LLVM  14.0.0git
MemoryLocation.cpp
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1 //===- MemoryLocation.cpp - Memory location descriptions -------------------==//
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 
11 #include "llvm/IR/BasicBlock.h"
12 #include "llvm/IR/DataLayout.h"
13 #include "llvm/IR/Instructions.h"
14 #include "llvm/IR/IntrinsicInst.h"
15 #include "llvm/IR/IntrinsicsARM.h"
16 #include "llvm/IR/LLVMContext.h"
17 #include "llvm/IR/Module.h"
18 #include "llvm/IR/Type.h"
19 using namespace llvm;
20 
22  OS << "LocationSize::";
23  if (*this == beforeOrAfterPointer())
24  OS << "beforeOrAfterPointer";
25  else if (*this == afterPointer())
26  OS << "afterPointer";
27  else if (*this == mapEmpty())
28  OS << "mapEmpty";
29  else if (*this == mapTombstone())
30  OS << "mapTombstone";
31  else if (isPrecise())
32  OS << "precise(" << getValue() << ')';
33  else
34  OS << "upperBound(" << getValue() << ')';
35 }
36 
38  const auto &DL = LI->getModule()->getDataLayout();
39 
40  return MemoryLocation(
41  LI->getPointerOperand(),
42  LocationSize::precise(DL.getTypeStoreSize(LI->getType())),
43  LI->getAAMetadata());
44 }
45 
47  const auto &DL = SI->getModule()->getDataLayout();
48 
49  return MemoryLocation(SI->getPointerOperand(),
50  LocationSize::precise(DL.getTypeStoreSize(
51  SI->getValueOperand()->getType())),
52  SI->getAAMetadata());
53 }
54 
56  return MemoryLocation(VI->getPointerOperand(),
57  LocationSize::afterPointer(), VI->getAAMetadata());
58 }
59 
61  const auto &DL = CXI->getModule()->getDataLayout();
62 
63  return MemoryLocation(CXI->getPointerOperand(),
64  LocationSize::precise(DL.getTypeStoreSize(
65  CXI->getCompareOperand()->getType())),
66  CXI->getAAMetadata());
67 }
68 
70  const auto &DL = RMWI->getModule()->getDataLayout();
71 
72  return MemoryLocation(RMWI->getPointerOperand(),
73  LocationSize::precise(DL.getTypeStoreSize(
74  RMWI->getValOperand()->getType())),
75  RMWI->getAAMetadata());
76 }
77 
79  switch (Inst->getOpcode()) {
80  case Instruction::Load:
81  return get(cast<LoadInst>(Inst));
82  case Instruction::Store:
83  return get(cast<StoreInst>(Inst));
84  case Instruction::VAArg:
85  return get(cast<VAArgInst>(Inst));
86  case Instruction::AtomicCmpXchg:
87  return get(cast<AtomicCmpXchgInst>(Inst));
88  case Instruction::AtomicRMW:
89  return get(cast<AtomicRMWInst>(Inst));
90  default:
91  return None;
92  }
93 }
94 
96  return getForSource(cast<AnyMemTransferInst>(MTI));
97 }
98 
100  return getForSource(cast<AnyMemTransferInst>(MTI));
101 }
102 
104  assert(MTI->getRawSource() == MTI->getArgOperand(1));
105  return getForArgument(MTI, 1, nullptr);
106 }
107 
109  return getForDest(cast<AnyMemIntrinsic>(MI));
110 }
111 
113  return getForDest(cast<AnyMemIntrinsic>(MI));
114 }
115 
117  assert(MI->getRawDest() == MI->getArgOperand(0));
118  return getForArgument(MI, 0, nullptr);
119 }
120 
123  if (!CB->onlyAccessesArgMemory())
124  return None;
125 
126  if (CB->hasOperandBundles())
127  // TODO: remove implementation restriction
128  return None;
129 
130  Value *UsedV = nullptr;
131  Optional<unsigned> UsedIdx;
132  for (unsigned i = 0; i < CB->arg_size(); i++) {
133  if (!CB->getArgOperand(i)->getType()->isPointerTy())
134  continue;
135  if (CB->onlyReadsMemory(i))
136  continue;
137  if (!UsedV) {
138  // First potentially writing parameter
139  UsedV = CB->getArgOperand(i);
140  UsedIdx = i;
141  continue;
142  }
143  UsedIdx = None;
144  if (UsedV != CB->getArgOperand(i))
145  // Can't describe writing to two distinct locations.
146  // TODO: This results in an inprecision when two values derived from the
147  // same object are passed as arguments to the same function.
148  return None;
149  }
150  if (!UsedV)
151  // We don't currently have a way to represent a "does not write" result
152  // and thus have to be conservative and return unknown.
153  return None;
154 
155  if (UsedIdx)
156  return getForArgument(CB, *UsedIdx, &TLI);
157  return MemoryLocation::getBeforeOrAfter(UsedV, CB->getAAMetadata());
158 }
159 
161  unsigned ArgIdx,
162  const TargetLibraryInfo *TLI) {
163  AAMDNodes AATags = Call->getAAMetadata();
164  const Value *Arg = Call->getArgOperand(ArgIdx);
165 
166  // We may be able to produce an exact size for known intrinsics.
167  if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Call)) {
168  const DataLayout &DL = II->getModule()->getDataLayout();
169 
170  switch (II->getIntrinsicID()) {
171  default:
172  break;
173  case Intrinsic::memset:
174  case Intrinsic::memcpy:
175  case Intrinsic::memcpy_inline:
176  case Intrinsic::memmove:
177  case Intrinsic::memcpy_element_unordered_atomic:
178  case Intrinsic::memmove_element_unordered_atomic:
179  case Intrinsic::memset_element_unordered_atomic:
180  assert((ArgIdx == 0 || ArgIdx == 1) &&
181  "Invalid argument index for memory intrinsic");
182  if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getArgOperand(2)))
183  return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
184  AATags);
186 
187  case Intrinsic::lifetime_start:
188  case Intrinsic::lifetime_end:
189  case Intrinsic::invariant_start:
190  assert(ArgIdx == 1 && "Invalid argument index");
191  return MemoryLocation(
192  Arg,
194  cast<ConstantInt>(II->getArgOperand(0))->getZExtValue()),
195  AATags);
196 
197  case Intrinsic::masked_load:
198  assert(ArgIdx == 0 && "Invalid argument index");
199  return MemoryLocation(
200  Arg,
201  LocationSize::upperBound(DL.getTypeStoreSize(II->getType())),
202  AATags);
203 
204  case Intrinsic::masked_store:
205  assert(ArgIdx == 1 && "Invalid argument index");
206  return MemoryLocation(
207  Arg,
209  DL.getTypeStoreSize(II->getArgOperand(0)->getType())),
210  AATags);
211 
212  case Intrinsic::invariant_end:
213  // The first argument to an invariant.end is a "descriptor" type (e.g. a
214  // pointer to a empty struct) which is never actually dereferenced.
215  if (ArgIdx == 0)
217  assert(ArgIdx == 2 && "Invalid argument index");
218  return MemoryLocation(
219  Arg,
221  cast<ConstantInt>(II->getArgOperand(1))->getZExtValue()),
222  AATags);
223 
224  case Intrinsic::arm_neon_vld1:
225  assert(ArgIdx == 0 && "Invalid argument index");
226  // LLVM's vld1 and vst1 intrinsics currently only support a single
227  // vector register.
228  return MemoryLocation(
229  Arg, LocationSize::precise(DL.getTypeStoreSize(II->getType())),
230  AATags);
231 
232  case Intrinsic::arm_neon_vst1:
233  assert(ArgIdx == 0 && "Invalid argument index");
234  return MemoryLocation(Arg,
235  LocationSize::precise(DL.getTypeStoreSize(
236  II->getArgOperand(1)->getType())),
237  AATags);
238  }
239 
240  assert(
241  !isa<AnyMemTransferInst>(II) &&
242  "all memory transfer intrinsics should be handled by the switch above");
243  }
244 
245  // We can bound the aliasing properties of memset_pattern16 just as we can
246  // for memcpy/memset. This is particularly important because the
247  // LoopIdiomRecognizer likes to turn loops into calls to memset_pattern16
248  // whenever possible.
249  LibFunc F;
250  if (TLI && TLI->getLibFunc(*Call, F) && TLI->has(F)) {
251  switch (F) {
252  case LibFunc_strcpy:
253  case LibFunc_strcat:
254  case LibFunc_strncat:
255  assert((ArgIdx == 0 || ArgIdx == 1) && "Invalid argument index for str function");
257 
258  case LibFunc_memset_chk: {
259  assert(ArgIdx == 0 && "Invalid argument index for memset_chk");
261  if (const auto *Len = dyn_cast<ConstantInt>(Call->getArgOperand(2))) {
262  // memset_chk writes at most Len bytes. It may write less, if Len
263  // exceeds the specified max size and aborts.
264  Size = LocationSize::upperBound(Len->getZExtValue());
265  }
266  return MemoryLocation(Arg, Size, AATags);
267  }
268  case LibFunc_strncpy: {
269  assert((ArgIdx == 0 || ArgIdx == 1) &&
270  "Invalid argument index for strncpy");
272  if (const auto *Len = dyn_cast<ConstantInt>(Call->getArgOperand(2))) {
273  // strncpy is guaranteed to write Len bytes, but only reads up to Len
274  // bytes.
275  Size = ArgIdx == 0 ? LocationSize::precise(Len->getZExtValue())
276  : LocationSize::upperBound(Len->getZExtValue());
277  }
278  return MemoryLocation(Arg, Size, AATags);
279  }
280  case LibFunc_memset_pattern16:
281  case LibFunc_memset_pattern4:
282  case LibFunc_memset_pattern8:
283  assert((ArgIdx == 0 || ArgIdx == 1) &&
284  "Invalid argument index for memset_pattern16");
285  if (ArgIdx == 1) {
286  unsigned Size = 16;
287  if (F == LibFunc_memset_pattern4)
288  Size = 4;
289  else if (F == LibFunc_memset_pattern8)
290  Size = 8;
292  }
293  if (const ConstantInt *LenCI =
294  dyn_cast<ConstantInt>(Call->getArgOperand(2)))
295  return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
296  AATags);
298  case LibFunc_bcmp:
299  case LibFunc_memcmp:
300  assert((ArgIdx == 0 || ArgIdx == 1) &&
301  "Invalid argument index for memcmp/bcmp");
302  if (const ConstantInt *LenCI =
303  dyn_cast<ConstantInt>(Call->getArgOperand(2)))
304  return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
305  AATags);
307  case LibFunc_memchr:
308  assert((ArgIdx == 0) && "Invalid argument index for memchr");
309  if (const ConstantInt *LenCI =
310  dyn_cast<ConstantInt>(Call->getArgOperand(2)))
311  return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
312  AATags);
314  case LibFunc_memccpy:
315  assert((ArgIdx == 0 || ArgIdx == 1) &&
316  "Invalid argument index for memccpy");
317  // We only know an upper bound on the number of bytes read/written.
318  if (const ConstantInt *LenCI =
319  dyn_cast<ConstantInt>(Call->getArgOperand(3)))
320  return MemoryLocation(
321  Arg, LocationSize::upperBound(LenCI->getZExtValue()), AATags);
323  default:
324  break;
325  };
326  }
327 
328  return MemoryLocation::getBeforeOrAfter(Call->getArgOperand(ArgIdx), AATags);
329 }
i
i
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Definition: MemoryLocation.cpp:21
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Return a location with information about the memory reference by the given instruction.
Definition: MemoryLocation.cpp:37
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Definition: DataLayout.h:113
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Any location after the base pointer (but still within the underlying object).
Definition: MemoryLocation.h:123
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Definition: MemoryLocation.h:226
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Definition: MemoryLocation.cpp:78
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Return a location representing a particular argument of a call.
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Tests whether a library function is available.
Definition: TargetLibraryInfo.h:325
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const DataLayout & getDataLayout() const
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Definition: MemoryLocation.cpp:108
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Definition: MemoryLocation.h:209