Bug Summary

File:lib/MC/MCWinCOFFStreamer.cpp
Warning:line 274, column 1
Potential leak of memory pointed to by 'Fragment'

Annotated Source Code

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1//===- llvm/MC/MCWinCOFFStreamer.cpp --------------------------------------===//
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// This file contains an implementation of a Windows COFF object file streamer.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/ADT/SmallString.h"
15#include "llvm/ADT/SmallVector.h"
16#include "llvm/ADT/Triple.h"
17#include "llvm/ADT/Twine.h"
18#include "llvm/BinaryFormat/COFF.h"
19#include "llvm/MC/MCAsmBackend.h"
20#include "llvm/MC/MCAssembler.h"
21#include "llvm/MC/MCCodeEmitter.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCFixup.h"
25#include "llvm/MC/MCFragment.h"
26#include "llvm/MC/MCObjectFileInfo.h"
27#include "llvm/MC/MCObjectStreamer.h"
28#include "llvm/MC/MCSection.h"
29#include "llvm/MC/MCSymbolCOFF.h"
30#include "llvm/MC/MCWinCOFFStreamer.h"
31#include "llvm/Support/Casting.h"
32#include "llvm/Support/ErrorHandling.h"
33#include "llvm/Support/MathExtras.h"
34#include "llvm/Support/SMLoc.h"
35#include "llvm/Support/raw_ostream.h"
36#include <algorithm>
37#include <cassert>
38#include <cstdint>
39
40using namespace llvm;
41
42#define DEBUG_TYPE"WinCOFFStreamer" "WinCOFFStreamer"
43
44MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context,
45 std::unique_ptr<MCAsmBackend> MAB,
46 std::unique_ptr<MCCodeEmitter> CE,
47 raw_pwrite_stream &OS)
48 : MCObjectStreamer(Context, std::move(MAB), OS, std::move(CE)),
49 CurSymbol(nullptr) {}
50
51void MCWinCOFFStreamer::EmitInstToData(const MCInst &Inst,
52 const MCSubtargetInfo &STI) {
53 MCDataFragment *DF = getOrCreateDataFragment();
54
55 SmallVector<MCFixup, 4> Fixups;
56 SmallString<256> Code;
57 raw_svector_ostream VecOS(Code);
58 getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
59
60 // Add the fixups and data.
61 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
62 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
63 DF->getFixups().push_back(Fixups[i]);
64 }
65
66 DF->getContents().append(Code.begin(), Code.end());
67}
68
69void MCWinCOFFStreamer::InitSections(bool NoExecStack) {
70 // FIXME: this is identical to the ELF one.
71 // This emulates the same behavior of GNU as. This makes it easier
72 // to compare the output as the major sections are in the same order.
73 SwitchSection(getContext().getObjectFileInfo()->getTextSection());
74 EmitCodeAlignment(4);
75
76 SwitchSection(getContext().getObjectFileInfo()->getDataSection());
77 EmitCodeAlignment(4);
78
79 SwitchSection(getContext().getObjectFileInfo()->getBSSSection());
80 EmitCodeAlignment(4);
81
82 SwitchSection(getContext().getObjectFileInfo()->getTextSection());
83}
84
85void MCWinCOFFStreamer::EmitLabel(MCSymbol *S, SMLoc Loc) {
86 auto *Symbol = cast<MCSymbolCOFF>(S);
87 MCObjectStreamer::EmitLabel(Symbol, Loc);
88}
89
90void MCWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
91 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 91);
92}
93
94void MCWinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
95 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 95);
96}
97
98bool MCWinCOFFStreamer::EmitSymbolAttribute(MCSymbol *S,
99 MCSymbolAttr Attribute) {
100 auto *Symbol = cast<MCSymbolCOFF>(S);
101 getAssembler().registerSymbol(*Symbol);
102
103 switch (Attribute) {
104 default: return false;
105 case MCSA_WeakReference:
106 case MCSA_Weak:
107 Symbol->setIsWeakExternal();
108 Symbol->setExternal(true);
109 break;
110 case MCSA_Global:
111 Symbol->setExternal(true);
112 break;
113 case MCSA_AltEntry:
114 llvm_unreachable("COFF doesn't support the .alt_entry attribute")::llvm::llvm_unreachable_internal("COFF doesn't support the .alt_entry attribute"
, "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 114);
115 }
116
117 return true;
118}
119
120void MCWinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
121 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 121);
122}
123
124void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *S) {
125 auto *Symbol = cast<MCSymbolCOFF>(S);
126 if (CurSymbol)
127 Error("starting a new symbol definition without completing the "
128 "previous one");
129 CurSymbol = Symbol;
130}
131
132void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
133 if (!CurSymbol) {
134 Error("storage class specified outside of symbol definition");
135 return;
136 }
137
138 if (StorageClass & ~COFF::SSC_Invalid) {
139 Error("storage class value '" + Twine(StorageClass) +
140 "' out of range");
141 return;
142 }
143
144 getAssembler().registerSymbol(*CurSymbol);
145 cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass);
146}
147
148void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) {
149 if (!CurSymbol) {
150 Error("symbol type specified outside of a symbol definition");
151 return;
152 }
153
154 if (Type & ~0xffff) {
155 Error("type value '" + Twine(Type) + "' out of range");
156 return;
157 }
158
159 getAssembler().registerSymbol(*CurSymbol);
160 cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type);
161}
162
163void MCWinCOFFStreamer::EndCOFFSymbolDef() {
164 if (!CurSymbol)
165 Error("ending symbol definition without starting one");
166 CurSymbol = nullptr;
167}
168
169void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
170 // SafeSEH is a feature specific to 32-bit x86. It does not exist (and is
171 // unnecessary) on all platforms which use table-based exception dispatch.
172 if (getContext().getObjectFileInfo()->getTargetTriple().getArch() !=
173 Triple::x86)
174 return;
175
176 const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol);
177 if (CSymbol->isSafeSEH())
178 return;
179
180 MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
181 getAssembler().registerSection(*SXData);
182 if (SXData->getAlignment() < 4)
183 SXData->setAlignment(4);
184
185 new MCSymbolIdFragment(Symbol, SXData);
186
187 getAssembler().registerSymbol(*Symbol);
188 CSymbol->setIsSafeSEH();
189
190 // The Microsoft linker requires that the symbol type of a handler be
191 // function. Go ahead and oblige it here.
192 CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
193 << COFF::SCT_COMPLEX_TYPE_SHIFT);
194}
195
196void MCWinCOFFStreamer::EmitCOFFSectionIndex(const MCSymbol *Symbol) {
197 visitUsedSymbol(*Symbol);
198 MCDataFragment *DF = getOrCreateDataFragment();
199 const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
200 MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2);
201 DF->getFixups().push_back(Fixup);
202 DF->getContents().resize(DF->getContents().size() + 2, 0);
203}
204
205void MCWinCOFFStreamer::EmitCOFFSecRel32(const MCSymbol *Symbol,
206 uint64_t Offset) {
207 visitUsedSymbol(*Symbol);
208 MCDataFragment *DF = getOrCreateDataFragment();
209 // Create Symbol A for the relocation relative reference.
210 const MCExpr *MCE = MCSymbolRefExpr::create(Symbol, getContext());
211 // Add the constant offset, if given.
212 if (Offset)
213 MCE = MCBinaryExpr::createAdd(
214 MCE, MCConstantExpr::create(Offset, getContext()), getContext());
215 // Build the secrel32 relocation.
216 MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_SecRel_4);
217 // Record the relocation.
218 DF->getFixups().push_back(Fixup);
219 // Emit 4 bytes (zeros) to the object file.
220 DF->getContents().resize(DF->getContents().size() + 4, 0);
221}
222
223void MCWinCOFFStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
224 unsigned ByteAlignment) {
225 auto *Symbol = cast<MCSymbolCOFF>(S);
226
227 const Triple &T = getContext().getObjectFileInfo()->getTargetTriple();
228 if (T.isKnownWindowsMSVCEnvironment()) {
229 if (ByteAlignment > 32)
230 report_fatal_error("alignment is limited to 32-bytes");
231
232 // Round size up to alignment so that we will honor the alignment request.
233 Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
234 }
235
236 getAssembler().registerSymbol(*Symbol);
237 Symbol->setExternal(true);
238 Symbol->setCommon(Size, ByteAlignment);
239
240 if (!T.isKnownWindowsMSVCEnvironment() && ByteAlignment > 1) {
241 SmallString<128> Directive;
242 raw_svector_ostream OS(Directive);
243 const MCObjectFileInfo *MFI = getContext().getObjectFileInfo();
244
245 OS << " -aligncomm:\"" << Symbol->getName() << "\","
246 << Log2_32_Ceil(ByteAlignment);
247
248 PushSection();
249 SwitchSection(MFI->getDrectveSection());
250 EmitBytes(Directive);
251 PopSection();
252 }
253}
254
255void MCWinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
256 unsigned ByteAlignment) {
257 auto *Symbol = cast<MCSymbolCOFF>(S);
258
259 MCSection *Section = getContext().getObjectFileInfo()->getBSSSection();
260 getAssembler().registerSection(*Section);
261 if (Section->getAlignment() < ByteAlignment)
1
Taking false branch
→
262 Section->setAlignment(ByteAlignment);
263
264 getAssembler().registerSymbol(*Symbol);
265 Symbol->setExternal(false);
266
267 if (ByteAlignment != 1)
2
←
Assuming 'ByteAlignment' is equal to 1
→
3
←
Taking false branch
→
268 new MCAlignFragment(ByteAlignment, /*Value=*/0, /*ValueSize=*/0,
269 ByteAlignment, Section);
270
271 MCFillFragment *Fragment = new MCFillFragment(
4
←
Memory is allocated
→
272 /*Value=*/0, Size, Section);
273 Symbol->setFragment(Fragment);
274}
5
←
Potential leak of memory pointed to by 'Fragment'
275
276void MCWinCOFFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
277 uint64_t Size, unsigned ByteAlignment) {
278 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 278);
279}
280
281void MCWinCOFFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
282 uint64_t Size, unsigned ByteAlignment) {
283 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 283);
284}
285
286// TODO: Implement this if you want to emit .comment section in COFF obj files.
287void MCWinCOFFStreamer::EmitIdent(StringRef IdentString) {
288 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 288);
289}
290
291void MCWinCOFFStreamer::EmitWinEHHandlerData(SMLoc Loc) {
292 llvm_unreachable("not implemented")::llvm::llvm_unreachable_internal("not implemented", "/build/llvm-toolchain-snapshot-6.0~svn321639/lib/MC/MCWinCOFFStreamer.cpp"
, 292);
293}
294
295void MCWinCOFFStreamer::FinishImpl() {
296 MCObjectStreamer::FinishImpl();
297}
298
299void MCWinCOFFStreamer::Error(const Twine &Msg) const {
300 getContext().reportError(SMLoc(), Msg);
301}