LLVM 18.0.0git
SafeStack.cpp
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1//===- SafeStack.cpp - Safe Stack Insertion -------------------------------===//
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 pass splits the stack into the safe stack (kept as-is for LLVM backend)
10// and the unsafe stack (explicitly allocated and managed through the runtime
11// support library).
12//
13// http://clang.llvm.org/docs/SafeStack.html
14//
15//===----------------------------------------------------------------------===//
16
17#include "SafeStackLayout.h"
18#include "llvm/ADT/APInt.h"
19#include "llvm/ADT/ArrayRef.h"
22#include "llvm/ADT/Statistic.h"
35#include "llvm/IR/Argument.h"
36#include "llvm/IR/Attributes.h"
38#include "llvm/IR/Constants.h"
39#include "llvm/IR/DIBuilder.h"
40#include "llvm/IR/DataLayout.h"
42#include "llvm/IR/Dominators.h"
43#include "llvm/IR/Function.h"
44#include "llvm/IR/IRBuilder.h"
46#include "llvm/IR/Instruction.h"
49#include "llvm/IR/Intrinsics.h"
50#include "llvm/IR/MDBuilder.h"
51#include "llvm/IR/Metadata.h"
52#include "llvm/IR/Module.h"
53#include "llvm/IR/Type.h"
54#include "llvm/IR/Use.h"
55#include "llvm/IR/Value.h"
57#include "llvm/Pass.h"
59#include "llvm/Support/Debug.h"
67#include <algorithm>
68#include <cassert>
69#include <cstdint>
70#include <optional>
71#include <string>
72#include <utility>
73
74using namespace llvm;
75using namespace llvm::safestack;
76
77#define DEBUG_TYPE "safe-stack"
78
79namespace llvm {
80
81STATISTIC(NumFunctions, "Total number of functions");
82STATISTIC(NumUnsafeStackFunctions, "Number of functions with unsafe stack");
83STATISTIC(NumUnsafeStackRestorePointsFunctions,
84 "Number of functions that use setjmp or exceptions");
85
86STATISTIC(NumAllocas, "Total number of allocas");
87STATISTIC(NumUnsafeStaticAllocas, "Number of unsafe static allocas");
88STATISTIC(NumUnsafeDynamicAllocas, "Number of unsafe dynamic allocas");
89STATISTIC(NumUnsafeByValArguments, "Number of unsafe byval arguments");
90STATISTIC(NumUnsafeStackRestorePoints, "Number of setjmps and landingpads");
91
92} // namespace llvm
93
94/// Use __safestack_pointer_address even if the platform has a faster way of
95/// access safe stack pointer.
96static cl::opt<bool>
97 SafeStackUsePointerAddress("safestack-use-pointer-address",
98 cl::init(false), cl::Hidden);
99
100static cl::opt<bool> ClColoring("safe-stack-coloring",
101 cl::desc("enable safe stack coloring"),
102 cl::Hidden, cl::init(true));
103
104namespace {
105
106/// The SafeStack pass splits the stack of each function into the safe
107/// stack, which is only accessed through memory safe dereferences (as
108/// determined statically), and the unsafe stack, which contains all
109/// local variables that are accessed in ways that we can't prove to
110/// be safe.
111class SafeStack {
112 Function &F;
113 const TargetLoweringBase &TL;
114 const DataLayout &DL;
115 DomTreeUpdater *DTU;
116 ScalarEvolution &SE;
117
118 Type *StackPtrTy;
119 Type *IntPtrTy;
120 Type *Int32Ty;
121 Type *Int8Ty;
122
123 Value *UnsafeStackPtr = nullptr;
124
125 /// Unsafe stack alignment. Each stack frame must ensure that the stack is
126 /// aligned to this value. We need to re-align the unsafe stack if the
127 /// alignment of any object on the stack exceeds this value.
128 ///
129 /// 16 seems like a reasonable upper bound on the alignment of objects that we
130 /// might expect to appear on the stack on most common targets.
131 static constexpr Align StackAlignment = Align::Constant<16>();
132
133 /// Return the value of the stack canary.
135
136 /// Load stack guard from the frame and check if it has changed.
137 void checkStackGuard(IRBuilder<> &IRB, Function &F, Instruction &RI,
138 AllocaInst *StackGuardSlot, Value *StackGuard);
139
140 /// Find all static allocas, dynamic allocas, return instructions and
141 /// stack restore points (exception unwind blocks and setjmp calls) in the
142 /// given function and append them to the respective vectors.
143 void findInsts(Function &F, SmallVectorImpl<AllocaInst *> &StaticAllocas,
144 SmallVectorImpl<AllocaInst *> &DynamicAllocas,
145 SmallVectorImpl<Argument *> &ByValArguments,
147 SmallVectorImpl<Instruction *> &StackRestorePoints);
148
149 /// Calculate the allocation size of a given alloca. Returns 0 if the
150 /// size can not be statically determined.
151 uint64_t getStaticAllocaAllocationSize(const AllocaInst* AI);
152
153 /// Allocate space for all static allocas in \p StaticAllocas,
154 /// replace allocas with pointers into the unsafe stack.
155 ///
156 /// \returns A pointer to the top of the unsafe stack after all unsafe static
157 /// allocas are allocated.
158 Value *moveStaticAllocasToUnsafeStack(IRBuilder<> &IRB, Function &F,
159 ArrayRef<AllocaInst *> StaticAllocas,
160 ArrayRef<Argument *> ByValArguments,
161 Instruction *BasePointer,
162 AllocaInst *StackGuardSlot);
163
164 /// Generate code to restore the stack after all stack restore points
165 /// in \p StackRestorePoints.
166 ///
167 /// \returns A local variable in which to maintain the dynamic top of the
168 /// unsafe stack if needed.
169 AllocaInst *
170 createStackRestorePoints(IRBuilder<> &IRB, Function &F,
171 ArrayRef<Instruction *> StackRestorePoints,
172 Value *StaticTop, bool NeedDynamicTop);
173
174 /// Replace all allocas in \p DynamicAllocas with code to allocate
175 /// space dynamically on the unsafe stack and store the dynamic unsafe stack
176 /// top to \p DynamicTop if non-null.
177 void moveDynamicAllocasToUnsafeStack(Function &F, Value *UnsafeStackPtr,
178 AllocaInst *DynamicTop,
179 ArrayRef<AllocaInst *> DynamicAllocas);
180
181 bool IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize);
182
183 bool IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
184 const Value *AllocaPtr, uint64_t AllocaSize);
185 bool IsAccessSafe(Value *Addr, uint64_t Size, const Value *AllocaPtr,
186 uint64_t AllocaSize);
187
188 bool ShouldInlinePointerAddress(CallInst &CI);
189 void TryInlinePointerAddress();
190
191public:
192 SafeStack(Function &F, const TargetLoweringBase &TL, const DataLayout &DL,
194 : F(F), TL(TL), DL(DL), DTU(DTU), SE(SE),
195 StackPtrTy(PointerType::getUnqual(F.getContext())),
196 IntPtrTy(DL.getIntPtrType(F.getContext())),
197 Int32Ty(Type::getInt32Ty(F.getContext())),
198 Int8Ty(Type::getInt8Ty(F.getContext())) {}
199
200 // Run the transformation on the associated function.
201 // Returns whether the function was changed.
202 bool run();
203};
204
205constexpr Align SafeStack::StackAlignment;
206
207uint64_t SafeStack::getStaticAllocaAllocationSize(const AllocaInst* AI) {
208 uint64_t Size = DL.getTypeAllocSize(AI->getAllocatedType());
209 if (AI->isArrayAllocation()) {
210 auto C = dyn_cast<ConstantInt>(AI->getArraySize());
211 if (!C)
212 return 0;
213 Size *= C->getZExtValue();
214 }
215 return Size;
216}
217
218bool SafeStack::IsAccessSafe(Value *Addr, uint64_t AccessSize,
219 const Value *AllocaPtr, uint64_t AllocaSize) {
220 const SCEV *AddrExpr = SE.getSCEV(Addr);
221 const auto *Base = dyn_cast<SCEVUnknown>(SE.getPointerBase(AddrExpr));
222 if (!Base || Base->getValue() != AllocaPtr) {
224 dbgs() << "[SafeStack] "
225 << (isa<AllocaInst>(AllocaPtr) ? "Alloca " : "ByValArgument ")
226 << *AllocaPtr << "\n"
227 << "SCEV " << *AddrExpr << " not directly based on alloca\n");
228 return false;
229 }
230
231 const SCEV *Expr = SE.removePointerBase(AddrExpr);
232 uint64_t BitWidth = SE.getTypeSizeInBits(Expr->getType());
233 ConstantRange AccessStartRange = SE.getUnsignedRange(Expr);
234 ConstantRange SizeRange =
235 ConstantRange(APInt(BitWidth, 0), APInt(BitWidth, AccessSize));
236 ConstantRange AccessRange = AccessStartRange.add(SizeRange);
237 ConstantRange AllocaRange =
238 ConstantRange(APInt(BitWidth, 0), APInt(BitWidth, AllocaSize));
239 bool Safe = AllocaRange.contains(AccessRange);
240
242 dbgs() << "[SafeStack] "
243 << (isa<AllocaInst>(AllocaPtr) ? "Alloca " : "ByValArgument ")
244 << *AllocaPtr << "\n"
245 << " Access " << *Addr << "\n"
246 << " SCEV " << *Expr
247 << " U: " << SE.getUnsignedRange(Expr)
248 << ", S: " << SE.getSignedRange(Expr) << "\n"
249 << " Range " << AccessRange << "\n"
250 << " AllocaRange " << AllocaRange << "\n"
251 << " " << (Safe ? "safe" : "unsafe") << "\n");
252
253 return Safe;
254}
255
256bool SafeStack::IsMemIntrinsicSafe(const MemIntrinsic *MI, const Use &U,
257 const Value *AllocaPtr,
258 uint64_t AllocaSize) {
259 if (auto MTI = dyn_cast<MemTransferInst>(MI)) {
260 if (MTI->getRawSource() != U && MTI->getRawDest() != U)
261 return true;
262 } else {
263 if (MI->getRawDest() != U)
264 return true;
265 }
266
267 const auto *Len = dyn_cast<ConstantInt>(MI->getLength());
268 // Non-constant size => unsafe. FIXME: try SCEV getRange.
269 if (!Len) return false;
270 return IsAccessSafe(U, Len->getZExtValue(), AllocaPtr, AllocaSize);
271}
272
273/// Check whether a given allocation must be put on the safe
274/// stack or not. The function analyzes all uses of AI and checks whether it is
275/// only accessed in a memory safe way (as decided statically).
276bool SafeStack::IsSafeStackAlloca(const Value *AllocaPtr, uint64_t AllocaSize) {
277 // Go through all uses of this alloca and check whether all accesses to the
278 // allocated object are statically known to be memory safe and, hence, the
279 // object can be placed on the safe stack.
282 WorkList.push_back(AllocaPtr);
283
284 // A DFS search through all uses of the alloca in bitcasts/PHI/GEPs/etc.
285 while (!WorkList.empty()) {
286 const Value *V = WorkList.pop_back_val();
287 for (const Use &UI : V->uses()) {
288 auto I = cast<const Instruction>(UI.getUser());
289 assert(V == UI.get());
290
291 switch (I->getOpcode()) {
292 case Instruction::Load:
293 if (!IsAccessSafe(UI, DL.getTypeStoreSize(I->getType()), AllocaPtr,
294 AllocaSize))
295 return false;
296 break;
297
298 case Instruction::VAArg:
299 // "va-arg" from a pointer is safe.
300 break;
301 case Instruction::Store:
302 if (V == I->getOperand(0)) {
303 // Stored the pointer - conservatively assume it may be unsafe.
305 << "[SafeStack] Unsafe alloca: " << *AllocaPtr
306 << "\n store of address: " << *I << "\n");
307 return false;
308 }
309
310 if (!IsAccessSafe(UI, DL.getTypeStoreSize(I->getOperand(0)->getType()),
311 AllocaPtr, AllocaSize))
312 return false;
313 break;
314
315 case Instruction::Ret:
316 // Information leak.
317 return false;
318
319 case Instruction::Call:
320 case Instruction::Invoke: {
321 const CallBase &CS = *cast<CallBase>(I);
322
323 if (I->isLifetimeStartOrEnd())
324 continue;
325
326 if (const MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) {
327 if (!IsMemIntrinsicSafe(MI, UI, AllocaPtr, AllocaSize)) {
329 << "[SafeStack] Unsafe alloca: " << *AllocaPtr
330 << "\n unsafe memintrinsic: " << *I << "\n");
331 return false;
332 }
333 continue;
334 }
335
336 // LLVM 'nocapture' attribute is only set for arguments whose address
337 // is not stored, passed around, or used in any other non-trivial way.
338 // We assume that passing a pointer to an object as a 'nocapture
339 // readnone' argument is safe.
340 // FIXME: a more precise solution would require an interprocedural
341 // analysis here, which would look at all uses of an argument inside
342 // the function being called.
343 auto B = CS.arg_begin(), E = CS.arg_end();
344 for (const auto *A = B; A != E; ++A)
345 if (A->get() == V)
346 if (!(CS.doesNotCapture(A - B) && (CS.doesNotAccessMemory(A - B) ||
347 CS.doesNotAccessMemory()))) {
348 LLVM_DEBUG(dbgs() << "[SafeStack] Unsafe alloca: " << *AllocaPtr
349 << "\n unsafe call: " << *I << "\n");
350 return false;
351 }
352 continue;
353 }
354
355 default:
356 if (Visited.insert(I).second)
357 WorkList.push_back(cast<const Instruction>(I));
358 }
359 }
360 }
361
362 // All uses of the alloca are safe, we can place it on the safe stack.
363 return true;
364}
365
366Value *SafeStack::getStackGuard(IRBuilder<> &IRB, Function &F) {
367 Value *StackGuardVar = TL.getIRStackGuard(IRB);
368 Module *M = F.getParent();
369
370 if (!StackGuardVar) {
371 TL.insertSSPDeclarations(*M);
372 return IRB.CreateCall(Intrinsic::getDeclaration(M, Intrinsic::stackguard));
373 }
374
375 return IRB.CreateLoad(StackPtrTy, StackGuardVar, "StackGuard");
376}
377
378void SafeStack::findInsts(Function &F,
379 SmallVectorImpl<AllocaInst *> &StaticAllocas,
380 SmallVectorImpl<AllocaInst *> &DynamicAllocas,
381 SmallVectorImpl<Argument *> &ByValArguments,
383 SmallVectorImpl<Instruction *> &StackRestorePoints) {
384 for (Instruction &I : instructions(&F)) {
385 if (auto AI = dyn_cast<AllocaInst>(&I)) {
386 ++NumAllocas;
387
388 uint64_t Size = getStaticAllocaAllocationSize(AI);
389 if (IsSafeStackAlloca(AI, Size))
390 continue;
391
392 if (AI->isStaticAlloca()) {
393 ++NumUnsafeStaticAllocas;
394 StaticAllocas.push_back(AI);
395 } else {
396 ++NumUnsafeDynamicAllocas;
397 DynamicAllocas.push_back(AI);
398 }
399 } else if (auto RI = dyn_cast<ReturnInst>(&I)) {
400 if (CallInst *CI = I.getParent()->getTerminatingMustTailCall())
401 Returns.push_back(CI);
402 else
403 Returns.push_back(RI);
404 } else if (auto CI = dyn_cast<CallInst>(&I)) {
405 // setjmps require stack restore.
406 if (CI->getCalledFunction() && CI->canReturnTwice())
407 StackRestorePoints.push_back(CI);
408 } else if (auto LP = dyn_cast<LandingPadInst>(&I)) {
409 // Exception landing pads require stack restore.
410 StackRestorePoints.push_back(LP);
411 } else if (auto II = dyn_cast<IntrinsicInst>(&I)) {
412 if (II->getIntrinsicID() == Intrinsic::gcroot)
414 "gcroot intrinsic not compatible with safestack attribute");
415 }
416 }
417 for (Argument &Arg : F.args()) {
418 if (!Arg.hasByValAttr())
419 continue;
420 uint64_t Size = DL.getTypeStoreSize(Arg.getParamByValType());
421 if (IsSafeStackAlloca(&Arg, Size))
422 continue;
423
424 ++NumUnsafeByValArguments;
425 ByValArguments.push_back(&Arg);
426 }
427}
428
430SafeStack::createStackRestorePoints(IRBuilder<> &IRB, Function &F,
431 ArrayRef<Instruction *> StackRestorePoints,
432 Value *StaticTop, bool NeedDynamicTop) {
433 assert(StaticTop && "The stack top isn't set.");
434
435 if (StackRestorePoints.empty())
436 return nullptr;
437
438 // We need the current value of the shadow stack pointer to restore
439 // after longjmp or exception catching.
440
441 // FIXME: On some platforms this could be handled by the longjmp/exception
442 // runtime itself.
443
444 AllocaInst *DynamicTop = nullptr;
445 if (NeedDynamicTop) {
446 // If we also have dynamic alloca's, the stack pointer value changes
447 // throughout the function. For now we store it in an alloca.
448 DynamicTop = IRB.CreateAlloca(StackPtrTy, /*ArraySize=*/nullptr,
449 "unsafe_stack_dynamic_ptr");
450 IRB.CreateStore(StaticTop, DynamicTop);
451 }
452
453 // Restore current stack pointer after longjmp/exception catch.
454 for (Instruction *I : StackRestorePoints) {
455 ++NumUnsafeStackRestorePoints;
456
457 IRB.SetInsertPoint(I->getNextNode());
458 Value *CurrentTop =
459 DynamicTop ? IRB.CreateLoad(StackPtrTy, DynamicTop) : StaticTop;
460 IRB.CreateStore(CurrentTop, UnsafeStackPtr);
461 }
462
463 return DynamicTop;
464}
465
466void SafeStack::checkStackGuard(IRBuilder<> &IRB, Function &F, Instruction &RI,
467 AllocaInst *StackGuardSlot, Value *StackGuard) {
468 Value *V = IRB.CreateLoad(StackPtrTy, StackGuardSlot);
469 Value *Cmp = IRB.CreateICmpNE(StackGuard, V);
470
473 MDNode *Weights = MDBuilder(F.getContext())
474 .createBranchWeights(SuccessProb.getNumerator(),
475 FailureProb.getNumerator());
476 Instruction *CheckTerm =
477 SplitBlockAndInsertIfThen(Cmp, &RI, /* Unreachable */ true, Weights, DTU);
478 IRBuilder<> IRBFail(CheckTerm);
479 // FIXME: respect -fsanitize-trap / -ftrap-function here?
480 FunctionCallee StackChkFail =
481 F.getParent()->getOrInsertFunction("__stack_chk_fail", IRB.getVoidTy());
482 IRBFail.CreateCall(StackChkFail, {});
483}
484
485/// We explicitly compute and set the unsafe stack layout for all unsafe
486/// static alloca instructions. We save the unsafe "base pointer" in the
487/// prologue into a local variable and restore it in the epilogue.
488Value *SafeStack::moveStaticAllocasToUnsafeStack(
489 IRBuilder<> &IRB, Function &F, ArrayRef<AllocaInst *> StaticAllocas,
490 ArrayRef<Argument *> ByValArguments, Instruction *BasePointer,
491 AllocaInst *StackGuardSlot) {
492 if (StaticAllocas.empty() && ByValArguments.empty())
493 return BasePointer;
494
495 DIBuilder DIB(*F.getParent());
496
497 StackLifetime SSC(F, StaticAllocas, StackLifetime::LivenessType::May);
498 static const StackLifetime::LiveRange NoColoringRange(1, true);
499 if (ClColoring)
500 SSC.run();
501
502 for (const auto *I : SSC.getMarkers()) {
503 auto *Op = dyn_cast<Instruction>(I->getOperand(1));
504 const_cast<IntrinsicInst *>(I)->eraseFromParent();
505 // Remove the operand bitcast, too, if it has no more uses left.
506 if (Op && Op->use_empty())
507 Op->eraseFromParent();
508 }
509
510 // Unsafe stack always grows down.
511 StackLayout SSL(StackAlignment);
512 if (StackGuardSlot) {
513 Type *Ty = StackGuardSlot->getAllocatedType();
514 Align Align = std::max(DL.getPrefTypeAlign(Ty), StackGuardSlot->getAlign());
515 SSL.addObject(StackGuardSlot, getStaticAllocaAllocationSize(StackGuardSlot),
516 Align, SSC.getFullLiveRange());
517 }
518
519 for (Argument *Arg : ByValArguments) {
520 Type *Ty = Arg->getParamByValType();
521 uint64_t Size = DL.getTypeStoreSize(Ty);
522 if (Size == 0)
523 Size = 1; // Don't create zero-sized stack objects.
524
525 // Ensure the object is properly aligned.
526 Align Align = DL.getPrefTypeAlign(Ty);
527 if (auto A = Arg->getParamAlign())
528 Align = std::max(Align, *A);
529 SSL.addObject(Arg, Size, Align, SSC.getFullLiveRange());
530 }
531
532 for (AllocaInst *AI : StaticAllocas) {
533 Type *Ty = AI->getAllocatedType();
534 uint64_t Size = getStaticAllocaAllocationSize(AI);
535 if (Size == 0)
536 Size = 1; // Don't create zero-sized stack objects.
537
538 // Ensure the object is properly aligned.
539 Align Align = std::max(DL.getPrefTypeAlign(Ty), AI->getAlign());
540
541 SSL.addObject(AI, Size, Align,
542 ClColoring ? SSC.getLiveRange(AI) : NoColoringRange);
543 }
544
545 SSL.computeLayout();
546 Align FrameAlignment = SSL.getFrameAlignment();
547
548 // FIXME: tell SSL that we start at a less-then-MaxAlignment aligned location
549 // (AlignmentSkew).
550 if (FrameAlignment > StackAlignment) {
551 // Re-align the base pointer according to the max requested alignment.
552 IRB.SetInsertPoint(BasePointer->getNextNode());
553 BasePointer = cast<Instruction>(IRB.CreateIntToPtr(
554 IRB.CreateAnd(
555 IRB.CreatePtrToInt(BasePointer, IntPtrTy),
556 ConstantInt::get(IntPtrTy, ~(FrameAlignment.value() - 1))),
557 StackPtrTy));
558 }
559
560 IRB.SetInsertPoint(BasePointer->getNextNode());
561
562 if (StackGuardSlot) {
563 unsigned Offset = SSL.getObjectOffset(StackGuardSlot);
564 Value *Off = IRB.CreateGEP(Int8Ty, BasePointer, // BasePointer is i8*
566 Value *NewAI =
567 IRB.CreateBitCast(Off, StackGuardSlot->getType(), "StackGuardSlot");
568
569 // Replace alloc with the new location.
570 StackGuardSlot->replaceAllUsesWith(NewAI);
571 StackGuardSlot->eraseFromParent();
572 }
573
574 for (Argument *Arg : ByValArguments) {
575 unsigned Offset = SSL.getObjectOffset(Arg);
576 MaybeAlign Align(SSL.getObjectAlignment(Arg));
577 Type *Ty = Arg->getParamByValType();
578
579 uint64_t Size = DL.getTypeStoreSize(Ty);
580 if (Size == 0)
581 Size = 1; // Don't create zero-sized stack objects.
582
583 Value *Off = IRB.CreateGEP(Int8Ty, BasePointer, // BasePointer is i8*
585 Value *NewArg = IRB.CreateBitCast(Off, Arg->getType(),
586 Arg->getName() + ".unsafe-byval");
587
588 // Replace alloc with the new location.
589 replaceDbgDeclare(Arg, BasePointer, DIB, DIExpression::ApplyOffset,
590 -Offset);
591 Arg->replaceAllUsesWith(NewArg);
592 IRB.SetInsertPoint(cast<Instruction>(NewArg)->getNextNode());
593 IRB.CreateMemCpy(Off, Align, Arg, Arg->getParamAlign(), Size);
594 }
595
596 // Allocate space for every unsafe static AllocaInst on the unsafe stack.
597 for (AllocaInst *AI : StaticAllocas) {
598 IRB.SetInsertPoint(AI);
599 unsigned Offset = SSL.getObjectOffset(AI);
600
601 replaceDbgDeclare(AI, BasePointer, DIB, DIExpression::ApplyOffset, -Offset);
602 replaceDbgValueForAlloca(AI, BasePointer, DIB, -Offset);
603
604 // Replace uses of the alloca with the new location.
605 // Insert address calculation close to each use to work around PR27844.
606 std::string Name = std::string(AI->getName()) + ".unsafe";
607 while (!AI->use_empty()) {
608 Use &U = *AI->use_begin();
609 Instruction *User = cast<Instruction>(U.getUser());
610
611 Instruction *InsertBefore;
612 if (auto *PHI = dyn_cast<PHINode>(User))
613 InsertBefore = PHI->getIncomingBlock(U)->getTerminator();
614 else
615 InsertBefore = User;
616
617 IRBuilder<> IRBUser(InsertBefore);
618 Value *Off = IRBUser.CreateGEP(Int8Ty, BasePointer, // BasePointer is i8*
620 Value *Replacement = IRBUser.CreateBitCast(Off, AI->getType(), Name);
621
622 if (auto *PHI = dyn_cast<PHINode>(User))
623 // PHI nodes may have multiple incoming edges from the same BB (why??),
624 // all must be updated at once with the same incoming value.
625 PHI->setIncomingValueForBlock(PHI->getIncomingBlock(U), Replacement);
626 else
627 U.set(Replacement);
628 }
629
630 AI->eraseFromParent();
631 }
632
633 // Re-align BasePointer so that our callees would see it aligned as
634 // expected.
635 // FIXME: no need to update BasePointer in leaf functions.
636 unsigned FrameSize = alignTo(SSL.getFrameSize(), StackAlignment);
637
638 MDBuilder MDB(F.getContext());
640 Data.push_back(MDB.createString("unsafe-stack-size"));
641 Data.push_back(MDB.createConstant(ConstantInt::get(Int32Ty, FrameSize)));
642 MDNode *MD = MDTuple::get(F.getContext(), Data);
643 F.setMetadata(LLVMContext::MD_annotation, MD);
644
645 // Update shadow stack pointer in the function epilogue.
646 IRB.SetInsertPoint(BasePointer->getNextNode());
647
648 Value *StaticTop =
649 IRB.CreateGEP(Int8Ty, BasePointer, ConstantInt::get(Int32Ty, -FrameSize),
650 "unsafe_stack_static_top");
651 IRB.CreateStore(StaticTop, UnsafeStackPtr);
652 return StaticTop;
653}
654
655void SafeStack::moveDynamicAllocasToUnsafeStack(
656 Function &F, Value *UnsafeStackPtr, AllocaInst *DynamicTop,
657 ArrayRef<AllocaInst *> DynamicAllocas) {
658 DIBuilder DIB(*F.getParent());
659
660 for (AllocaInst *AI : DynamicAllocas) {
661 IRBuilder<> IRB(AI);
662
663 // Compute the new SP value (after AI).
664 Value *ArraySize = AI->getArraySize();
665 if (ArraySize->getType() != IntPtrTy)
666 ArraySize = IRB.CreateIntCast(ArraySize, IntPtrTy, false);
667
668 Type *Ty = AI->getAllocatedType();
669 uint64_t TySize = DL.getTypeAllocSize(Ty);
670 Value *Size = IRB.CreateMul(ArraySize, ConstantInt::get(IntPtrTy, TySize));
671
672 Value *SP = IRB.CreatePtrToInt(IRB.CreateLoad(StackPtrTy, UnsafeStackPtr),
673 IntPtrTy);
674 SP = IRB.CreateSub(SP, Size);
675
676 // Align the SP value to satisfy the AllocaInst, type and stack alignments.
677 auto Align = std::max(std::max(DL.getPrefTypeAlign(Ty), AI->getAlign()),
678 StackAlignment);
679
680 Value *NewTop = IRB.CreateIntToPtr(
681 IRB.CreateAnd(SP,
682 ConstantInt::get(IntPtrTy, ~uint64_t(Align.value() - 1))),
683 StackPtrTy);
684
685 // Save the stack pointer.
686 IRB.CreateStore(NewTop, UnsafeStackPtr);
687 if (DynamicTop)
688 IRB.CreateStore(NewTop, DynamicTop);
689
690 Value *NewAI = IRB.CreatePointerCast(NewTop, AI->getType());
691 if (AI->hasName() && isa<Instruction>(NewAI))
692 NewAI->takeName(AI);
693
695 AI->replaceAllUsesWith(NewAI);
696 AI->eraseFromParent();
697 }
698
699 if (!DynamicAllocas.empty()) {
700 // Now go through the instructions again, replacing stacksave/stackrestore.
702 auto *II = dyn_cast<IntrinsicInst>(&I);
703 if (!II)
704 continue;
705
706 if (II->getIntrinsicID() == Intrinsic::stacksave) {
707 IRBuilder<> IRB(II);
708 Instruction *LI = IRB.CreateLoad(StackPtrTy, UnsafeStackPtr);
709 LI->takeName(II);
710 II->replaceAllUsesWith(LI);
711 II->eraseFromParent();
712 } else if (II->getIntrinsicID() == Intrinsic::stackrestore) {
713 IRBuilder<> IRB(II);
714 Instruction *SI = IRB.CreateStore(II->getArgOperand(0), UnsafeStackPtr);
715 SI->takeName(II);
716 assert(II->use_empty());
717 II->eraseFromParent();
718 }
719 }
720 }
721}
722
723bool SafeStack::ShouldInlinePointerAddress(CallInst &CI) {
725 if (CI.hasFnAttr(Attribute::AlwaysInline) &&
726 isInlineViable(*Callee).isSuccess())
727 return true;
728 if (Callee->isInterposable() || Callee->hasFnAttribute(Attribute::NoInline) ||
729 CI.isNoInline())
730 return false;
731 return true;
732}
733
734void SafeStack::TryInlinePointerAddress() {
735 auto *CI = dyn_cast<CallInst>(UnsafeStackPtr);
736 if (!CI)
737 return;
738
739 if(F.hasOptNone())
740 return;
741
743 if (!Callee || Callee->isDeclaration())
744 return;
745
746 if (!ShouldInlinePointerAddress(*CI))
747 return;
748
750 InlineFunction(*CI, IFI);
751}
752
753bool SafeStack::run() {
754 assert(F.hasFnAttribute(Attribute::SafeStack) &&
755 "Can't run SafeStack on a function without the attribute");
756 assert(!F.isDeclaration() && "Can't run SafeStack on a function declaration");
757
758 ++NumFunctions;
759
760 SmallVector<AllocaInst *, 16> StaticAllocas;
761 SmallVector<AllocaInst *, 4> DynamicAllocas;
762 SmallVector<Argument *, 4> ByValArguments;
764
765 // Collect all points where stack gets unwound and needs to be restored
766 // This is only necessary because the runtime (setjmp and unwind code) is
767 // not aware of the unsafe stack and won't unwind/restore it properly.
768 // To work around this problem without changing the runtime, we insert
769 // instrumentation to restore the unsafe stack pointer when necessary.
770 SmallVector<Instruction *, 4> StackRestorePoints;
771
772 // Find all static and dynamic alloca instructions that must be moved to the
773 // unsafe stack, all return instructions and stack restore points.
774 findInsts(F, StaticAllocas, DynamicAllocas, ByValArguments, Returns,
775 StackRestorePoints);
776
777 if (StaticAllocas.empty() && DynamicAllocas.empty() &&
778 ByValArguments.empty() && StackRestorePoints.empty())
779 return false; // Nothing to do in this function.
780
781 if (!StaticAllocas.empty() || !DynamicAllocas.empty() ||
782 !ByValArguments.empty())
783 ++NumUnsafeStackFunctions; // This function has the unsafe stack.
784
785 if (!StackRestorePoints.empty())
786 ++NumUnsafeStackRestorePointsFunctions;
787
788 IRBuilder<> IRB(&F.front(), F.begin()->getFirstInsertionPt());
789 // Calls must always have a debug location, or else inlining breaks. So
790 // we explicitly set a artificial debug location here.
791 if (DISubprogram *SP = F.getSubprogram())
793 DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP));
795 FunctionCallee Fn = F.getParent()->getOrInsertFunction(
796 "__safestack_pointer_address", StackPtrTy->getPointerTo(0));
797 UnsafeStackPtr = IRB.CreateCall(Fn);
798 } else {
799 UnsafeStackPtr = TL.getSafeStackPointerLocation(IRB);
800 }
801
802 // Load the current stack pointer (we'll also use it as a base pointer).
803 // FIXME: use a dedicated register for it ?
804 Instruction *BasePointer =
805 IRB.CreateLoad(StackPtrTy, UnsafeStackPtr, false, "unsafe_stack_ptr");
806 assert(BasePointer->getType() == StackPtrTy);
807
808 AllocaInst *StackGuardSlot = nullptr;
809 // FIXME: implement weaker forms of stack protector.
810 if (F.hasFnAttribute(Attribute::StackProtect) ||
811 F.hasFnAttribute(Attribute::StackProtectStrong) ||
812 F.hasFnAttribute(Attribute::StackProtectReq)) {
813 Value *StackGuard = getStackGuard(IRB, F);
814 StackGuardSlot = IRB.CreateAlloca(StackPtrTy, nullptr);
815 IRB.CreateStore(StackGuard, StackGuardSlot);
816
817 for (Instruction *RI : Returns) {
818 IRBuilder<> IRBRet(RI);
819 checkStackGuard(IRBRet, F, *RI, StackGuardSlot, StackGuard);
820 }
821 }
822
823 // The top of the unsafe stack after all unsafe static allocas are
824 // allocated.
825 Value *StaticTop = moveStaticAllocasToUnsafeStack(
826 IRB, F, StaticAllocas, ByValArguments, BasePointer, StackGuardSlot);
827
828 // Safe stack object that stores the current unsafe stack top. It is updated
829 // as unsafe dynamic (non-constant-sized) allocas are allocated and freed.
830 // This is only needed if we need to restore stack pointer after longjmp
831 // or exceptions, and we have dynamic allocations.
832 // FIXME: a better alternative might be to store the unsafe stack pointer
833 // before setjmp / invoke instructions.
834 AllocaInst *DynamicTop = createStackRestorePoints(
835 IRB, F, StackRestorePoints, StaticTop, !DynamicAllocas.empty());
836
837 // Handle dynamic allocas.
838 moveDynamicAllocasToUnsafeStack(F, UnsafeStackPtr, DynamicTop,
839 DynamicAllocas);
840
841 // Restore the unsafe stack pointer before each return.
842 for (Instruction *RI : Returns) {
843 IRB.SetInsertPoint(RI);
844 IRB.CreateStore(BasePointer, UnsafeStackPtr);
845 }
846
847 TryInlinePointerAddress();
848
849 LLVM_DEBUG(dbgs() << "[SafeStack] safestack applied\n");
850 return true;
851}
852
853class SafeStackLegacyPass : public FunctionPass {
854 const TargetMachine *TM = nullptr;
855
856public:
857 static char ID; // Pass identification, replacement for typeid..
858
859 SafeStackLegacyPass() : FunctionPass(ID) {
861 }
862
863 void getAnalysisUsage(AnalysisUsage &AU) const override {
868 }
869
870 bool runOnFunction(Function &F) override {
871 LLVM_DEBUG(dbgs() << "[SafeStack] Function: " << F.getName() << "\n");
872
873 if (!F.hasFnAttribute(Attribute::SafeStack)) {
874 LLVM_DEBUG(dbgs() << "[SafeStack] safestack is not requested"
875 " for this function\n");
876 return false;
877 }
878
879 if (F.isDeclaration()) {
880 LLVM_DEBUG(dbgs() << "[SafeStack] function definition"
881 " is not available\n");
882 return false;
883 }
884
885 TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
886 auto *TL = TM->getSubtargetImpl(F)->getTargetLowering();
887 if (!TL)
888 report_fatal_error("TargetLowering instance is required");
889
890 auto *DL = &F.getParent()->getDataLayout();
891 auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
892 auto &ACT = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
893
894 // Compute DT and LI only for functions that have the attribute.
895 // This is only useful because the legacy pass manager doesn't let us
896 // compute analyzes lazily.
897
898 DominatorTree *DT;
899 bool ShouldPreserveDominatorTree;
900 std::optional<DominatorTree> LazilyComputedDomTree;
901
902 // Do we already have a DominatorTree avaliable from the previous pass?
903 // Note that we should *NOT* require it, to avoid the case where we end up
904 // not needing it, but the legacy PM would have computed it for us anyways.
905 if (auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
906 DT = &DTWP->getDomTree();
907 ShouldPreserveDominatorTree = true;
908 } else {
909 // Otherwise, we need to compute it.
910 LazilyComputedDomTree.emplace(F);
911 DT = &*LazilyComputedDomTree;
912 ShouldPreserveDominatorTree = false;
913 }
914
915 // Likewise, lazily compute loop info.
916 LoopInfo LI(*DT);
917
918 DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
919
920 ScalarEvolution SE(F, TLI, ACT, *DT, LI);
921
922 return SafeStack(F, *TL, *DL, ShouldPreserveDominatorTree ? &DTU : nullptr,
923 SE)
924 .run();
925 }
926};
927
928} // end anonymous namespace
929
930char SafeStackLegacyPass::ID = 0;
931
933 "Safe Stack instrumentation pass", false, false)
936INITIALIZE_PASS_END(SafeStackLegacyPass, DEBUG_TYPE,
938
939FunctionPass *llvm::createSafeStackPass() { return new SafeStackLegacyPass(); }
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
Rewrite undef for PHI
This file implements a class to represent arbitrary precision integral constant values and operations...
This file contains the simple types necessary to represent the attributes associated with functions a...
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This file contains the declarations for the subclasses of Constant, which represent the different fla...
#define LLVM_DEBUG(X)
Definition: Debug.h:101
uint64_t Addr
std::string Name
uint64_t Size
IRTranslator LLVM IR MI
Select target instructions out of generic instructions
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
This file contains the declarations for metadata subclasses.
Module.h This file contains the declarations for the Module class.
IntegerType * Int32Ty
const char LLVMTargetMachineRef TM
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:55
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:59
#define INITIALIZE_PASS_BEGIN(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:52
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static cl::opt< bool > SafeStackUsePointerAddress("safestack-use-pointer-address", cl::init(false), cl::Hidden)
Use __safestack_pointer_address even if the platform has a faster way of access safe stack pointer.
static cl::opt< bool > ClColoring("safe-stack-coloring", cl::desc("enable safe stack coloring"), cl::Hidden, cl::init(true))
#define DEBUG_TYPE
Definition: SafeStack.cpp:77
Safe Stack instrumentation pass
Definition: SafeStack.cpp:937
This file defines the SmallPtrSet class.
This file defines the SmallVector class.
static Value * getStackGuard(const TargetLoweringBase *TLI, Module *M, IRBuilder<> &B, bool *SupportsSelectionDAGSP=nullptr)
Create a stack guard loading and populate whether SelectionDAG SSP is supported.
This file defines the 'Statistic' class, which is designed to be an easy way to expose various metric...
#define STATISTIC(VARNAME, DESC)
Definition: Statistic.h:167
This file describes how to lower LLVM code to machine code.
Target-Independent Code Generator Pass Configuration Options pass.
This defines the Use class.
xray instrumentation
Class for arbitrary precision integers.
Definition: APInt.h:76
an instruction to allocate memory on the stack
Definition: Instructions.h:58
bool isStaticAlloca() const
Return true if this alloca is in the entry block of the function and is a constant size.
Align getAlign() const
Return the alignment of the memory that is being allocated by the instruction.
Definition: Instructions.h:125
PointerType * getType() const
Overload to return most specific pointer type.
Definition: Instructions.h:100
Type * getAllocatedType() const
Return the type that is being allocated by the instruction.
Definition: Instructions.h:118
bool isArrayAllocation() const
Return true if there is an allocation size parameter to the allocation instruction that is not 1.
const Value * getArraySize() const
Get the number of elements allocated.
Definition: Instructions.h:96
Represent the analysis usage information of a pass.
AnalysisUsage & addRequired()
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
This class represents an incoming formal argument to a Function.
Definition: Argument.h:28
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory),...
Definition: ArrayRef.h:41
bool empty() const
empty - Check if the array is empty.
Definition: ArrayRef.h:160
An immutable pass that tracks lazily created AssumptionCache objects.
static BranchProbability getBranchProbStackProtector(bool IsLikely)
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1227
bool doesNotCapture(unsigned OpNo) const
Determine whether this data operand is not captured.
Definition: InstrTypes.h:1730
Function * getCalledFunction() const
Returns the function called, or null if this is an indirect function invocation or the function signa...
Definition: InstrTypes.h:1449
bool doesNotAccessMemory(unsigned OpNo) const
Definition: InstrTypes.h:1771
bool hasFnAttr(Attribute::AttrKind Kind) const
Determine whether this call has the given attribute.
Definition: InstrTypes.h:1535
User::op_iterator arg_begin()
Return the iterator pointing to the beginning of the argument list.
Definition: InstrTypes.h:1369
bool isNoInline() const
Return true if the call should not be inlined.
Definition: InstrTypes.h:1922
User::op_iterator arg_end()
Return the iterator pointing to the end of the argument list.
Definition: InstrTypes.h:1375
This class represents a function call, abstracting a target machine's calling convention.
static Constant * get(Type *Ty, uint64_t V, bool IsSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:888
This class represents a range of values.
Definition: ConstantRange.h:47
ConstantRange add(const ConstantRange &Other) const
Return a new range representing the possible values resulting from an addition of a value in this ran...
bool contains(const APInt &Val) const
Return true if the specified value is in the set.
Subprogram description.
This class represents an Operation in the Expression.
A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:110
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:313
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree.
Definition: Dominators.h:165
A handy container for a FunctionType+Callee-pointer pair, which can be passed around as a single enti...
Definition: DerivedTypes.h:168
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:311
virtual bool runOnFunction(Function &F)=0
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
AllocaInst * CreateAlloca(Type *Ty, unsigned AddrSpace, Value *ArraySize=nullptr, const Twine &Name="")
Definition: IRBuilder.h:1769
Value * CreatePointerCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2140
Value * CreateIntToPtr(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2092
void SetCurrentDebugLocation(DebugLoc L)
Set location information used by debugging information.
Definition: IRBuilder.h:212
Value * CreateICmpNE(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2215
Value * CreateSub(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1335
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2097
LoadInst * CreateLoad(Type *Ty, Value *Ptr, const char *Name)
Provided to resolve 'CreateLoad(Ty, Ptr, "...")' correctly, instead of converting the string to 'bool...
Definition: IRBuilder.h:1786
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1466
StoreInst * CreateStore(Value *Val, Value *Ptr, bool isVolatile=false)
Definition: IRBuilder.h:1799
Value * CreatePtrToInt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2087
Value * CreateIntCast(Value *V, Type *DestTy, bool isSigned, const Twine &Name="")
Definition: IRBuilder.h:2166
void SetInsertPoint(BasicBlock *TheBB)
This specifies that created instructions should be appended to the end of the specified block.
Definition: IRBuilder.h:180
Type * getVoidTy()
Fetch the type representing void.
Definition: IRBuilder.h:550
CallInst * CreateCall(FunctionType *FTy, Value *Callee, ArrayRef< Value * > Args=std::nullopt, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2382
Value * CreateGEP(Type *Ty, Value *Ptr, ArrayRef< Value * > IdxList, const Twine &Name="", bool IsInBounds=false)
Definition: IRBuilder.h:1862
CallInst * CreateMemCpy(Value *Dst, MaybeAlign DstAlign, Value *Src, MaybeAlign SrcAlign, uint64_t Size, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *TBAAStructTag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memcpy between the specified pointers.
Definition: IRBuilder.h:650
Value * CreateMul(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1352
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:2636
This class captures the data input to the InlineFunction call, and records the auxiliary results prod...
Definition: Cloning.h:202
bool isSuccess() const
Definition: InlineCost.h:188
InstListType::iterator eraseFromParent()
This method unlinks 'this' from the containing basic block and deletes it.
Definition: Instruction.cpp:93
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:47
MDNode * createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight)
Return metadata containing two branch weights.
Definition: MDBuilder.cpp:37
Metadata node.
Definition: Metadata.h:1037
static MDTuple * get(LLVMContext &Context, ArrayRef< Metadata * > MDs)
Definition: Metadata.h:1461
This is the common base class for memset/memcpy/memmove.
A Module instance is used to store all the information related to an LLVM module.
Definition: Module.h:65
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
virtual void getAnalysisUsage(AnalysisUsage &) const
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: Pass.cpp:98
This class represents an analyzed expression in the program.
Type * getType() const
Return the LLVM type of this SCEV expression.
The main scalar evolution driver.
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:366
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements.
Definition: SmallPtrSet.h:451
bool empty() const
Definition: SmallVector.h:94
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:577
void push_back(const T &Elt)
Definition: SmallVector.h:416
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
Definition: SmallVector.h:1200
This class represents a set of interesting instructions where an alloca is live.
Definition: StackLifetime.h:63
Compute live ranges of allocas.
Definition: StackLifetime.h:37
This base class for TargetLowering contains the SelectionDAG-independent parts that can be used from ...
Primary interface to the complete machine description for the target machine.
Definition: TargetMachine.h:78
Target-Independent Code Generator Pass Configuration Options.
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
A Use represents the edge between a Value definition and its users.
Definition: Use.h:43
LLVM Value Representation.
Definition: Value.h:74
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:255
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:534
use_iterator use_begin()
Definition: Value.h:360
bool use_empty() const
Definition: Value.h:344
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:1074
bool hasName() const
Definition: Value.h:261
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:309
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:383
NodeTy * getNextNode()
Get the next node, or nullptr for the list tail.
Definition: ilist_node.h:316
Compute the layout of an unsafe stack frame.
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
Definition: CallingConv.h:24
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
Function * getDeclaration(Module *M, ID id, ArrayRef< Type * > Tys=std::nullopt)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:1444
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:445
PointerTypeMap run(const Module &M)
Compute the PointerTypeMap for the module M.
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
@ Offset
Definition: DWP.cpp:440
FunctionPass * createSafeStackPass()
This pass splits the stack into a safe stack and an unsafe stack to protect against stack-based overf...
Definition: SafeStack.cpp:939
iterator_range< early_inc_iterator_impl< detail::IterOfRange< RangeT > > > make_early_inc_range(RangeT &&Range)
Make a range that does early increment to allow mutation of the underlying range without disrupting i...
Definition: STLExtras.h:665
InlineResult isInlineViable(Function &Callee)
Minimal filter to detect invalid constructs for inlining.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:156
uint64_t alignTo(uint64_t Size, Align A)
Returns a multiple of A needed to store Size bytes.
Definition: Alignment.h:155
void initializeSafeStackLegacyPassPass(PassRegistry &)
InlineResult InlineFunction(CallBase &CB, InlineFunctionInfo &IFI, bool MergeAttributes=false, AAResults *CalleeAAR=nullptr, bool InsertLifetime=true, Function *ForwardVarArgsTo=nullptr)
This function inlines the called function into the basic block of the caller.
void replaceDbgValueForAlloca(AllocaInst *AI, Value *NewAllocaAddress, DIBuilder &Builder, int Offset=0)
Replaces multiple llvm.dbg.value instructions when the alloca it describes is replaced with a new val...
Definition: Local.cpp:2149
constexpr unsigned BitWidth
Definition: BitmaskEnum.h:191
Instruction * SplitBlockAndInsertIfThen(Value *Cond, BasicBlock::iterator SplitBefore, bool Unreachable, MDNode *BranchWeights=nullptr, DomTreeUpdater *DTU=nullptr, LoopInfo *LI=nullptr, BasicBlock *ThenBlock=nullptr)
Split the containing block at the specified instruction - everything before SplitBefore stays in the ...
bool replaceDbgDeclare(Value *Address, Value *NewAddress, DIBuilder &Builder, uint8_t DIExprFlags, int Offset)
Replaces llvm.dbg.declare instruction when the address it describes is replaced with a new value.
Definition: Local.cpp:2103
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:39
uint64_t value() const
This is a hole in the type system and should not be abused.
Definition: Alignment.h:85
This struct is a compact representation of a valid (power of two) or undefined (0) alignment.
Definition: Alignment.h:117