LLVM: lib/CodeGen/AsmPrinter/DwarfCFIException.cpp Source File

LLVM 22.0.0git
DwarfCFIException.cpp
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1//===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
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// This file contains support for writing DWARF exception info into asm files.
10//
11//===----------------------------------------------------------------------===//
12
13#include "DwarfException.h"
14#include "llvm/BinaryFormat/Dwarf.h"
15#include "llvm/CodeGen/AsmPrinter.h"
16#include "llvm/CodeGen/MachineFunction.h"
17#include "llvm/CodeGen/MachineModuleInfo.h"
18#include "llvm/IR/Function.h"
19#include "llvm/MC/MCAsmInfo.h"
20#include "llvm/MC/MCContext.h"
21#include "llvm/MC/MCStreamer.h"
22#include "llvm/Target/TargetLoweringObjectFile.h"
23#include "llvm/Target/TargetMachine.h"
24#include "llvm/Target/TargetOptions.h"
25using namespace llvm;
26
27 DwarfCFIException::DwarfCFIException(AsmPrinter *A) : EHStreamer(A) {}
28
29DwarfCFIException::~DwarfCFIException() = default;
30
31void DwarfCFIException::addPersonality(const GlobalValue *Personality) {
32 if (!llvm::is_contained(Personalities, Personality))
33 Personalities.push_back(Personality);
34}
35
36/// endModule - Emit all exception information that should come after the
37/// content.
39 // SjLj uses this pass and it doesn't need this info.
40 if (!Asm->MAI->usesCFIForEH())
41 return;
42
43 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
44
45 unsigned PerEncoding = TLOF.getPersonalityEncoding();
46
47 if ((PerEncoding & 0x80) != dwarf::DW_EH_PE_indirect)
48 return;
49
50 // Emit indirect reference table for all used personality functions
51 for (const GlobalValue *Personality : Personalities) {
52 MCSymbol *Sym = Asm->getSymbol(Personality);
53 TLOF.emitPersonalityValue(*Asm->OutStreamer, Asm->getDataLayout(), Sym,
54 Asm->MMI);
55 }
56 Personalities.clear();
57}
58
60 shouldEmitPersonality = shouldEmitLSDA = false;
61 const Function &F = MF->getFunction();
62
63 // If any landing pads survive, we need an EH table.
64 bool hasLandingPads = !MF->getLandingPads().empty();
65
66 // See if we need frame move info.
67 bool shouldEmitMoves =
68 Asm->getFunctionCFISectionType(*MF) != AsmPrinter::CFISection::None;
69
70 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
71 unsigned PerEncoding = TLOF.getPersonalityEncoding();
72 const GlobalValue *Per = nullptr;
73 if (F.hasPersonalityFn())
74 Per = dyn_cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
75
76 // Emit a personality function even when there are no landing pads
77 forceEmitPersonality =
78 // ...if a personality function is explicitly specified
79 F.hasPersonalityFn() &&
80 // ... and it's not known to be a noop in the absence of invokes
82 // ... and we're not explicitly asked not to emit it
83 F.needsUnwindTableEntry();
84
85 shouldEmitPersonality =
86 (forceEmitPersonality ||
87 (hasLandingPads && PerEncoding != dwarf::DW_EH_PE_omit)) &&
88 Per;
89
90 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
91 shouldEmitLSDA = shouldEmitPersonality &&
92 LSDAEncoding != dwarf::DW_EH_PE_omit;
93
94 const MCAsmInfo &MAI = *MF->getContext().getAsmInfo();
96 shouldEmitCFI =
97 MAI.usesCFIForEH() && (shouldEmitPersonality || shouldEmitMoves);
98 else
99 shouldEmitCFI = Asm->usesCFIWithoutEH() && shouldEmitMoves;
100}
101
103 if (!shouldEmitCFI)
104 return;
105
106 if (!hasEmittedCFISections) {
107 AsmPrinter::CFISection CFISecType = Asm->getModuleCFISectionType();
108 // If we don't say anything it implies `.cfi_sections .eh_frame`, so we
109 // chose not to be verbose in that case. And with `ForceDwarfFrameSection`,
110 // we should always emit .debug_frame.
111 if (CFISecType == AsmPrinter::CFISection::Debug ||
112 Asm->TM.Options.ForceDwarfFrameSection ||
113 Asm->TM.Options.MCOptions.EmitSFrameUnwind)
114 Asm->OutStreamer->emitCFISections(
115 CFISecType == AsmPrinter::CFISection::EH, true,
116 Asm->TM.Options.MCOptions.EmitSFrameUnwind);
117 hasEmittedCFISections = true;
118 }
119
120 Asm->OutStreamer->emitCFIStartProc(/*IsSimple=*/false);
121
122 // Indicate personality routine, if any.
123 if (!shouldEmitPersonality)
124 return;
125
126 auto &F = MBB.getParent()->getFunction();
127 auto *P = dyn_cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
128 assert(P && "Expected personality function");
129 // Record the personality function.
130 addPersonality(P);
131
132 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
133 unsigned PerEncoding = TLOF.getPersonalityEncoding();
134 const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(P, Asm->TM, MMI);
135 Asm->OutStreamer->emitCFIPersonality(Sym, PerEncoding);
136
137 // Provide LSDA information.
138 if (shouldEmitLSDA)
139 Asm->OutStreamer->emitCFILsda(Asm->getMBBExceptionSym(MBB),
140 TLOF.getLSDAEncoding());
141}
142
144 if (shouldEmitCFI)
145 Asm->OutStreamer->emitCFIEndProc();
146}
147
148/// endFunction - Gather and emit post-function exception information.
149///
151 if (!shouldEmitPersonality)
152 return;
153
155}
assert(UImm &&(UImm !=~static_cast< T >(0)) &&"Invalid immediate!")
MachineBasicBlock & MBB
A
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
This file contains constants used for implementing Dwarf debug support.
F
#define F(x, y, z)
Definition MD5.cpp:55
P
#define P(N)
This class is intended to be used as a driving class for all asm writers.
Definition AsmPrinter.h:96
@ EH
Emit .eh_frame.
Definition AsmPrinter.h:176
@ None
Do not emit either .eh_frame or .debug_frame.
Definition AsmPrinter.h:175
@ Debug
Emit .debug_frame.
Definition AsmPrinter.h:177
void endBasicBlockSection(const MachineBasicBlock &MBB) override
Process the end of a basic-block-section within a function.
~DwarfCFIException() override
void beginBasicBlockSection(const MachineBasicBlock &MBB) override
Process the beginning of a new basic-block-section within a function.
void endFunction(const MachineFunction *) override
Gather and emit post-function exception information.
void endModule() override
Emit all exception information that should come after the content.
DwarfCFIException(AsmPrinter *A)
void beginFunction(const MachineFunction *MF) override
Gather pre-function exception information.
AsmPrinter * Asm
Target of directive emission.
Definition EHStreamer.h:33
MCSymbol * emitExceptionTable()
Emit landing pads and actions.
Definition EHStreamer.cpp:379
MachineModuleInfo * MMI
Collected machine module information.
Definition EHStreamer.h:36
EHStreamer(AsmPrinter *A)
Definition EHStreamer.cpp:36
This class is intended to be used as a base class for asm properties and features specific to the tar...
Definition MCAsmInfo.h:64
bool usesCFIForEH() const
Returns true if the exception handling method for the platform uses call frame information to unwind.
Definition MCAsmInfo.h:646
ExceptionHandling getExceptionHandlingType() const
Definition MCAsmInfo.h:633
const MCAsmInfo * getAsmInfo() const
Definition MCContext.h:412
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition MCSymbol.h:42
MCContext & getContext() const
Function & getFunction()
Return the LLVM function that this machine code represents.
const std::vector< LandingPadInfo > & getLandingPads() const
Return a reference to the landing pad info for the current function.
virtual MCSymbol * getCFIPersonalitySymbol(const GlobalValue *GV, const TargetMachine &TM, MachineModuleInfo *MMI) const
virtual void emitPersonalityValue(MCStreamer &Streamer, const DataLayout &TM, const MCSymbol *Sym, const MachineModuleInfo *MMI) const
@ DW_EH_PE_indirect
Definition Dwarf.h:884
@ DW_EH_PE_omit
Definition Dwarf.h:869
This is an optimization pass for GlobalISel generic memory operations.
Definition AddressRanges.h:18
decltype(auto) dyn_cast(const From &Val)
dyn_cast<X> - Return the argument parameter cast to the specified type.
Definition Casting.h:643
@ None
No exception support.
Definition CodeGen.h:54
bool isNoOpWithoutInvoke(EHPersonality Pers)
Return true if this personality may be safely removed if there are no invoke instructions remaining i...
LLVM_ABI EHPersonality classifyEHPersonality(const Value *Pers)
See if the given exception handling personality function is one that we understand.
bool is_contained(R &&Range, const E &Element)
Returns true if Element is found in Range.
Definition STLExtras.h:1897
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