Bug Summary

File:lib/MC/MCAssembler.cpp
Warning:line 582, column 15
Assigned value is garbage or undefined

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name MCAssembler.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/lib/MC -I /build/llvm-toolchain-snapshot-7~svn338205/lib/MC -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn338205/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/lib/gcc/x86_64-linux-gnu/8/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/lib/MC -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-07-29-043837-17923-1 -x c++ /build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp -faddrsig
1//===- lib/MC/MCAssembler.cpp - Assembler Backend 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/MC/MCAssembler.h"
11#include "llvm/ADT/ArrayRef.h"
12#include "llvm/ADT/SmallString.h"
13#include "llvm/ADT/SmallVector.h"
14#include "llvm/ADT/Statistic.h"
15#include "llvm/ADT/StringRef.h"
16#include "llvm/ADT/Twine.h"
17#include "llvm/MC/MCAsmBackend.h"
18#include "llvm/MC/MCAsmInfo.h"
19#include "llvm/MC/MCAsmLayout.h"
20#include "llvm/MC/MCCodeEmitter.h"
21#include "llvm/MC/MCCodeView.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCDwarf.h"
24#include "llvm/MC/MCExpr.h"
25#include "llvm/MC/MCFixup.h"
26#include "llvm/MC/MCFixupKindInfo.h"
27#include "llvm/MC/MCFragment.h"
28#include "llvm/MC/MCInst.h"
29#include "llvm/MC/MCObjectWriter.h"
30#include "llvm/MC/MCSection.h"
31#include "llvm/MC/MCSectionELF.h"
32#include "llvm/MC/MCSymbol.h"
33#include "llvm/MC/MCValue.h"
34#include "llvm/Support/Casting.h"
35#include "llvm/Support/Debug.h"
36#include "llvm/Support/ErrorHandling.h"
37#include "llvm/Support/LEB128.h"
38#include "llvm/Support/MathExtras.h"
39#include "llvm/Support/raw_ostream.h"
40#include <cassert>
41#include <cstdint>
42#include <cstring>
43#include <tuple>
44#include <utility>
45
46using namespace llvm;
47
48#define DEBUG_TYPE"assembler" "assembler"
49
50namespace {
51namespace stats {
52
53STATISTIC(EmittedFragments, "Number of emitted assembler fragments - total")static llvm::Statistic EmittedFragments = {"assembler", "EmittedFragments"
, "Number of emitted assembler fragments - total", {0}, {false
}}
;
54STATISTIC(EmittedRelaxableFragments,static llvm::Statistic EmittedRelaxableFragments = {"assembler"
, "EmittedRelaxableFragments", "Number of emitted assembler fragments - relaxable"
, {0}, {false}}
55 "Number of emitted assembler fragments - relaxable")static llvm::Statistic EmittedRelaxableFragments = {"assembler"
, "EmittedRelaxableFragments", "Number of emitted assembler fragments - relaxable"
, {0}, {false}}
;
56STATISTIC(EmittedDataFragments,static llvm::Statistic EmittedDataFragments = {"assembler", "EmittedDataFragments"
, "Number of emitted assembler fragments - data", {0}, {false
}}
57 "Number of emitted assembler fragments - data")static llvm::Statistic EmittedDataFragments = {"assembler", "EmittedDataFragments"
, "Number of emitted assembler fragments - data", {0}, {false
}}
;
58STATISTIC(EmittedCompactEncodedInstFragments,static llvm::Statistic EmittedCompactEncodedInstFragments = {
"assembler", "EmittedCompactEncodedInstFragments", "Number of emitted assembler fragments - compact encoded inst"
, {0}, {false}}
59 "Number of emitted assembler fragments - compact encoded inst")static llvm::Statistic EmittedCompactEncodedInstFragments = {
"assembler", "EmittedCompactEncodedInstFragments", "Number of emitted assembler fragments - compact encoded inst"
, {0}, {false}}
;
60STATISTIC(EmittedAlignFragments,static llvm::Statistic EmittedAlignFragments = {"assembler", "EmittedAlignFragments"
, "Number of emitted assembler fragments - align", {0}, {false
}}
61 "Number of emitted assembler fragments - align")static llvm::Statistic EmittedAlignFragments = {"assembler", "EmittedAlignFragments"
, "Number of emitted assembler fragments - align", {0}, {false
}}
;
62STATISTIC(EmittedFillFragments,static llvm::Statistic EmittedFillFragments = {"assembler", "EmittedFillFragments"
, "Number of emitted assembler fragments - fill", {0}, {false
}}
63 "Number of emitted assembler fragments - fill")static llvm::Statistic EmittedFillFragments = {"assembler", "EmittedFillFragments"
, "Number of emitted assembler fragments - fill", {0}, {false
}}
;
64STATISTIC(EmittedOrgFragments,static llvm::Statistic EmittedOrgFragments = {"assembler", "EmittedOrgFragments"
, "Number of emitted assembler fragments - org", {0}, {false}
}
65 "Number of emitted assembler fragments - org")static llvm::Statistic EmittedOrgFragments = {"assembler", "EmittedOrgFragments"
, "Number of emitted assembler fragments - org", {0}, {false}
}
;
66STATISTIC(evaluateFixup, "Number of evaluated fixups")static llvm::Statistic evaluateFixup = {"assembler", "evaluateFixup"
, "Number of evaluated fixups", {0}, {false}}
;
67STATISTIC(FragmentLayouts, "Number of fragment layouts")static llvm::Statistic FragmentLayouts = {"assembler", "FragmentLayouts"
, "Number of fragment layouts", {0}, {false}}
;
68STATISTIC(ObjectBytes, "Number of emitted object file bytes")static llvm::Statistic ObjectBytes = {"assembler", "ObjectBytes"
, "Number of emitted object file bytes", {0}, {false}}
;
69STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps")static llvm::Statistic RelaxationSteps = {"assembler", "RelaxationSteps"
, "Number of assembler layout and relaxation steps", {0}, {false
}}
;
70STATISTIC(RelaxedInstructions, "Number of relaxed instructions")static llvm::Statistic RelaxedInstructions = {"assembler", "RelaxedInstructions"
, "Number of relaxed instructions", {0}, {false}}
;
71STATISTIC(PaddingFragmentsRelaxations,static llvm::Statistic PaddingFragmentsRelaxations = {"assembler"
, "PaddingFragmentsRelaxations", "Number of Padding Fragments relaxations"
, {0}, {false}}
72 "Number of Padding Fragments relaxations")static llvm::Statistic PaddingFragmentsRelaxations = {"assembler"
, "PaddingFragmentsRelaxations", "Number of Padding Fragments relaxations"
, {0}, {false}}
;
73STATISTIC(PaddingFragmentsBytes,static llvm::Statistic PaddingFragmentsBytes = {"assembler", "PaddingFragmentsBytes"
, "Total size of all padding from adding Fragments", {0}, {false
}}
74 "Total size of all padding from adding Fragments")static llvm::Statistic PaddingFragmentsBytes = {"assembler", "PaddingFragmentsBytes"
, "Total size of all padding from adding Fragments", {0}, {false
}}
;
75
76} // end namespace stats
77} // end anonymous namespace
78
79// FIXME FIXME FIXME: There are number of places in this file where we convert
80// what is a 64-bit assembler value used for computation into a value in the
81// object file, which may truncate it. We should detect that truncation where
82// invalid and report errors back.
83
84/* *** */
85
86MCAssembler::MCAssembler(MCContext &Context,
87 std::unique_ptr<MCAsmBackend> Backend,
88 std::unique_ptr<MCCodeEmitter> Emitter,
89 std::unique_ptr<MCObjectWriter> Writer)
90 : Context(Context), Backend(std::move(Backend)),
91 Emitter(std::move(Emitter)), Writer(std::move(Writer)),
92 BundleAlignSize(0), RelaxAll(false), SubsectionsViaSymbols(false),
93 IncrementalLinkerCompatible(false), ELFHeaderEFlags(0) {
94 VersionInfo.Major = 0; // Major version == 0 for "none specified"
95}
96
97MCAssembler::~MCAssembler() = default;
98
99void MCAssembler::reset() {
100 Sections.clear();
101 Symbols.clear();
102 IndirectSymbols.clear();
103 DataRegions.clear();
104 LinkerOptions.clear();
105 FileNames.clear();
106 ThumbFuncs.clear();
107 BundleAlignSize = 0;
108 RelaxAll = false;
109 SubsectionsViaSymbols = false;
110 IncrementalLinkerCompatible = false;
111 ELFHeaderEFlags = 0;
112 LOHContainer.reset();
113 VersionInfo.Major = 0;
114
115 // reset objects owned by us
116 if (getBackendPtr())
117 getBackendPtr()->reset();
118 if (getEmitterPtr())
119 getEmitterPtr()->reset();
120 if (getWriterPtr())
121 getWriterPtr()->reset();
122 getLOHContainer().reset();
123}
124
125bool MCAssembler::registerSection(MCSection &Section) {
126 if (Section.isRegistered())
127 return false;
128 Sections.push_back(&Section);
129 Section.setIsRegistered(true);
130 return true;
131}
132
133bool MCAssembler::isThumbFunc(const MCSymbol *Symbol) const {
134 if (ThumbFuncs.count(Symbol))
135 return true;
136
137 if (!Symbol->isVariable())
138 return false;
139
140 const MCExpr *Expr = Symbol->getVariableValue();
141
142 MCValue V;
143 if (!Expr->evaluateAsRelocatable(V, nullptr, nullptr))
144 return false;
145
146 if (V.getSymB() || V.getRefKind() != MCSymbolRefExpr::VK_None)
147 return false;
148
149 const MCSymbolRefExpr *Ref = V.getSymA();
150 if (!Ref)
151 return false;
152
153 if (Ref->getKind() != MCSymbolRefExpr::VK_None)
154 return false;
155
156 const MCSymbol &Sym = Ref->getSymbol();
157 if (!isThumbFunc(&Sym))
158 return false;
159
160 ThumbFuncs.insert(Symbol); // Cache it.
161 return true;
162}
163
164bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
165 // Non-temporary labels should always be visible to the linker.
166 if (!Symbol.isTemporary())
167 return true;
168
169 // Absolute temporary labels are never visible.
170 if (!Symbol.isInSection())
171 return false;
172
173 if (Symbol.isUsedInReloc())
174 return true;
175
176 return false;
177}
178
179const MCSymbol *MCAssembler::getAtom(const MCSymbol &S) const {
180 // Linker visible symbols define atoms.
181 if (isSymbolLinkerVisible(S))
182 return &S;
183
184 // Absolute and undefined symbols have no defining atom.
185 if (!S.isInSection())
186 return nullptr;
187
188 // Non-linker visible symbols in sections which can't be atomized have no
189 // defining atom.
190 if (!getContext().getAsmInfo()->isSectionAtomizableBySymbols(
191 *S.getFragment()->getParent()))
192 return nullptr;
193
194 // Otherwise, return the atom for the containing fragment.
195 return S.getFragment()->getAtom();
196}
197
198bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout,
199 const MCFixup &Fixup, const MCFragment *DF,
200 MCValue &Target, uint64_t &Value,
201 bool &WasForced) const {
202 ++stats::evaluateFixup;
203
204 // FIXME: This code has some duplication with recordRelocation. We should
205 // probably merge the two into a single callback that tries to evaluate a
206 // fixup and records a relocation if one is needed.
207
208 // On error claim to have completely evaluated the fixup, to prevent any
209 // further processing from being done.
210 const MCExpr *Expr = Fixup.getValue();
211 MCContext &Ctx = getContext();
212 Value = 0;
213 WasForced = false;
214 if (!Expr->evaluateAsRelocatable(Target, &Layout, &Fixup)) {
215 Ctx.reportError(Fixup.getLoc(), "expected relocatable expression");
216 return true;
217 }
218 if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
219 if (RefB->getKind() != MCSymbolRefExpr::VK_None) {
220 Ctx.reportError(Fixup.getLoc(),
221 "unsupported subtraction of qualified symbol");
222 return true;
223 }
224 }
225
226 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 226, __extension__ __PRETTY_FUNCTION__))
;
227 bool IsPCRel = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
228 MCFixupKindInfo::FKF_IsPCRel;
229
230 bool IsResolved = false;
231 if (IsPCRel) {
232 if (Target.getSymB()) {
233 IsResolved = false;
234 } else if (!Target.getSymA()) {
235 IsResolved = false;
236 } else {
237 const MCSymbolRefExpr *A = Target.getSymA();
238 const MCSymbol &SA = A->getSymbol();
239 if (A->getKind() != MCSymbolRefExpr::VK_None || SA.isUndefined()) {
240 IsResolved = false;
241 } else if (auto *Writer = getWriterPtr()) {
242 IsResolved = Writer->isSymbolRefDifferenceFullyResolvedImpl(
243 *this, SA, *DF, false, true);
244 }
245 }
246 } else {
247 IsResolved = Target.isAbsolute();
248 }
249
250 Value = Target.getConstant();
251
252 if (const MCSymbolRefExpr *A = Target.getSymA()) {
253 const MCSymbol &Sym = A->getSymbol();
254 if (Sym.isDefined())
255 Value += Layout.getSymbolOffset(Sym);
256 }
257 if (const MCSymbolRefExpr *B = Target.getSymB()) {
258 const MCSymbol &Sym = B->getSymbol();
259 if (Sym.isDefined())
260 Value -= Layout.getSymbolOffset(Sym);
261 }
262
263 bool ShouldAlignPC = getBackend().getFixupKindInfo(Fixup.getKind()).Flags &
264 MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
265 assert((ShouldAlignPC ? IsPCRel : true) &&(static_cast <bool> ((ShouldAlignPC ? IsPCRel : true) &&
"FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!"
) ? void (0) : __assert_fail ("(ShouldAlignPC ? IsPCRel : true) && \"FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 266, __extension__ __PRETTY_FUNCTION__))
266 "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!")(static_cast <bool> ((ShouldAlignPC ? IsPCRel : true) &&
"FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!"
) ? void (0) : __assert_fail ("(ShouldAlignPC ? IsPCRel : true) && \"FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 266, __extension__ __PRETTY_FUNCTION__))
;
267
268 if (IsPCRel) {
269 uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset();
270
271 // A number of ARM fixups in Thumb mode require that the effective PC
272 // address be determined as the 32-bit aligned version of the actual offset.
273 if (ShouldAlignPC) Offset &= ~0x3;
274 Value -= Offset;
275 }
276
277 // Let the backend force a relocation if needed.
278 if (IsResolved && getBackend().shouldForceRelocation(*this, Fixup, Target)) {
279 IsResolved = false;
280 WasForced = true;
281 }
282
283 return IsResolved;
284}
285
286uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
287 const MCFragment &F) const {
288 assert(getBackendPtr() && "Requires assembler backend")(static_cast <bool> (getBackendPtr() && "Requires assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Requires assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 288, __extension__ __PRETTY_FUNCTION__))
;
289 switch (F.getKind()) {
290 case MCFragment::FT_Data:
291 return cast<MCDataFragment>(F).getContents().size();
292 case MCFragment::FT_Relaxable:
293 return cast<MCRelaxableFragment>(F).getContents().size();
294 case MCFragment::FT_CompactEncodedInst:
295 return cast<MCCompactEncodedInstFragment>(F).getContents().size();
296 case MCFragment::FT_Fill: {
297 auto &FF = cast<MCFillFragment>(F);
298 int64_t NumValues = 0;
299 if (!FF.getNumValues().evaluateAsAbsolute(NumValues, Layout)) {
300 getContext().reportError(FF.getLoc(),
301 "expected assembly-time absolute expression");
302 return 0;
303 }
304 int64_t Size = NumValues * FF.getValueSize();
305 if (Size < 0) {
306 getContext().reportError(FF.getLoc(), "invalid number of bytes");
307 return 0;
308 }
309 return Size;
310 }
311
312 case MCFragment::FT_LEB:
313 return cast<MCLEBFragment>(F).getContents().size();
314
315 case MCFragment::FT_Padding:
316 return cast<MCPaddingFragment>(F).getSize();
317
318 case MCFragment::FT_SymbolId:
319 return 4;
320
321 case MCFragment::FT_Align: {
322 const MCAlignFragment &AF = cast<MCAlignFragment>(F);
323 unsigned Offset = Layout.getFragmentOffset(&AF);
324 unsigned Size = OffsetToAlignment(Offset, AF.getAlignment());
325 // If we are padding with nops, force the padding to be larger than the
326 // minimum nop size.
327 if (Size > 0 && AF.hasEmitNops()) {
328 while (Size % getBackend().getMinimumNopSize())
329 Size += AF.getAlignment();
330 }
331 if (Size > AF.getMaxBytesToEmit())
332 return 0;
333 return Size;
334 }
335
336 case MCFragment::FT_Org: {
337 const MCOrgFragment &OF = cast<MCOrgFragment>(F);
338 MCValue Value;
339 if (!OF.getOffset().evaluateAsValue(Value, Layout)) {
340 getContext().reportError(OF.getLoc(),
341 "expected assembly-time absolute expression");
342 return 0;
343 }
344
345 uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
346 int64_t TargetLocation = Value.getConstant();
347 if (const MCSymbolRefExpr *A = Value.getSymA()) {
348 uint64_t Val;
349 if (!Layout.getSymbolOffset(A->getSymbol(), Val)) {
350 getContext().reportError(OF.getLoc(), "expected absolute expression");
351 return 0;
352 }
353 TargetLocation += Val;
354 }
355 int64_t Size = TargetLocation - FragmentOffset;
356 if (Size < 0 || Size >= 0x40000000) {
357 getContext().reportError(
358 OF.getLoc(), "invalid .org offset '" + Twine(TargetLocation) +
359 "' (at offset '" + Twine(FragmentOffset) + "')");
360 return 0;
361 }
362 return Size;
363 }
364
365 case MCFragment::FT_Dwarf:
366 return cast<MCDwarfLineAddrFragment>(F).getContents().size();
367 case MCFragment::FT_DwarfFrame:
368 return cast<MCDwarfCallFrameFragment>(F).getContents().size();
369 case MCFragment::FT_CVInlineLines:
370 return cast<MCCVInlineLineTableFragment>(F).getContents().size();
371 case MCFragment::FT_CVDefRange:
372 return cast<MCCVDefRangeFragment>(F).getContents().size();
373 case MCFragment::FT_Dummy:
374 llvm_unreachable("Should not have been added")::llvm::llvm_unreachable_internal("Should not have been added"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 374)
;
375 }
376
377 llvm_unreachable("invalid fragment kind")::llvm::llvm_unreachable_internal("invalid fragment kind", "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 377)
;
378}
379
380void MCAsmLayout::layoutFragment(MCFragment *F) {
381 MCFragment *Prev = F->getPrevNode();
382
383 // We should never try to recompute something which is valid.
384 assert(!isFragmentValid(F) && "Attempt to recompute a valid fragment!")(static_cast <bool> (!isFragmentValid(F) && "Attempt to recompute a valid fragment!"
) ? void (0) : __assert_fail ("!isFragmentValid(F) && \"Attempt to recompute a valid fragment!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 384, __extension__ __PRETTY_FUNCTION__))
;
385 // We should never try to compute the fragment layout if its predecessor
386 // isn't valid.
387 assert((!Prev || isFragmentValid(Prev)) &&(static_cast <bool> ((!Prev || isFragmentValid(Prev)) &&
"Attempt to compute fragment before its predecessor!") ? void
(0) : __assert_fail ("(!Prev || isFragmentValid(Prev)) && \"Attempt to compute fragment before its predecessor!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 388, __extension__ __PRETTY_FUNCTION__))
388 "Attempt to compute fragment before its predecessor!")(static_cast <bool> ((!Prev || isFragmentValid(Prev)) &&
"Attempt to compute fragment before its predecessor!") ? void
(0) : __assert_fail ("(!Prev || isFragmentValid(Prev)) && \"Attempt to compute fragment before its predecessor!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 388, __extension__ __PRETTY_FUNCTION__))
;
389
390 ++stats::FragmentLayouts;
391
392 // Compute fragment offset and size.
393 if (Prev)
394 F->Offset = Prev->Offset + getAssembler().computeFragmentSize(*this, *Prev);
395 else
396 F->Offset = 0;
397 LastValidFragment[F->getParent()] = F;
398
399 // If bundling is enabled and this fragment has instructions in it, it has to
400 // obey the bundling restrictions. With padding, we'll have:
401 //
402 //
403 // BundlePadding
404 // |||
405 // -------------------------------------
406 // Prev |##########| F |
407 // -------------------------------------
408 // ^
409 // |
410 // F->Offset
411 //
412 // The fragment's offset will point to after the padding, and its computed
413 // size won't include the padding.
414 //
415 // When the -mc-relax-all flag is used, we optimize bundling by writting the
416 // padding directly into fragments when the instructions are emitted inside
417 // the streamer. When the fragment is larger than the bundle size, we need to
418 // ensure that it's bundle aligned. This means that if we end up with
419 // multiple fragments, we must emit bundle padding between fragments.
420 //
421 // ".align N" is an example of a directive that introduces multiple
422 // fragments. We could add a special case to handle ".align N" by emitting
423 // within-fragment padding (which would produce less padding when N is less
424 // than the bundle size), but for now we don't.
425 //
426 if (Assembler.isBundlingEnabled() && F->hasInstructions()) {
427 assert(isa<MCEncodedFragment>(F) &&(static_cast <bool> (isa<MCEncodedFragment>(F) &&
"Only MCEncodedFragment implementations have instructions") ?
void (0) : __assert_fail ("isa<MCEncodedFragment>(F) && \"Only MCEncodedFragment implementations have instructions\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 428, __extension__ __PRETTY_FUNCTION__))
428 "Only MCEncodedFragment implementations have instructions")(static_cast <bool> (isa<MCEncodedFragment>(F) &&
"Only MCEncodedFragment implementations have instructions") ?
void (0) : __assert_fail ("isa<MCEncodedFragment>(F) && \"Only MCEncodedFragment implementations have instructions\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 428, __extension__ __PRETTY_FUNCTION__))
;
429 MCEncodedFragment *EF = cast<MCEncodedFragment>(F);
430 uint64_t FSize = Assembler.computeFragmentSize(*this, *EF);
431
432 if (!Assembler.getRelaxAll() && FSize > Assembler.getBundleAlignSize())
433 report_fatal_error("Fragment can't be larger than a bundle size");
434
435 uint64_t RequiredBundlePadding =
436 computeBundlePadding(Assembler, EF, EF->Offset, FSize);
437 if (RequiredBundlePadding > UINT8_MAX(255))
438 report_fatal_error("Padding cannot exceed 255 bytes");
439 EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
440 EF->Offset += RequiredBundlePadding;
441 }
442}
443
444void MCAssembler::registerSymbol(const MCSymbol &Symbol, bool *Created) {
445 bool New = !Symbol.isRegistered();
446 if (Created)
447 *Created = New;
448 if (New) {
449 Symbol.setIsRegistered(true);
450 Symbols.push_back(&Symbol);
451 }
452}
453
454void MCAssembler::writeFragmentPadding(raw_ostream &OS,
455 const MCEncodedFragment &EF,
456 uint64_t FSize) const {
457 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 457, __extension__ __PRETTY_FUNCTION__))
;
458 // Should NOP padding be written out before this fragment?
459 unsigned BundlePadding = EF.getBundlePadding();
460 if (BundlePadding > 0) {
461 assert(isBundlingEnabled() &&(static_cast <bool> (isBundlingEnabled() && "Writing bundle padding with disabled bundling"
) ? void (0) : __assert_fail ("isBundlingEnabled() && \"Writing bundle padding with disabled bundling\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 462, __extension__ __PRETTY_FUNCTION__))
462 "Writing bundle padding with disabled bundling")(static_cast <bool> (isBundlingEnabled() && "Writing bundle padding with disabled bundling"
) ? void (0) : __assert_fail ("isBundlingEnabled() && \"Writing bundle padding with disabled bundling\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 462, __extension__ __PRETTY_FUNCTION__))
;
463 assert(EF.hasInstructions() &&(static_cast <bool> (EF.hasInstructions() && "Writing bundle padding for a fragment without instructions"
) ? void (0) : __assert_fail ("EF.hasInstructions() && \"Writing bundle padding for a fragment without instructions\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 464, __extension__ __PRETTY_FUNCTION__))
464 "Writing bundle padding for a fragment without instructions")(static_cast <bool> (EF.hasInstructions() && "Writing bundle padding for a fragment without instructions"
) ? void (0) : __assert_fail ("EF.hasInstructions() && \"Writing bundle padding for a fragment without instructions\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 464, __extension__ __PRETTY_FUNCTION__))
;
465
466 unsigned TotalLength = BundlePadding + static_cast<unsigned>(FSize);
467 if (EF.alignToBundleEnd() && TotalLength > getBundleAlignSize()) {
468 // If the padding itself crosses a bundle boundary, it must be emitted
469 // in 2 pieces, since even nop instructions must not cross boundaries.
470 // v--------------v <- BundleAlignSize
471 // v---------v <- BundlePadding
472 // ----------------------------
473 // | Prev |####|####| F |
474 // ----------------------------
475 // ^-------------------^ <- TotalLength
476 unsigned DistanceToBoundary = TotalLength - getBundleAlignSize();
477 if (!getBackend().writeNopData(OS, DistanceToBoundary))
478 report_fatal_error("unable to write NOP sequence of " +
479 Twine(DistanceToBoundary) + " bytes");
480 BundlePadding -= DistanceToBoundary;
481 }
482 if (!getBackend().writeNopData(OS, BundlePadding))
483 report_fatal_error("unable to write NOP sequence of " +
484 Twine(BundlePadding) + " bytes");
485 }
486}
487
488/// Write the fragment \p F to the output file.
489static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
490 const MCAsmLayout &Layout, const MCFragment &F) {
491 // FIXME: Embed in fragments instead?
492 uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);
493
494 support::endianness Endian = Asm.getBackend().Endian;
495
496 if (const MCEncodedFragment *EF = dyn_cast<MCEncodedFragment>(&F))
4
Taking false branch
497 Asm.writeFragmentPadding(OS, *EF, FragmentSize);
498
499 // This variable (and its dummy usage) is to participate in the assert at
500 // the end of the function.
501 uint64_t Start = OS.tell();
502 (void) Start;
503
504 ++stats::EmittedFragments;
505
506 switch (F.getKind()) {
5
Control jumps to 'case FT_Fill:' at line 568
507 case MCFragment::FT_Align: {
508 ++stats::EmittedAlignFragments;
509 const MCAlignFragment &AF = cast<MCAlignFragment>(F);
510 assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!")(static_cast <bool> (AF.getValueSize() && "Invalid virtual align in concrete fragment!"
) ? void (0) : __assert_fail ("AF.getValueSize() && \"Invalid virtual align in concrete fragment!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 510, __extension__ __PRETTY_FUNCTION__))
;
511
512 uint64_t Count = FragmentSize / AF.getValueSize();
513
514 // FIXME: This error shouldn't actually occur (the front end should emit
515 // multiple .align directives to enforce the semantics it wants), but is
516 // severe enough that we want to report it. How to handle this?
517 if (Count * AF.getValueSize() != FragmentSize)
518 report_fatal_error("undefined .align directive, value size '" +
519 Twine(AF.getValueSize()) +
520 "' is not a divisor of padding size '" +
521 Twine(FragmentSize) + "'");
522
523 // See if we are aligning with nops, and if so do that first to try to fill
524 // the Count bytes. Then if that did not fill any bytes or there are any
525 // bytes left to fill use the Value and ValueSize to fill the rest.
526 // If we are aligning with nops, ask that target to emit the right data.
527 if (AF.hasEmitNops()) {
528 if (!Asm.getBackend().writeNopData(OS, Count))
529 report_fatal_error("unable to write nop sequence of " +
530 Twine(Count) + " bytes");
531 break;
532 }
533
534 // Otherwise, write out in multiples of the value size.
535 for (uint64_t i = 0; i != Count; ++i) {
536 switch (AF.getValueSize()) {
537 default: llvm_unreachable("Invalid size!")::llvm::llvm_unreachable_internal("Invalid size!", "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 537)
;
538 case 1: OS << char(AF.getValue()); break;
539 case 2:
540 support::endian::write<uint16_t>(OS, AF.getValue(), Endian);
541 break;
542 case 4:
543 support::endian::write<uint32_t>(OS, AF.getValue(), Endian);
544 break;
545 case 8:
546 support::endian::write<uint64_t>(OS, AF.getValue(), Endian);
547 break;
548 }
549 }
550 break;
551 }
552
553 case MCFragment::FT_Data:
554 ++stats::EmittedDataFragments;
555 OS << cast<MCDataFragment>(F).getContents();
556 break;
557
558 case MCFragment::FT_Relaxable:
559 ++stats::EmittedRelaxableFragments;
560 OS << cast<MCRelaxableFragment>(F).getContents();
561 break;
562
563 case MCFragment::FT_CompactEncodedInst:
564 ++stats::EmittedCompactEncodedInstFragments;
565 OS << cast<MCCompactEncodedInstFragment>(F).getContents();
566 break;
567
568 case MCFragment::FT_Fill: {
569 ++stats::EmittedFillFragments;
570 const MCFillFragment &FF = cast<MCFillFragment>(F);
571 uint64_t V = FF.getValue();
572 unsigned VSize = FF.getValueSize();
573 const unsigned MaxChunkSize = 16;
574 char Data[MaxChunkSize];
575 // Duplicate V into Data as byte vector to reduce number of
576 // writes done. As such, do endian conversion here.
577 for (unsigned I = 0; I != VSize; ++I) {
6
Assuming 'I' is equal to 'VSize'
7
Loop condition is false. Execution continues on line 581
578 unsigned index = Endian == support::little ? I : (VSize - I - 1);
579 Data[I] = uint8_t(V >> (index * 8));
580 }
581 for (unsigned I = VSize; I < MaxChunkSize; ++I)
8
Loop condition is true. Entering loop body
582 Data[I] = Data[I - VSize];
9
Assigned value is garbage or undefined
583
584 // Set to largest multiple of VSize in Data.
585 const unsigned NumPerChunk = MaxChunkSize / VSize;
586 // Set ChunkSize to largest multiple of VSize in Data
587 const unsigned ChunkSize = VSize * NumPerChunk;
588
589 // Do copies by chunk.
590 StringRef Ref(Data, ChunkSize);
591 for (uint64_t I = 0, E = FragmentSize / ChunkSize; I != E; ++I)
592 OS << Ref;
593
594 // do remainder if needed.
595 unsigned TrailingCount = FragmentSize % ChunkSize;
596 if (TrailingCount)
597 OS.write(Data, TrailingCount);
598 break;
599 }
600
601 case MCFragment::FT_LEB: {
602 const MCLEBFragment &LF = cast<MCLEBFragment>(F);
603 OS << LF.getContents();
604 break;
605 }
606
607 case MCFragment::FT_Padding: {
608 if (!Asm.getBackend().writeNopData(OS, FragmentSize))
609 report_fatal_error("unable to write nop sequence of " +
610 Twine(FragmentSize) + " bytes");
611 break;
612 }
613
614 case MCFragment::FT_SymbolId: {
615 const MCSymbolIdFragment &SF = cast<MCSymbolIdFragment>(F);
616 support::endian::write<uint32_t>(OS, SF.getSymbol()->getIndex(), Endian);
617 break;
618 }
619
620 case MCFragment::FT_Org: {
621 ++stats::EmittedOrgFragments;
622 const MCOrgFragment &OF = cast<MCOrgFragment>(F);
623
624 for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
625 OS << char(OF.getValue());
626
627 break;
628 }
629
630 case MCFragment::FT_Dwarf: {
631 const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
632 OS << OF.getContents();
633 break;
634 }
635 case MCFragment::FT_DwarfFrame: {
636 const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
637 OS << CF.getContents();
638 break;
639 }
640 case MCFragment::FT_CVInlineLines: {
641 const auto &OF = cast<MCCVInlineLineTableFragment>(F);
642 OS << OF.getContents();
643 break;
644 }
645 case MCFragment::FT_CVDefRange: {
646 const auto &DRF = cast<MCCVDefRangeFragment>(F);
647 OS << DRF.getContents();
648 break;
649 }
650 case MCFragment::FT_Dummy:
651 llvm_unreachable("Should not have been added")::llvm::llvm_unreachable_internal("Should not have been added"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 651)
;
652 }
653
654 assert(OS.tell() - Start == FragmentSize &&(static_cast <bool> (OS.tell() - Start == FragmentSize &&
"The stream should advance by fragment size") ? void (0) : __assert_fail
("OS.tell() - Start == FragmentSize && \"The stream should advance by fragment size\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 655, __extension__ __PRETTY_FUNCTION__))
655 "The stream should advance by fragment size")(static_cast <bool> (OS.tell() - Start == FragmentSize &&
"The stream should advance by fragment size") ? void (0) : __assert_fail
("OS.tell() - Start == FragmentSize && \"The stream should advance by fragment size\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 655, __extension__ __PRETTY_FUNCTION__))
;
656}
657
658void MCAssembler::writeSectionData(raw_ostream &OS, const MCSection *Sec,
659 const MCAsmLayout &Layout) const {
660 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 660, __extension__ __PRETTY_FUNCTION__))
;
661
662 // Ignore virtual sections.
663 if (Sec->isVirtualSection()) {
1
Assuming the condition is false
2
Taking false branch
664 assert(Layout.getSectionFileSize(Sec) == 0 && "Invalid size for section!")(static_cast <bool> (Layout.getSectionFileSize(Sec) == 0
&& "Invalid size for section!") ? void (0) : __assert_fail
("Layout.getSectionFileSize(Sec) == 0 && \"Invalid size for section!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 664, __extension__ __PRETTY_FUNCTION__))
;
665
666 // Check that contents are only things legal inside a virtual section.
667 for (const MCFragment &F : *Sec) {
668 switch (F.getKind()) {
669 default: llvm_unreachable("Invalid fragment in virtual section!")::llvm::llvm_unreachable_internal("Invalid fragment in virtual section!"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 669)
;
670 case MCFragment::FT_Data: {
671 // Check that we aren't trying to write a non-zero contents (or fixups)
672 // into a virtual section. This is to support clients which use standard
673 // directives to fill the contents of virtual sections.
674 const MCDataFragment &DF = cast<MCDataFragment>(F);
675 if (DF.fixup_begin() != DF.fixup_end())
676 report_fatal_error("cannot have fixups in virtual section!");
677 for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
678 if (DF.getContents()[i]) {
679 if (auto *ELFSec = dyn_cast<const MCSectionELF>(Sec))
680 report_fatal_error("non-zero initializer found in section '" +
681 ELFSec->getSectionName() + "'");
682 else
683 report_fatal_error("non-zero initializer found in virtual section");
684 }
685 break;
686 }
687 case MCFragment::FT_Align:
688 // Check that we aren't trying to write a non-zero value into a virtual
689 // section.
690 assert((cast<MCAlignFragment>(F).getValueSize() == 0 ||(static_cast <bool> ((cast<MCAlignFragment>(F).getValueSize
() == 0 || cast<MCAlignFragment>(F).getValue() == 0) &&
"Invalid align in virtual section!") ? void (0) : __assert_fail
("(cast<MCAlignFragment>(F).getValueSize() == 0 || cast<MCAlignFragment>(F).getValue() == 0) && \"Invalid align in virtual section!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 692, __extension__ __PRETTY_FUNCTION__))
691 cast<MCAlignFragment>(F).getValue() == 0) &&(static_cast <bool> ((cast<MCAlignFragment>(F).getValueSize
() == 0 || cast<MCAlignFragment>(F).getValue() == 0) &&
"Invalid align in virtual section!") ? void (0) : __assert_fail
("(cast<MCAlignFragment>(F).getValueSize() == 0 || cast<MCAlignFragment>(F).getValue() == 0) && \"Invalid align in virtual section!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 692, __extension__ __PRETTY_FUNCTION__))
692 "Invalid align in virtual section!")(static_cast <bool> ((cast<MCAlignFragment>(F).getValueSize
() == 0 || cast<MCAlignFragment>(F).getValue() == 0) &&
"Invalid align in virtual section!") ? void (0) : __assert_fail
("(cast<MCAlignFragment>(F).getValueSize() == 0 || cast<MCAlignFragment>(F).getValue() == 0) && \"Invalid align in virtual section!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 692, __extension__ __PRETTY_FUNCTION__))
;
693 break;
694 case MCFragment::FT_Fill:
695 assert((cast<MCFillFragment>(F).getValue() == 0) &&(static_cast <bool> ((cast<MCFillFragment>(F).getValue
() == 0) && "Invalid fill in virtual section!") ? void
(0) : __assert_fail ("(cast<MCFillFragment>(F).getValue() == 0) && \"Invalid fill in virtual section!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 696, __extension__ __PRETTY_FUNCTION__))
696 "Invalid fill in virtual section!")(static_cast <bool> ((cast<MCFillFragment>(F).getValue
() == 0) && "Invalid fill in virtual section!") ? void
(0) : __assert_fail ("(cast<MCFillFragment>(F).getValue() == 0) && \"Invalid fill in virtual section!\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 696, __extension__ __PRETTY_FUNCTION__))
;
697 break;
698 }
699 }
700
701 return;
702 }
703
704 uint64_t Start = OS.tell();
705 (void)Start;
706
707 for (const MCFragment &F : *Sec)
708 writeFragment(OS, *this, Layout, F);
3
Calling 'writeFragment'
709
710 assert(OS.tell() - Start == Layout.getSectionAddressSize(Sec))(static_cast <bool> (OS.tell() - Start == Layout.getSectionAddressSize
(Sec)) ? void (0) : __assert_fail ("OS.tell() - Start == Layout.getSectionAddressSize(Sec)"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 710, __extension__ __PRETTY_FUNCTION__))
;
711}
712
713std::tuple<MCValue, uint64_t, bool>
714MCAssembler::handleFixup(const MCAsmLayout &Layout, MCFragment &F,
715 const MCFixup &Fixup) {
716 // Evaluate the fixup.
717 MCValue Target;
718 uint64_t FixedValue;
719 bool WasForced;
720 bool IsResolved = evaluateFixup(Layout, Fixup, &F, Target, FixedValue,
721 WasForced);
722 if (!IsResolved) {
723 // The fixup was unresolved, we need a relocation. Inform the object
724 // writer of the relocation, and give it an opportunity to adjust the
725 // fixup value if need be.
726 if (Target.getSymA() && Target.getSymB() &&
727 getBackend().requiresDiffExpressionRelocations()) {
728 // The fixup represents the difference between two symbols, which the
729 // backend has indicated must be resolved at link time. Split up the fixup
730 // into two relocations, one for the add, and one for the sub, and emit
731 // both of these. The constant will be associated with the add half of the
732 // expression.
733 MCFixup FixupAdd = MCFixup::createAddFor(Fixup);
734 MCValue TargetAdd =
735 MCValue::get(Target.getSymA(), nullptr, Target.getConstant());
736 getWriter().recordRelocation(*this, Layout, &F, FixupAdd, TargetAdd,
737 FixedValue);
738 MCFixup FixupSub = MCFixup::createSubFor(Fixup);
739 MCValue TargetSub = MCValue::get(Target.getSymB());
740 getWriter().recordRelocation(*this, Layout, &F, FixupSub, TargetSub,
741 FixedValue);
742 } else {
743 getWriter().recordRelocation(*this, Layout, &F, Fixup, Target,
744 FixedValue);
745 }
746 }
747 return std::make_tuple(Target, FixedValue, IsResolved);
748}
749
750void MCAssembler::layout(MCAsmLayout &Layout) {
751 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 751, __extension__ __PRETTY_FUNCTION__))
;
752 DEBUG_WITH_TYPE("mc-dump", {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - pre-layout\n--\n"
; dump(); }; } } while (false)
753 errs() << "assembler backend - pre-layout\n--\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - pre-layout\n--\n"
; dump(); }; } } while (false)
754 dump(); })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - pre-layout\n--\n"
; dump(); }; } } while (false)
;
755
756 // Create dummy fragments and assign section ordinals.
757 unsigned SectionIndex = 0;
758 for (MCSection &Sec : *this) {
759 // Create dummy fragments to eliminate any empty sections, this simplifies
760 // layout.
761 if (Sec.getFragmentList().empty())
762 new MCDataFragment(&Sec);
763
764 Sec.setOrdinal(SectionIndex++);
765 }
766
767 // Assign layout order indices to sections and fragments.
768 for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
769 MCSection *Sec = Layout.getSectionOrder()[i];
770 Sec->setLayoutOrder(i);
771
772 unsigned FragmentIndex = 0;
773 for (MCFragment &Frag : *Sec)
774 Frag.setLayoutOrder(FragmentIndex++);
775 }
776
777 // Layout until everything fits.
778 while (layoutOnce(Layout))
779 if (getContext().hadError())
780 return;
781
782 DEBUG_WITH_TYPE("mc-dump", {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - post-relaxation\n--\n"
; dump(); }; } } while (false)
783 errs() << "assembler backend - post-relaxation\n--\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - post-relaxation\n--\n"
; dump(); }; } } while (false)
784 dump(); })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - post-relaxation\n--\n"
; dump(); }; } } while (false)
;
785
786 // Finalize the layout, including fragment lowering.
787 finishLayout(Layout);
788
789 DEBUG_WITH_TYPE("mc-dump", {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - final-layout\n--\n"
; dump(); }; } } while (false)
790 errs() << "assembler backend - final-layout\n--\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - final-layout\n--\n"
; dump(); }; } } while (false)
791 dump(); })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("mc-dump")) { { errs() << "assembler backend - final-layout\n--\n"
; dump(); }; } } while (false)
;
792
793 // Allow the object writer a chance to perform post-layout binding (for
794 // example, to set the index fields in the symbol data).
795 getWriter().executePostLayoutBinding(*this, Layout);
796
797 // Evaluate and apply the fixups, generating relocation entries as necessary.
798 for (MCSection &Sec : *this) {
799 for (MCFragment &Frag : Sec) {
800 // Data and relaxable fragments both have fixups. So only process
801 // those here.
802 // FIXME: Is there a better way to do this? MCEncodedFragmentWithFixups
803 // being templated makes this tricky.
804 if (isa<MCEncodedFragment>(&Frag) &&
805 isa<MCCompactEncodedInstFragment>(&Frag))
806 continue;
807 if (!isa<MCEncodedFragment>(&Frag) && !isa<MCCVDefRangeFragment>(&Frag))
808 continue;
809 ArrayRef<MCFixup> Fixups;
810 MutableArrayRef<char> Contents;
811 const MCSubtargetInfo *STI = nullptr;
812 if (auto *FragWithFixups = dyn_cast<MCDataFragment>(&Frag)) {
813 Fixups = FragWithFixups->getFixups();
814 Contents = FragWithFixups->getContents();
815 STI = FragWithFixups->getSubtargetInfo();
816 assert(!FragWithFixups->hasInstructions() || STI != nullptr)(static_cast <bool> (!FragWithFixups->hasInstructions
() || STI != nullptr) ? void (0) : __assert_fail ("!FragWithFixups->hasInstructions() || STI != nullptr"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 816, __extension__ __PRETTY_FUNCTION__))
;
817 } else if (auto *FragWithFixups = dyn_cast<MCRelaxableFragment>(&Frag)) {
818 Fixups = FragWithFixups->getFixups();
819 Contents = FragWithFixups->getContents();
820 STI = FragWithFixups->getSubtargetInfo();
821 assert(!FragWithFixups->hasInstructions() || STI != nullptr)(static_cast <bool> (!FragWithFixups->hasInstructions
() || STI != nullptr) ? void (0) : __assert_fail ("!FragWithFixups->hasInstructions() || STI != nullptr"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 821, __extension__ __PRETTY_FUNCTION__))
;
822 } else if (auto *FragWithFixups = dyn_cast<MCCVDefRangeFragment>(&Frag)) {
823 Fixups = FragWithFixups->getFixups();
824 Contents = FragWithFixups->getContents();
825 } else
826 llvm_unreachable("Unknown fragment with fixups!")::llvm::llvm_unreachable_internal("Unknown fragment with fixups!"
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 826)
;
827 for (const MCFixup &Fixup : Fixups) {
828 uint64_t FixedValue;
829 bool IsResolved;
830 MCValue Target;
831 std::tie(Target, FixedValue, IsResolved) =
832 handleFixup(Layout, Frag, Fixup);
833 getBackend().applyFixup(*this, Fixup, Target, Contents, FixedValue,
834 IsResolved, STI);
835 }
836 }
837 }
838}
839
840void MCAssembler::Finish() {
841 // Create the layout object.
842 MCAsmLayout Layout(*this);
843 layout(Layout);
844
845 // Write the object file.
846 stats::ObjectBytes += getWriter().writeObject(*this, Layout);
847}
848
849bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,
850 const MCRelaxableFragment *DF,
851 const MCAsmLayout &Layout) const {
852 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 852, __extension__ __PRETTY_FUNCTION__))
;
853 MCValue Target;
854 uint64_t Value;
855 bool WasForced;
856 bool Resolved = evaluateFixup(Layout, Fixup, DF, Target, Value, WasForced);
857 if (Target.getSymA() &&
858 Target.getSymA()->getKind() == MCSymbolRefExpr::VK_X86_ABS8 &&
859 Fixup.getKind() == FK_Data_1)
860 return false;
861 return getBackend().fixupNeedsRelaxationAdvanced(Fixup, Resolved, Value, DF,
862 Layout, WasForced);
863}
864
865bool MCAssembler::fragmentNeedsRelaxation(const MCRelaxableFragment *F,
866 const MCAsmLayout &Layout) const {
867 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 867, __extension__ __PRETTY_FUNCTION__))
;
868 // If this inst doesn't ever need relaxation, ignore it. This occurs when we
869 // are intentionally pushing out inst fragments, or because we relaxed a
870 // previous instruction to one that doesn't need relaxation.
871 if (!getBackend().mayNeedRelaxation(F->getInst(), *F->getSubtargetInfo()))
872 return false;
873
874 for (const MCFixup &Fixup : F->getFixups())
875 if (fixupNeedsRelaxation(Fixup, F, Layout))
876 return true;
877
878 return false;
879}
880
881bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
882 MCRelaxableFragment &F) {
883 assert(getEmitterPtr() &&(static_cast <bool> (getEmitterPtr() && "Expected CodeEmitter defined for relaxInstruction"
) ? void (0) : __assert_fail ("getEmitterPtr() && \"Expected CodeEmitter defined for relaxInstruction\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 884, __extension__ __PRETTY_FUNCTION__))
884 "Expected CodeEmitter defined for relaxInstruction")(static_cast <bool> (getEmitterPtr() && "Expected CodeEmitter defined for relaxInstruction"
) ? void (0) : __assert_fail ("getEmitterPtr() && \"Expected CodeEmitter defined for relaxInstruction\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 884, __extension__ __PRETTY_FUNCTION__))
;
885 if (!fragmentNeedsRelaxation(&F, Layout))
886 return false;
887
888 ++stats::RelaxedInstructions;
889
890 // FIXME-PERF: We could immediately lower out instructions if we can tell
891 // they are fully resolved, to avoid retesting on later passes.
892
893 // Relax the fragment.
894
895 MCInst Relaxed;
896 getBackend().relaxInstruction(F.getInst(), *F.getSubtargetInfo(), Relaxed);
897
898 // Encode the new instruction.
899 //
900 // FIXME-PERF: If it matters, we could let the target do this. It can
901 // probably do so more efficiently in many cases.
902 SmallVector<MCFixup, 4> Fixups;
903 SmallString<256> Code;
904 raw_svector_ostream VecOS(Code);
905 getEmitter().encodeInstruction(Relaxed, VecOS, Fixups, *F.getSubtargetInfo());
906
907 // Update the fragment.
908 F.setInst(Relaxed);
909 F.getContents() = Code;
910 F.getFixups() = Fixups;
911
912 return true;
913}
914
915bool MCAssembler::relaxPaddingFragment(MCAsmLayout &Layout,
916 MCPaddingFragment &PF) {
917 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 917, __extension__ __PRETTY_FUNCTION__))
;
918 uint64_t OldSize = PF.getSize();
919 if (!getBackend().relaxFragment(&PF, Layout))
920 return false;
921 uint64_t NewSize = PF.getSize();
922
923 ++stats::PaddingFragmentsRelaxations;
924 stats::PaddingFragmentsBytes += NewSize;
925 stats::PaddingFragmentsBytes -= OldSize;
926 return true;
927}
928
929bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
930 uint64_t OldSize = LF.getContents().size();
931 int64_t Value;
932 bool Abs = LF.getValue().evaluateKnownAbsolute(Value, Layout);
933 if (!Abs)
934 report_fatal_error("sleb128 and uleb128 expressions must be absolute");
935 SmallString<8> &Data = LF.getContents();
936 Data.clear();
937 raw_svector_ostream OSE(Data);
938 // The compiler can generate EH table assembly that is impossible to assemble
939 // without either adding padding to an LEB fragment or adding extra padding
940 // to a later alignment fragment. To accommodate such tables, relaxation can
941 // only increase an LEB fragment size here, not decrease it. See PR35809.
942 if (LF.isSigned())
943 encodeSLEB128(Value, OSE, OldSize);
944 else
945 encodeULEB128(Value, OSE, OldSize);
946 return OldSize != LF.getContents().size();
947}
948
949bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
950 MCDwarfLineAddrFragment &DF) {
951 MCContext &Context = Layout.getAssembler().getContext();
952 uint64_t OldSize = DF.getContents().size();
953 int64_t AddrDelta;
954 bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
955 assert(Abs && "We created a line delta with an invalid expression")(static_cast <bool> (Abs && "We created a line delta with an invalid expression"
) ? void (0) : __assert_fail ("Abs && \"We created a line delta with an invalid expression\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 955, __extension__ __PRETTY_FUNCTION__))
;
956 (void) Abs;
957 int64_t LineDelta;
958 LineDelta = DF.getLineDelta();
959 SmallString<8> &Data = DF.getContents();
960 Data.clear();
961 raw_svector_ostream OSE(Data);
962 MCDwarfLineAddr::Encode(Context, getDWARFLinetableParams(), LineDelta,
963 AddrDelta, OSE);
964 return OldSize != Data.size();
965}
966
967bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
968 MCDwarfCallFrameFragment &DF) {
969 MCContext &Context = Layout.getAssembler().getContext();
970 uint64_t OldSize = DF.getContents().size();
971 int64_t AddrDelta;
972 bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
973 assert(Abs && "We created call frame with an invalid expression")(static_cast <bool> (Abs && "We created call frame with an invalid expression"
) ? void (0) : __assert_fail ("Abs && \"We created call frame with an invalid expression\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 973, __extension__ __PRETTY_FUNCTION__))
;
974 (void) Abs;
975 SmallString<8> &Data = DF.getContents();
976 Data.clear();
977 raw_svector_ostream OSE(Data);
978 MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
979 return OldSize != Data.size();
980}
981
982bool MCAssembler::relaxCVInlineLineTable(MCAsmLayout &Layout,
983 MCCVInlineLineTableFragment &F) {
984 unsigned OldSize = F.getContents().size();
985 getContext().getCVContext().encodeInlineLineTable(Layout, F);
986 return OldSize != F.getContents().size();
987}
988
989bool MCAssembler::relaxCVDefRange(MCAsmLayout &Layout,
990 MCCVDefRangeFragment &F) {
991 unsigned OldSize = F.getContents().size();
992 getContext().getCVContext().encodeDefRange(Layout, F);
993 return OldSize != F.getContents().size();
994}
995
996bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec) {
997 // Holds the first fragment which needed relaxing during this layout. It will
998 // remain NULL if none were relaxed.
999 // When a fragment is relaxed, all the fragments following it should get
1000 // invalidated because their offset is going to change.
1001 MCFragment *FirstRelaxedFragment = nullptr;
1002
1003 // Attempt to relax all the fragments in the section.
1004 for (MCSection::iterator I = Sec.begin(), IE = Sec.end(); I != IE; ++I) {
1005 // Check if this is a fragment that needs relaxation.
1006 bool RelaxedFrag = false;
1007 switch(I->getKind()) {
1008 default:
1009 break;
1010 case MCFragment::FT_Relaxable:
1011 assert(!getRelaxAll() &&(static_cast <bool> (!getRelaxAll() && "Did not expect a MCRelaxableFragment in RelaxAll mode"
) ? void (0) : __assert_fail ("!getRelaxAll() && \"Did not expect a MCRelaxableFragment in RelaxAll mode\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 1012, __extension__ __PRETTY_FUNCTION__))
1012 "Did not expect a MCRelaxableFragment in RelaxAll mode")(static_cast <bool> (!getRelaxAll() && "Did not expect a MCRelaxableFragment in RelaxAll mode"
) ? void (0) : __assert_fail ("!getRelaxAll() && \"Did not expect a MCRelaxableFragment in RelaxAll mode\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 1012, __extension__ __PRETTY_FUNCTION__))
;
1013 RelaxedFrag = relaxInstruction(Layout, *cast<MCRelaxableFragment>(I));
1014 break;
1015 case MCFragment::FT_Dwarf:
1016 RelaxedFrag = relaxDwarfLineAddr(Layout,
1017 *cast<MCDwarfLineAddrFragment>(I));
1018 break;
1019 case MCFragment::FT_DwarfFrame:
1020 RelaxedFrag =
1021 relaxDwarfCallFrameFragment(Layout,
1022 *cast<MCDwarfCallFrameFragment>(I));
1023 break;
1024 case MCFragment::FT_LEB:
1025 RelaxedFrag = relaxLEB(Layout, *cast<MCLEBFragment>(I));
1026 break;
1027 case MCFragment::FT_Padding:
1028 RelaxedFrag = relaxPaddingFragment(Layout, *cast<MCPaddingFragment>(I));
1029 break;
1030 case MCFragment::FT_CVInlineLines:
1031 RelaxedFrag =
1032 relaxCVInlineLineTable(Layout, *cast<MCCVInlineLineTableFragment>(I));
1033 break;
1034 case MCFragment::FT_CVDefRange:
1035 RelaxedFrag = relaxCVDefRange(Layout, *cast<MCCVDefRangeFragment>(I));
1036 break;
1037 }
1038 if (RelaxedFrag && !FirstRelaxedFragment)
1039 FirstRelaxedFragment = &*I;
1040 }
1041 if (FirstRelaxedFragment) {
1042 Layout.invalidateFragmentsFrom(FirstRelaxedFragment);
1043 return true;
1044 }
1045 return false;
1046}
1047
1048bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
1049 ++stats::RelaxationSteps;
1050
1051 bool WasRelaxed = false;
1052 for (iterator it = begin(), ie = end(); it != ie; ++it) {
1053 MCSection &Sec = *it;
1054 while (layoutSectionOnce(Layout, Sec))
1055 WasRelaxed = true;
1056 }
1057
1058 return WasRelaxed;
1059}
1060
1061void MCAssembler::finishLayout(MCAsmLayout &Layout) {
1062 assert(getBackendPtr() && "Expected assembler backend")(static_cast <bool> (getBackendPtr() && "Expected assembler backend"
) ? void (0) : __assert_fail ("getBackendPtr() && \"Expected assembler backend\""
, "/build/llvm-toolchain-snapshot-7~svn338205/lib/MC/MCAssembler.cpp"
, 1062, __extension__ __PRETTY_FUNCTION__))
;
1063 // The layout is done. Mark every fragment as valid.
1064 for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
1065 MCSection &Section = *Layout.getSectionOrder()[i];
1066 Layout.getFragmentOffset(&*Section.rbegin());
1067 computeFragmentSize(Layout, *Section.rbegin());
1068 }
1069 getBackend().finishLayout(*this, Layout);
1070}
1071
1072#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1073LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void MCAssembler::dump() const{
1074 raw_ostream &OS = errs();
1075
1076 OS << "<MCAssembler\n";
1077 OS << " Sections:[\n ";
1078 for (const_iterator it = begin(), ie = end(); it != ie; ++it) {
1079 if (it != begin()) OS << ",\n ";
1080 it->dump();
1081 }
1082 OS << "],\n";
1083 OS << " Symbols:[";
1084
1085 for (const_symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
1086 if (it != symbol_begin()) OS << ",\n ";
1087 OS << "(";
1088 it->dump();
1089 OS << ", Index:" << it->getIndex() << ", ";
1090 OS << ")";
1091 }
1092 OS << "]>\n";
1093}
1094#endif