEmitPersonality ||
(hasLandingPads && PerEncoding != dwarf::DW_EH_PE_omit)) &&
Per;
unsigned LSDAEncoding = TLOF.getLSDAEncoding();
shouldEmitLSDA = shouldEmitPersonality &&
LSDAEncoding != dwarf::DW_EH_PE_omit;
shouldEmitCFI = MF->getMMI().getContext().getAsmInfo()->usesCFIForEH() &&
(shouldEmitPersonality || shouldEmitMoves);
beginFragment(&*MF->begin(), getExceptionSym);
}
void DwarfCFIException::beginFragment(const MachineBasicBlock *MBB,
ExceptionSymbolProvider ESP) {
if (!shouldEmitCFI)
return;
if (!hasEmittedCFISections) {
if (Asm->needsOnlyDebugCFIMoves())
Asm->OutStreamer->EmitCFISections(false, true);
hasEmittedCFISections = true;
}
Asm->OutStreamer->EmitCFIStartProc(/*IsSimple=*/false);
// Indicate personality routine, if any.
if (!shouldEmitPersonality)
return;
auto &F = MBB->getParent()->getFunction();
auto *P = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
assert(P && "Expected personality function");
// If we are forced to emit this personality, make sure to record
// it because it might not appear in any landingpad
if (forceEmitPersonality)
MMI->addPersonality(P);
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
unsigned PerEncoding = TLOF.getPersonalityEncoding();
const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(P, Asm->TM, MMI);
Asm->OutStreamer->EmitCFIPersonality(Sym, PerEncoding);
// Provide LSDA information.
if (shouldEmitLSDA)
Asm->OutStreamer->EmitCFILsda(ESP(Asm), TLOF.getLSDAEncoding());
}
/// endFunction - Gather and emit post-function exception information.
///
void DwarfCFIException::endFunction(const MachineFunction *MF) {
if (!shouldEmitPersonality)
return;
emitExceptionTable();
}
|
