1//===- LowerMemIntrinsics.cpp ----------------------------------*- C++ -*--===//
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#include "llvm/Transforms/Utils/LowerMemIntrinsics.h"
10#include "llvm/Analysis/ScalarEvolution.h"
11#include "llvm/Analysis/TargetTransformInfo.h"
12#include "llvm/IR/IRBuilder.h"
13#include "llvm/IR/IntrinsicInst.h"
14#include "llvm/IR/MDBuilder.h"
15#include "llvm/Support/Debug.h"
16#include "llvm/Support/MathExtras.h"
17#include "llvm/Transforms/Utils/BasicBlockUtils.h"
18#include <optional>
19
20#define DEBUG_TYPE "lower-mem-intrinsics"
21
22using namespace llvm;
23
24void llvm::createMemCpyLoopKnownSize(
25 Instruction *InsertBefore, Value *SrcAddr, Value *DstAddr,
26 ConstantInt *CopyLen, Align SrcAlign, Align DstAlign, bool SrcIsVolatile,
27 bool DstIsVolatile, bool CanOverlap, const TargetTransformInfo &TTI,
28 std::optional<uint32_t> AtomicElementSize) {
29 // No need to expand zero length copies.
30 if (CopyLen->isZero())
31 return;
32
33 BasicBlock *PreLoopBB = InsertBefore->getParent();
34 BasicBlock *PostLoopBB = nullptr;
35 Function *ParentFunc = PreLoopBB->getParent();
36 LLVMContext &Ctx = PreLoopBB->getContext();
37 const DataLayout &DL = ParentFunc->getParent()->getDataLayout();
38 MDBuilder MDB(Ctx);
39 MDNode *NewDomain = MDB.createAnonymousAliasScopeDomain(Name: "MemCopyDomain");
40 StringRef Name = "MemCopyAliasScope";
41 MDNode *NewScope = MDB.createAnonymousAliasScope(Domain: NewDomain, Name);
42
43 unsigned SrcAS = cast<PointerType>(Val: SrcAddr->getType())->getAddressSpace();
44 unsigned DstAS = cast<PointerType>(Val: DstAddr->getType())->getAddressSpace();
45
46 Type *TypeOfCopyLen = CopyLen->getType();
47 Type *LoopOpType = TTI.getMemcpyLoopLoweringType(
48 Context&: Ctx, Length: CopyLen, SrcAddrSpace: SrcAS, DestAddrSpace: DstAS, SrcAlign: SrcAlign.value(), DestAlign: DstAlign.value(),
49 AtomicElementSize);
50 assert((!AtomicElementSize || !LoopOpType->isVectorTy()) &&
51 "Atomic memcpy lowering is not supported for vector operand type");
52
53 unsigned LoopOpSize = DL.getTypeStoreSize(Ty: LoopOpType);
54 assert((!AtomicElementSize || LoopOpSize % *AtomicElementSize == 0) &&
55 "Atomic memcpy lowering is not supported for selected operand size");
56
57 uint64_t LoopEndCount = CopyLen->getZExtValue() / LoopOpSize;
58
59 if (LoopEndCount != 0) {
60 // Split
61 PostLoopBB = PreLoopBB->splitBasicBlock(I: InsertBefore, BBName: "memcpy-split");
62 BasicBlock *LoopBB =
63 BasicBlock::Create(Context&: Ctx, Name: "load-store-loop", Parent: ParentFunc, InsertBefore: PostLoopBB);
64 PreLoopBB->getTerminator()->setSuccessor(Idx: 0, BB: LoopBB);
65
66 IRBuilder<> PLBuilder(PreLoopBB->getTerminator());
67
68 Align PartDstAlign(commonAlignment(A: DstAlign, Offset: LoopOpSize));
69 Align PartSrcAlign(commonAlignment(A: SrcAlign, Offset: LoopOpSize));
70
71 IRBuilder<> LoopBuilder(LoopBB);
72 PHINode *LoopIndex = LoopBuilder.CreatePHI(Ty: TypeOfCopyLen, NumReservedValues: 2, Name: "loop-index");
73 LoopIndex->addIncoming(V: ConstantInt::get(Ty: TypeOfCopyLen, V: 0U), BB: PreLoopBB);
74 // Loop Body
75 Value *SrcGEP =
76 LoopBuilder.CreateInBoundsGEP(Ty: LoopOpType, Ptr: SrcAddr, IdxList: LoopIndex);
77 LoadInst *Load = LoopBuilder.CreateAlignedLoad(Ty: LoopOpType, Ptr: SrcGEP,
78 Align: PartSrcAlign, isVolatile: SrcIsVolatile);
79 if (!CanOverlap) {
80 // Set alias scope for loads.
81 Load->setMetadata(KindID: LLVMContext::MD_alias_scope,
82 Node: MDNode::get(Context&: Ctx, MDs: NewScope));
83 }
84 Value *DstGEP =
85 LoopBuilder.CreateInBoundsGEP(Ty: LoopOpType, Ptr: DstAddr, IdxList: LoopIndex);
86 StoreInst *Store = LoopBuilder.CreateAlignedStore(
87 Val: Load, Ptr: DstGEP, Align: PartDstAlign, isVolatile: DstIsVolatile);
88 if (!CanOverlap) {
89 // Indicate that stores don't overlap loads.
90 Store->setMetadata(KindID: LLVMContext::MD_noalias, Node: MDNode::get(Context&: Ctx, MDs: NewScope));
91 }
92 if (AtomicElementSize) {
93 Load->setAtomic(Ordering: AtomicOrdering::Unordered);
94 Store->setAtomic(Ordering: AtomicOrdering::Unordered);
95 }
96 Value *NewIndex =
97 LoopBuilder.CreateAdd(LHS: LoopIndex, RHS: ConstantInt::get(Ty: TypeOfCopyLen, V: 1U));
98 LoopIndex->addIncoming(V: NewIndex, BB: LoopBB);
99
100 // Create the loop branch condition.
101 Constant *LoopEndCI = ConstantInt::get(Ty: TypeOfCopyLen, V: LoopEndCount);
102 LoopBuilder.CreateCondBr(Cond: LoopBuilder.CreateICmpULT(LHS: NewIndex, RHS: LoopEndCI),
103 True: LoopBB, False: PostLoopBB);
104 }
105
106 uint64_t BytesCopied = LoopEndCount * LoopOpSize;
107 uint64_t RemainingBytes = CopyLen->getZExtValue() - BytesCopied;
108 if (RemainingBytes) {
109 IRBuilder<> RBuilder(PostLoopBB ? PostLoopBB->getFirstNonPHI()
110 : InsertBefore);
111
112 SmallVector<Type *, 5> RemainingOps;
113 TTI.getMemcpyLoopResidualLoweringType(OpsOut&: RemainingOps, Context&: Ctx, RemainingBytes,
114 SrcAddrSpace: SrcAS, DestAddrSpace: DstAS, SrcAlign: SrcAlign.value(),
115 DestAlign: DstAlign.value(), AtomicCpySize: AtomicElementSize);
116
117 for (auto *OpTy : RemainingOps) {
118 Align PartSrcAlign(commonAlignment(A: SrcAlign, Offset: BytesCopied));
119 Align PartDstAlign(commonAlignment(A: DstAlign, Offset: BytesCopied));
120
121 // Calculate the new index
122 unsigned OperandSize = DL.getTypeStoreSize(Ty: OpTy);
123 assert(
124 (!AtomicElementSize || OperandSize % *AtomicElementSize == 0) &&
125 "Atomic memcpy lowering is not supported for selected operand size");
126
127 uint64_t GepIndex = BytesCopied / OperandSize;
128 assert(GepIndex * OperandSize == BytesCopied &&
129 "Division should have no Remainder!");
130
131 Value *SrcGEP = RBuilder.CreateInBoundsGEP(
132 Ty: OpTy, Ptr: SrcAddr, IdxList: ConstantInt::get(Ty: TypeOfCopyLen, V: GepIndex));
133 LoadInst *Load =
134 RBuilder.CreateAlignedLoad(Ty: OpTy, Ptr: SrcGEP, Align: PartSrcAlign, isVolatile: SrcIsVolatile);
135 if (!CanOverlap) {
136 // Set alias scope for loads.
137 Load->setMetadata(KindID: LLVMContext::MD_alias_scope,
138 Node: MDNode::get(Context&: Ctx, MDs: NewScope));
139 }
140 Value *DstGEP = RBuilder.CreateInBoundsGEP(
141 Ty: OpTy, Ptr: DstAddr, IdxList: ConstantInt::get(Ty: TypeOfCopyLen, V: GepIndex));
142 StoreInst *Store = RBuilder.CreateAlignedStore(Val: Load, Ptr: DstGEP, Align: PartDstAlign,
143 isVolatile: DstIsVolatile);
144 if (!CanOverlap) {
145 // Indicate that stores don't overlap loads.
146 Store->setMetadata(KindID: LLVMContext::MD_noalias, Node: MDNode::get(Context&: Ctx, MDs: NewScope));
147 }
148 if (AtomicElementSize) {
149 Load->setAtomic(Ordering: AtomicOrdering::Unordered);
150 Store->setAtomic(Ordering: AtomicOrdering::Unordered);
151 }
152 BytesCopied += OperandSize;
153 }
154 }
155 assert(BytesCopied == CopyLen->getZExtValue() &&
156 "Bytes copied should match size in the call!");
157}
158
159// \returns \p Len udiv \p OpSize, checking for optimization opportunities.
160static Value *getRuntimeLoopCount(const DataLayout &DL, IRBuilderBase &B,
161 Value *Len, Value *OpSize,
162 unsigned OpSizeVal) {
163 // For powers of 2, we can lshr by log2 instead of using udiv.
164 if (isPowerOf2_32(Value: OpSizeVal))
165 return B.CreateLShr(LHS: Len, RHS: Log2_32(Value: OpSizeVal));
166 return B.CreateUDiv(LHS: Len, RHS: OpSize);
167}
168
169// \returns \p Len urem \p OpSize, checking for optimization opportunities.
170static Value *getRuntimeLoopRemainder(const DataLayout &DL, IRBuilderBase &B,
171 Value *Len, Value *OpSize,
172 unsigned OpSizeVal) {
173 // For powers of 2, we can and by (OpSizeVal - 1) instead of using urem.
174 if (isPowerOf2_32(Value: OpSizeVal))
175 return B.CreateAnd(LHS: Len, RHS: OpSizeVal - 1);
176 return B.CreateURem(LHS: Len, RHS: OpSize);
177}
178
179void llvm::createMemCpyLoopUnknownSize(
180 Instruction *InsertBefore, Value *SrcAddr, Value *DstAddr, Value *CopyLen,
181 Align SrcAlign, Align DstAlign, bool SrcIsVolatile, bool DstIsVolatile,
182 bool CanOverlap, const TargetTransformInfo &TTI,
183 std::optional<uint32_t> AtomicElementSize) {
184 BasicBlock *PreLoopBB = InsertBefore->getParent();
185 BasicBlock *PostLoopBB =
186 PreLoopBB->splitBasicBlock(I: InsertBefore, BBName: "post-loop-memcpy-expansion");
187
188 Function *ParentFunc = PreLoopBB->getParent();
189 const DataLayout &DL = ParentFunc->getParent()->getDataLayout();
190 LLVMContext &Ctx = PreLoopBB->getContext();
191 MDBuilder MDB(Ctx);
192 MDNode *NewDomain = MDB.createAnonymousAliasScopeDomain(Name: "MemCopyDomain");
193 StringRef Name = "MemCopyAliasScope";
194 MDNode *NewScope = MDB.createAnonymousAliasScope(Domain: NewDomain, Name);
195
196 unsigned SrcAS = cast<PointerType>(Val: SrcAddr->getType())->getAddressSpace();
197 unsigned DstAS = cast<PointerType>(Val: DstAddr->getType())->getAddressSpace();
198
199 Type *LoopOpType = TTI.getMemcpyLoopLoweringType(
200 Context&: Ctx, Length: CopyLen, SrcAddrSpace: SrcAS, DestAddrSpace: DstAS, SrcAlign: SrcAlign.value(), DestAlign: DstAlign.value(),
201 AtomicElementSize);
202 assert((!AtomicElementSize || !LoopOpType->isVectorTy()) &&
203 "Atomic memcpy lowering is not supported for vector operand type");
204 unsigned LoopOpSize = DL.getTypeStoreSize(Ty: LoopOpType);
205 assert((!AtomicElementSize || LoopOpSize % *AtomicElementSize == 0) &&
206 "Atomic memcpy lowering is not supported for selected operand size");
207
208 IRBuilder<> PLBuilder(PreLoopBB->getTerminator());
209
210 // Calculate the loop trip count, and remaining bytes to copy after the loop.
211 Type *CopyLenType = CopyLen->getType();
212 IntegerType *ILengthType = dyn_cast<IntegerType>(Val: CopyLenType);
213 assert(ILengthType &&
214 "expected size argument to memcpy to be an integer type!");
215 Type *Int8Type = Type::getInt8Ty(C&: Ctx);
216 bool LoopOpIsInt8 = LoopOpType == Int8Type;
217 ConstantInt *CILoopOpSize = ConstantInt::get(Ty: ILengthType, V: LoopOpSize);
218 Value *RuntimeLoopCount = LoopOpIsInt8
219 ? CopyLen
220 : getRuntimeLoopCount(DL, B&: PLBuilder, Len: CopyLen,
221 OpSize: CILoopOpSize, OpSizeVal: LoopOpSize);
222
223 BasicBlock *LoopBB =
224 BasicBlock::Create(Context&: Ctx, Name: "loop-memcpy-expansion", Parent: ParentFunc, InsertBefore: PostLoopBB);
225 IRBuilder<> LoopBuilder(LoopBB);
226
227 Align PartSrcAlign(commonAlignment(A: SrcAlign, Offset: LoopOpSize));
228 Align PartDstAlign(commonAlignment(A: DstAlign, Offset: LoopOpSize));
229
230 PHINode *LoopIndex = LoopBuilder.CreatePHI(Ty: CopyLenType, NumReservedValues: 2, Name: "loop-index");
231 LoopIndex->addIncoming(V: ConstantInt::get(Ty: CopyLenType, V: 0U), BB: PreLoopBB);
232
233 Value *SrcGEP = LoopBuilder.CreateInBoundsGEP(Ty: LoopOpType, Ptr: SrcAddr, IdxList: LoopIndex);
234 LoadInst *Load = LoopBuilder.CreateAlignedLoad(Ty: LoopOpType, Ptr: SrcGEP,
235 Align: PartSrcAlign, isVolatile: SrcIsVolatile);
236 if (!CanOverlap) {
237 // Set alias scope for loads.
238 Load->setMetadata(KindID: LLVMContext::MD_alias_scope, Node: MDNode::get(Context&: Ctx, MDs: NewScope));
239 }
240 Value *DstGEP = LoopBuilder.CreateInBoundsGEP(Ty: LoopOpType, Ptr: DstAddr, IdxList: LoopIndex);
241 StoreInst *Store =
242 LoopBuilder.CreateAlignedStore(Val: Load, Ptr: DstGEP, Align: PartDstAlign, isVolatile: DstIsVolatile);
243 if (!CanOverlap) {
244 // Indicate that stores don't overlap loads.
245 Store->setMetadata(KindID: LLVMContext::MD_noalias, Node: MDNode::get(Context&: Ctx, MDs: NewScope));
246 }
247 if (AtomicElementSize) {
248 Load->setAtomic(Ordering: AtomicOrdering::Unordered);
249 Store->setAtomic(Ordering: AtomicOrdering::Unordered);
250 }
251 Value *NewIndex =
252 LoopBuilder.CreateAdd(LHS: LoopIndex, RHS: ConstantInt::get(Ty: CopyLenType, V: 1U));
253 LoopIndex->addIncoming(V: NewIndex, BB: LoopBB);
254
255 bool requiresResidual =
256 !LoopOpIsInt8 && !(AtomicElementSize && LoopOpSize == AtomicElementSize);
257 if (requiresResidual) {
258 Type *ResLoopOpType = AtomicElementSize
259 ? Type::getIntNTy(C&: Ctx, N: *AtomicElementSize * 8)
260 : Int8Type;
261 unsigned ResLoopOpSize = DL.getTypeStoreSize(Ty: ResLoopOpType);
262 assert((ResLoopOpSize == AtomicElementSize ? *AtomicElementSize : 1) &&
263 "Store size is expected to match type size");
264
265 Value *RuntimeResidual = getRuntimeLoopRemainder(DL, B&: PLBuilder, Len: CopyLen,
266 OpSize: CILoopOpSize, OpSizeVal: LoopOpSize);
267 Value *RuntimeBytesCopied = PLBuilder.CreateSub(LHS: CopyLen, RHS: RuntimeResidual);
268
269 // Loop body for the residual copy.
270 BasicBlock *ResLoopBB = BasicBlock::Create(Context&: Ctx, Name: "loop-memcpy-residual",
271 Parent: PreLoopBB->getParent(),
272 InsertBefore: PostLoopBB);
273 // Residual loop header.
274 BasicBlock *ResHeaderBB = BasicBlock::Create(
275 Context&: Ctx, Name: "loop-memcpy-residual-header", Parent: PreLoopBB->getParent(), InsertBefore: nullptr);
276
277 // Need to update the pre-loop basic block to branch to the correct place.
278 // branch to the main loop if the count is non-zero, branch to the residual
279 // loop if the copy size is smaller then 1 iteration of the main loop but
280 // non-zero and finally branch to after the residual loop if the memcpy
281 // size is zero.
282 ConstantInt *Zero = ConstantInt::get(Ty: ILengthType, V: 0U);
283 PLBuilder.CreateCondBr(Cond: PLBuilder.CreateICmpNE(LHS: RuntimeLoopCount, RHS: Zero),
284 True: LoopBB, False: ResHeaderBB);
285 PreLoopBB->getTerminator()->eraseFromParent();
286
287 LoopBuilder.CreateCondBr(
288 Cond: LoopBuilder.CreateICmpULT(LHS: NewIndex, RHS: RuntimeLoopCount), True: LoopBB,
289 False: ResHeaderBB);
290
291 // Determine if we need to branch to the residual loop or bypass it.
292 IRBuilder<> RHBuilder(ResHeaderBB);
293 RHBuilder.CreateCondBr(Cond: RHBuilder.CreateICmpNE(LHS: RuntimeResidual, RHS: Zero),
294 True: ResLoopBB, False: PostLoopBB);
295
296 // Copy the residual with single byte load/store loop.
297 IRBuilder<> ResBuilder(ResLoopBB);
298 PHINode *ResidualIndex =
299 ResBuilder.CreatePHI(Ty: CopyLenType, NumReservedValues: 2, Name: "residual-loop-index");
300 ResidualIndex->addIncoming(V: Zero, BB: ResHeaderBB);
301
302 Value *FullOffset = ResBuilder.CreateAdd(LHS: RuntimeBytesCopied, RHS: ResidualIndex);
303 Value *SrcGEP =
304 ResBuilder.CreateInBoundsGEP(Ty: ResLoopOpType, Ptr: SrcAddr, IdxList: FullOffset);
305 LoadInst *Load = ResBuilder.CreateAlignedLoad(Ty: ResLoopOpType, Ptr: SrcGEP,
306 Align: PartSrcAlign, isVolatile: SrcIsVolatile);
307 if (!CanOverlap) {
308 // Set alias scope for loads.
309 Load->setMetadata(KindID: LLVMContext::MD_alias_scope,
310 Node: MDNode::get(Context&: Ctx, MDs: NewScope));
311 }
312 Value *DstGEP =
313 ResBuilder.CreateInBoundsGEP(Ty: ResLoopOpType, Ptr: DstAddr, IdxList: FullOffset);
314 StoreInst *Store = ResBuilder.CreateAlignedStore(Val: Load, Ptr: DstGEP, Align: PartDstAlign,
315 isVolatile: DstIsVolatile);
316 if (!CanOverlap) {
317 // Indicate that stores don't overlap loads.
318 Store->setMetadata(KindID: LLVMContext::MD_noalias, Node: MDNode::get(Context&: Ctx, MDs: NewScope));
319 }
320 if (AtomicElementSize) {
321 Load->setAtomic(Ordering: AtomicOrdering::Unordered);
322 Store->setAtomic(Ordering: AtomicOrdering::Unordered);
323 }
324 Value *ResNewIndex = ResBuilder.CreateAdd(
325 LHS: ResidualIndex, RHS: ConstantInt::get(Ty: CopyLenType, V: ResLoopOpSize));
326 ResidualIndex->addIncoming(V: ResNewIndex, BB: ResLoopBB);
327
328 // Create the loop branch condition.
329 ResBuilder.CreateCondBr(
330 Cond: ResBuilder.CreateICmpULT(LHS: ResNewIndex, RHS: RuntimeResidual), True: ResLoopBB,
331 False: PostLoopBB);
332 } else {
333 // In this case the loop operand type was a byte, and there is no need for a
334 // residual loop to copy the remaining memory after the main loop.
335 // We do however need to patch up the control flow by creating the
336 // terminators for the preloop block and the memcpy loop.
337 ConstantInt *Zero = ConstantInt::get(Ty: ILengthType, V: 0U);
338 PLBuilder.CreateCondBr(Cond: PLBuilder.CreateICmpNE(LHS: RuntimeLoopCount, RHS: Zero),
339 True: LoopBB, False: PostLoopBB);
340 PreLoopBB->getTerminator()->eraseFromParent();
341 LoopBuilder.CreateCondBr(
342 Cond: LoopBuilder.CreateICmpULT(LHS: NewIndex, RHS: RuntimeLoopCount), True: LoopBB,
343 False: PostLoopBB);
344 }
345}
346
347// Lower memmove to IR. memmove is required to correctly copy overlapping memory
348// regions; therefore, it has to check the relative positions of the source and
349// destination pointers and choose the copy direction accordingly.
350//
351// The code below is an IR rendition of this C function:
352//
353// void* memmove(void* dst, const void* src, size_t n) {
354// unsigned char* d = dst;
355// const unsigned char* s = src;
356// if (s < d) {
357// // copy backwards
358// while (n--) {
359// d[n] = s[n];
360// }
361// } else {
362// // copy forward
363// for (size_t i = 0; i < n; ++i) {
364// d[i] = s[i];
365// }
366// }
367// return dst;
368// }
369static void createMemMoveLoop(Instruction *InsertBefore, Value *SrcAddr,
370 Value *DstAddr, Value *CopyLen, Align SrcAlign,
371 Align DstAlign, bool SrcIsVolatile,
372 bool DstIsVolatile,
373 const TargetTransformInfo &TTI) {
374 Type *TypeOfCopyLen = CopyLen->getType();
375 BasicBlock *OrigBB = InsertBefore->getParent();
376 Function *F = OrigBB->getParent();
377 const DataLayout &DL = F->getParent()->getDataLayout();
378 // TODO: Use different element type if possible?
379 Type *EltTy = Type::getInt8Ty(C&: F->getContext());
380
381 // Create the a comparison of src and dst, based on which we jump to either
382 // the forward-copy part of the function (if src >= dst) or the backwards-copy
383 // part (if src < dst).
384 // SplitBlockAndInsertIfThenElse conveniently creates the basic if-then-else
385 // structure. Its block terminators (unconditional branches) are replaced by
386 // the appropriate conditional branches when the loop is built.
387 ICmpInst *PtrCompare = new ICmpInst(InsertBefore->getIterator(), ICmpInst::ICMP_ULT,
388 SrcAddr, DstAddr, "compare_src_dst");
389 Instruction *ThenTerm, *ElseTerm;
390 SplitBlockAndInsertIfThenElse(Cond: PtrCompare, SplitBefore: InsertBefore->getIterator(), ThenTerm: &ThenTerm,
391 ElseTerm: &ElseTerm);
392
393 // Each part of the function consists of two blocks:
394 // copy_backwards: used to skip the loop when n == 0
395 // copy_backwards_loop: the actual backwards loop BB
396 // copy_forward: used to skip the loop when n == 0
397 // copy_forward_loop: the actual forward loop BB
398 BasicBlock *CopyBackwardsBB = ThenTerm->getParent();
399 CopyBackwardsBB->setName("copy_backwards");
400 BasicBlock *CopyForwardBB = ElseTerm->getParent();
401 CopyForwardBB->setName("copy_forward");
402 BasicBlock *ExitBB = InsertBefore->getParent();
403 ExitBB->setName("memmove_done");
404
405 unsigned PartSize = DL.getTypeStoreSize(Ty: EltTy);
406 Align PartSrcAlign(commonAlignment(A: SrcAlign, Offset: PartSize));
407 Align PartDstAlign(commonAlignment(A: DstAlign, Offset: PartSize));
408
409 // Initial comparison of n == 0 that lets us skip the loops altogether. Shared
410 // between both backwards and forward copy clauses.
411 ICmpInst *CompareN =
412 new ICmpInst(OrigBB->getTerminator()->getIterator(), ICmpInst::ICMP_EQ, CopyLen,
413 ConstantInt::get(Ty: TypeOfCopyLen, V: 0), "compare_n_to_0");
414
415 // Copying backwards.
416 BasicBlock *LoopBB =
417 BasicBlock::Create(Context&: F->getContext(), Name: "copy_backwards_loop", Parent: F, InsertBefore: CopyForwardBB);
418 IRBuilder<> LoopBuilder(LoopBB);
419
420 PHINode *LoopPhi = LoopBuilder.CreatePHI(Ty: TypeOfCopyLen, NumReservedValues: 0);
421 Value *IndexPtr = LoopBuilder.CreateSub(
422 LHS: LoopPhi, RHS: ConstantInt::get(Ty: TypeOfCopyLen, V: 1), Name: "index_ptr");
423 Value *Element = LoopBuilder.CreateAlignedLoad(
424 Ty: EltTy, Ptr: LoopBuilder.CreateInBoundsGEP(Ty: EltTy, Ptr: SrcAddr, IdxList: IndexPtr),
425 Align: PartSrcAlign, Name: "element");
426 LoopBuilder.CreateAlignedStore(
427 Val: Element, Ptr: LoopBuilder.CreateInBoundsGEP(Ty: EltTy, Ptr: DstAddr, IdxList: IndexPtr),
428 Align: PartDstAlign);
429 LoopBuilder.CreateCondBr(
430 Cond: LoopBuilder.CreateICmpEQ(LHS: IndexPtr, RHS: ConstantInt::get(Ty: TypeOfCopyLen, V: 0)),
431 True: ExitBB, False: LoopBB);
432 LoopPhi->addIncoming(V: IndexPtr, BB: LoopBB);
433 LoopPhi->addIncoming(V: CopyLen, BB: CopyBackwardsBB);
434 BranchInst::Create(IfTrue: ExitBB, IfFalse: LoopBB, Cond: CompareN, InsertBefore: ThenTerm->getIterator());
435 ThenTerm->eraseFromParent();
436
437 // Copying forward.
438 BasicBlock *FwdLoopBB =
439 BasicBlock::Create(Context&: F->getContext(), Name: "copy_forward_loop", Parent: F, InsertBefore: ExitBB);
440 IRBuilder<> FwdLoopBuilder(FwdLoopBB);
441 PHINode *FwdCopyPhi = FwdLoopBuilder.CreatePHI(Ty: TypeOfCopyLen, NumReservedValues: 0, Name: "index_ptr");
442 Value *SrcGEP = FwdLoopBuilder.CreateInBoundsGEP(Ty: EltTy, Ptr: SrcAddr, IdxList: FwdCopyPhi);
443 Value *FwdElement =
444 FwdLoopBuilder.CreateAlignedLoad(Ty: EltTy, Ptr: SrcGEP, Align: PartSrcAlign, Name: "element");
445 Value *DstGEP = FwdLoopBuilder.CreateInBoundsGEP(Ty: EltTy, Ptr: DstAddr, IdxList: FwdCopyPhi);
446 FwdLoopBuilder.CreateAlignedStore(Val: FwdElement, Ptr: DstGEP, Align: PartDstAlign);
447 Value *FwdIndexPtr = FwdLoopBuilder.CreateAdd(
448 LHS: FwdCopyPhi, RHS: ConstantInt::get(Ty: TypeOfCopyLen, V: 1), Name: "index_increment");
449 FwdLoopBuilder.CreateCondBr(Cond: FwdLoopBuilder.CreateICmpEQ(LHS: FwdIndexPtr, RHS: CopyLen),
450 True: ExitBB, False: FwdLoopBB);
451 FwdCopyPhi->addIncoming(V: FwdIndexPtr, BB: FwdLoopBB);
452 FwdCopyPhi->addIncoming(V: ConstantInt::get(Ty: TypeOfCopyLen, V: 0), BB: CopyForwardBB);
453
454 BranchInst::Create(IfTrue: ExitBB, IfFalse: FwdLoopBB, Cond: CompareN, InsertBefore: ElseTerm->getIterator());
455 ElseTerm->eraseFromParent();
456}
457
458static void createMemSetLoop(Instruction *InsertBefore, Value *DstAddr,
459 Value *CopyLen, Value *SetValue, Align DstAlign,
460 bool IsVolatile) {
461 Type *TypeOfCopyLen = CopyLen->getType();
462 BasicBlock *OrigBB = InsertBefore->getParent();
463 Function *F = OrigBB->getParent();
464 const DataLayout &DL = F->getParent()->getDataLayout();
465 BasicBlock *NewBB =
466 OrigBB->splitBasicBlock(I: InsertBefore, BBName: "split");
467 BasicBlock *LoopBB
468 = BasicBlock::Create(Context&: F->getContext(), Name: "loadstoreloop", Parent: F, InsertBefore: NewBB);
469
470 IRBuilder<> Builder(OrigBB->getTerminator());
471
472 Builder.CreateCondBr(
473 Cond: Builder.CreateICmpEQ(LHS: ConstantInt::get(Ty: TypeOfCopyLen, V: 0), RHS: CopyLen), True: NewBB,
474 False: LoopBB);
475 OrigBB->getTerminator()->eraseFromParent();
476
477 unsigned PartSize = DL.getTypeStoreSize(Ty: SetValue->getType());
478 Align PartAlign(commonAlignment(A: DstAlign, Offset: PartSize));
479
480 IRBuilder<> LoopBuilder(LoopBB);
481 PHINode *LoopIndex = LoopBuilder.CreatePHI(Ty: TypeOfCopyLen, NumReservedValues: 0);
482 LoopIndex->addIncoming(V: ConstantInt::get(Ty: TypeOfCopyLen, V: 0), BB: OrigBB);
483
484 LoopBuilder.CreateAlignedStore(
485 Val: SetValue,
486 Ptr: LoopBuilder.CreateInBoundsGEP(Ty: SetValue->getType(), Ptr: DstAddr, IdxList: LoopIndex),
487 Align: PartAlign, isVolatile: IsVolatile);
488
489 Value *NewIndex =
490 LoopBuilder.CreateAdd(LHS: LoopIndex, RHS: ConstantInt::get(Ty: TypeOfCopyLen, V: 1));
491 LoopIndex->addIncoming(V: NewIndex, BB: LoopBB);
492
493 LoopBuilder.CreateCondBr(Cond: LoopBuilder.CreateICmpULT(LHS: NewIndex, RHS: CopyLen), True: LoopBB,
494 False: NewBB);
495}
496
497template <typename T>
498static bool canOverlap(MemTransferBase<T> *Memcpy, ScalarEvolution *SE) {
499 if (SE) {
500 auto *SrcSCEV = SE->getSCEV(V: Memcpy->getRawSource());
501 auto *DestSCEV = SE->getSCEV(V: Memcpy->getRawDest());
502 if (SE->isKnownPredicateAt(Pred: CmpInst::ICMP_NE, LHS: SrcSCEV, RHS: DestSCEV, CtxI: Memcpy))
503 return false;
504 }
505 return true;
506}
507
508void llvm::expandMemCpyAsLoop(MemCpyInst *Memcpy,
509 const TargetTransformInfo &TTI,
510 ScalarEvolution *SE) {
511 bool CanOverlap = canOverlap(Memcpy, SE);
512 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val: Memcpy->getLength())) {
513 createMemCpyLoopKnownSize(
514 /* InsertBefore */ Memcpy,
515 /* SrcAddr */ Memcpy->getRawSource(),
516 /* DstAddr */ Memcpy->getRawDest(),
517 /* CopyLen */ CI,
518 /* SrcAlign */ Memcpy->getSourceAlign().valueOrOne(),
519 /* DestAlign */ DstAlign: Memcpy->getDestAlign().valueOrOne(),
520 /* SrcIsVolatile */ Memcpy->isVolatile(),
521 /* DstIsVolatile */ Memcpy->isVolatile(),
522 /* CanOverlap */ CanOverlap,
523 /* TargetTransformInfo */ TTI);
524 } else {
525 createMemCpyLoopUnknownSize(
526 /* InsertBefore */ Memcpy,
527 /* SrcAddr */ Memcpy->getRawSource(),
528 /* DstAddr */ Memcpy->getRawDest(),
529 /* CopyLen */ Memcpy->getLength(),
530 /* SrcAlign */ Memcpy->getSourceAlign().valueOrOne(),
531 /* DestAlign */ DstAlign: Memcpy->getDestAlign().valueOrOne(),
532 /* SrcIsVolatile */ Memcpy->isVolatile(),
533 /* DstIsVolatile */ Memcpy->isVolatile(),
534 /* CanOverlap */ CanOverlap,
535 /* TargetTransformInfo */ TTI);
536 }
537}
538
539bool llvm::expandMemMoveAsLoop(MemMoveInst *Memmove,
540 const TargetTransformInfo &TTI) {
541 Value *CopyLen = Memmove->getLength();
542 Value *SrcAddr = Memmove->getRawSource();
543 Value *DstAddr = Memmove->getRawDest();
544 Align SrcAlign = Memmove->getSourceAlign().valueOrOne();
545 Align DstAlign = Memmove->getDestAlign().valueOrOne();
546 bool SrcIsVolatile = Memmove->isVolatile();
547 bool DstIsVolatile = SrcIsVolatile;
548 IRBuilder<> CastBuilder(Memmove);
549
550 unsigned SrcAS = SrcAddr->getType()->getPointerAddressSpace();
551 unsigned DstAS = DstAddr->getType()->getPointerAddressSpace();
552 if (SrcAS != DstAS) {
553 if (!TTI.addrspacesMayAlias(AS0: SrcAS, AS1: DstAS)) {
554 // We may not be able to emit a pointer comparison, but we don't have
555 // to. Expand as memcpy.
556 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val: CopyLen)) {
557 createMemCpyLoopKnownSize(/*InsertBefore=*/Memmove, SrcAddr, DstAddr,
558 CopyLen: CI, SrcAlign, DstAlign, SrcIsVolatile,
559 DstIsVolatile,
560 /*CanOverlap=*/false, TTI);
561 } else {
562 createMemCpyLoopUnknownSize(/*InsertBefore=*/Memmove, SrcAddr, DstAddr,
563 CopyLen, SrcAlign, DstAlign, SrcIsVolatile,
564 DstIsVolatile,
565 /*CanOverlap=*/false, TTI);
566 }
567
568 return true;
569 }
570
571 if (TTI.isValidAddrSpaceCast(FromAS: DstAS, ToAS: SrcAS))
572 DstAddr = CastBuilder.CreateAddrSpaceCast(V: DstAddr, DestTy: SrcAddr->getType());
573 else if (TTI.isValidAddrSpaceCast(FromAS: SrcAS, ToAS: DstAS))
574 SrcAddr = CastBuilder.CreateAddrSpaceCast(V: SrcAddr, DestTy: DstAddr->getType());
575 else {
576 // We don't know generically if it's legal to introduce an
577 // addrspacecast. We need to know either if it's legal to insert an
578 // addrspacecast, or if the address spaces cannot alias.
579 LLVM_DEBUG(
580 dbgs() << "Do not know how to expand memmove between different "
581 "address spaces\n");
582 return false;
583 }
584 }
585
586 createMemMoveLoop(
587 /*InsertBefore=*/Memmove, SrcAddr, DstAddr, CopyLen, SrcAlign, DstAlign,
588 SrcIsVolatile, DstIsVolatile, TTI);
589 return true;
590}
591
592void llvm::expandMemSetAsLoop(MemSetInst *Memset) {
593 createMemSetLoop(/* InsertBefore */ Memset,
594 /* DstAddr */ Memset->getRawDest(),
595 /* CopyLen */ Memset->getLength(),
596 /* SetValue */ Memset->getValue(),
597 /* Alignment */ DstAlign: Memset->getDestAlign().valueOrOne(),
598 IsVolatile: Memset->isVolatile());
599}
600
601void llvm::expandAtomicMemCpyAsLoop(AtomicMemCpyInst *AtomicMemcpy,
602 const TargetTransformInfo &TTI,
603 ScalarEvolution *SE) {
604 if (ConstantInt *CI = dyn_cast<ConstantInt>(Val: AtomicMemcpy->getLength())) {
605 createMemCpyLoopKnownSize(
606 /* InsertBefore */ AtomicMemcpy,
607 /* SrcAddr */ AtomicMemcpy->getRawSource(),
608 /* DstAddr */ AtomicMemcpy->getRawDest(),
609 /* CopyLen */ CI,
610 /* SrcAlign */ AtomicMemcpy->getSourceAlign().valueOrOne(),
611 /* DestAlign */ DstAlign: AtomicMemcpy->getDestAlign().valueOrOne(),
612 /* SrcIsVolatile */ AtomicMemcpy->isVolatile(),
613 /* DstIsVolatile */ AtomicMemcpy->isVolatile(),
614 /* CanOverlap */ false, // SrcAddr & DstAddr may not overlap by spec.
615 /* TargetTransformInfo */ TTI,
616 /* AtomicCpySize */ AtomicElementSize: AtomicMemcpy->getElementSizeInBytes());
617 } else {
618 createMemCpyLoopUnknownSize(
619 /* InsertBefore */ AtomicMemcpy,
620 /* SrcAddr */ AtomicMemcpy->getRawSource(),
621 /* DstAddr */ AtomicMemcpy->getRawDest(),
622 /* CopyLen */ AtomicMemcpy->getLength(),
623 /* SrcAlign */ AtomicMemcpy->getSourceAlign().valueOrOne(),
624 /* DestAlign */ DstAlign: AtomicMemcpy->getDestAlign().valueOrOne(),
625 /* SrcIsVolatile */ AtomicMemcpy->isVolatile(),
626 /* DstIsVolatile */ AtomicMemcpy->isVolatile(),
627 /* CanOverlap */ false, // SrcAddr & DstAddr may not overlap by spec.
628 /* TargetTransformInfo */ TTI,
629 /* AtomicCpySize */ AtomicElementSize: AtomicMemcpy->getElementSizeInBytes());
630 }
631}
632

source code of llvm/lib/Transforms/Utils/LowerMemIntrinsics.cpp