MemCpyOptimizer.cpp revision 777d2306b36816a53bc1ae1244c0dc7d998ae691
1a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===- MemCpyOptimizer.cpp - Optimize use of memcpy and friends -----------===// 2a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 3a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// The LLVM Compiler Infrastructure 4a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 5a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// This file is distributed under the University of Illinois Open Source 6a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// License. See LICENSE.TXT for details. 7a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 8a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 9a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 10a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// This pass performs various transformations related to eliminating memcpy 11a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// calls, or transforming sets of stores into memset's. 12a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 13a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 14a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 15a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#define DEBUG_TYPE "memcpyopt" 16a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Transforms/Scalar.h" 17a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/IntrinsicInst.h" 18a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Instructions.h" 19a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/ADT/SmallVector.h" 20a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/ADT/Statistic.h" 21a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/Dominators.h" 22a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/AliasAnalysis.h" 23a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/MemoryDependenceAnalysis.h" 24a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Support/Debug.h" 25a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Support/GetElementPtrTypeIterator.h" 26a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Target/TargetData.h" 27a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include <list> 28a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonusing namespace llvm; 29a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 30a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonSTATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted"); 31a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonSTATISTIC(NumMemSetInfer, "Number of memsets inferred"); 32a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 33a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// isBytewiseValue - If the specified value can be set by repeating the same 34a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// byte in memory, return the i8 value that it is represented with. This is 35a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// true for all i8 values obviously, but is also true for i32 0, i32 -1, 36a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated 37a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// byte store (e.g. i16 0x1234), return null. 38a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic Value *isBytewiseValue(Value *V) { 39a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All byte-wide stores are splatable, even of arbitrary variables. 40a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (V->getType() == Type::Int8Ty) return V; 41a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 42a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Constant float and double values can be handled as integer values if the 43a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // corresponding integer value is "byteable". An important case is 0.0. 44a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { 45a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (CFP->getType() == Type::FloatTy) 46a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson V = ConstantExpr::getBitCast(CFP, Type::Int32Ty); 47a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (CFP->getType() == Type::DoubleTy) 48a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson V = ConstantExpr::getBitCast(CFP, Type::Int64Ty); 49a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Don't handle long double formats, which have strange constraints. 50a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 51a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 52a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can handle constant integers that are power of two in size and a 53a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // multiple of 8 bits. 54a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 55a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Width = CI->getBitWidth(); 56a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isPowerOf2_32(Width) && Width > 8) { 57a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can handle this value if the recursive binary decomposition is the 58a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // same at all levels. 59a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson APInt Val = CI->getValue(); 60a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson APInt Val2; 61a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (Val.getBitWidth() != 8) { 62a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NextWidth = Val.getBitWidth()/2; 63a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val2 = Val.lshr(NextWidth); 64a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val2.trunc(Val.getBitWidth()/2); 65a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val.trunc(Val.getBitWidth()/2); 66a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 67a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the top/bottom halves aren't the same, reject it. 68a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Val != Val2) 69a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return 0; 70a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 71a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return ConstantInt::get(Val); 72a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 73a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 74a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 75a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Conceptually, we could handle things like: 76a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %a = zext i8 %X to i16 77a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %b = shl i16 %a, 8 78a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %c = or i16 %a, %b 79a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // but until there is an example that actually needs this, it doesn't seem 80a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // worth worrying about. 81a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return 0; 82a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 83a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 84a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic int64_t GetOffsetFromIndex(const GetElementPtrInst *GEP, unsigned Idx, 85a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool &VariableIdxFound, TargetData &TD) { 86a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Skip over the first indices. 87a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson gep_type_iterator GTI = gep_type_begin(GEP); 88a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 1; i != Idx; ++i, ++GTI) 89a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /*skip along*/; 90a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 91a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Compute the offset implied by the rest of the indices. 92a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset = 0; 93a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { 94a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i)); 95a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (OpC == 0) 96a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return VariableIdxFound = true; 97a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (OpC->isZero()) continue; // No offset. 98a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 99a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Handle struct indices, which add their field offset to the pointer. 100a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 101a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); 102a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 103a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 104a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 105a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we have a sequential type like an array or vector. Multiply 106a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the index by the ElementSize. 107777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 108a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset += Size*OpC->getSExtValue(); 109a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 110a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 111a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return Offset; 112a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 113a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 114a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// IsPointerOffset - Return true if Ptr1 is provably equal to Ptr2 plus a 115a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// constant offset, and return that constant offset. For example, Ptr1 might 116a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// be &A[42], and Ptr2 might be &A[40]. In this case offset would be -8. 117a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset, 118a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD) { 119a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical 120a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // base. After that base, they may have some number of common (and 121a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // potentially variable) indices. After that they handle some constant 122a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // offset, which determines their offset from each other. At this point, we 123a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // handle no other case. 124a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(Ptr1); 125a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(Ptr2); 126a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0)) 127a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 128a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 129a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Skip any common indices and track the GEP types. 130a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Idx = 1; 131a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx) 132a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx)) 133a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 134a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 135a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool VariableIdxFound = false; 136a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, TD); 137a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, TD); 138a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (VariableIdxFound) return false; 139a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 140a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset = Offset2-Offset1; 141a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 142a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 143a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 144a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 145a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// MemsetRange - Represents a range of memset'd bytes with the ByteVal value. 146a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// This allows us to analyze stores like: 147a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+1 148a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+0 149a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+3 150a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+2 151a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// which sometimes happens with stores to arrays of structs etc. When we see 152a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the first store, we make a range [1, 2). The second store extends the range 153a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// to [0, 2). The third makes a new range [2, 3). The fourth store joins the 154a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// two ranges into [0, 3) which is memset'able. 155a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 156a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstruct MemsetRange { 157a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Start/End - A semi range that describes the span that this range covers. 158a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The range is closed at the start and open at the end: [Start, End). 159a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Start, End; 160a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 161a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// StartPtr - The getelementptr instruction that points to the start of the 162a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// range. 163a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr; 164a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 165a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// Alignment - The known alignment of the first store. 166a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Alignment; 167a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 168a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// TheStores - The actual stores that make up this range. 169a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<StoreInst*, 16> TheStores; 170a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 171a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool isProfitableToUseMemset(const TargetData &TD) const; 172a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 173a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson}; 174a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} // end anon namespace 175a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 176a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const { 177a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we found more than 8 stores to merge or 64 bytes, use memset. 178a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (TheStores.size() >= 8 || End-Start >= 64) return true; 179a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 180a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Assume that the code generator is capable of merging pairs of stores 181a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // together if it wants to. 182a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (TheStores.size() <= 2) return false; 183a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 184a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have fewer than 8 stores, it can still be worthwhile to do this. 185a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // For example, merging 4 i8 stores into an i32 store is useful almost always. 186a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // However, merging 2 32-bit stores isn't useful on a 32-bit architecture (the 187a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset will be split into 2 32-bit stores anyway) and doing so can 188a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // pessimize the llvm optimizer. 189a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 190a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we don't have perfect knowledge here, make some assumptions: assume 191a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the maximum GPR width is the same size as the pointer size and assume that 192a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // this width can be stored. If so, check to see whether we will end up 193a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // actually reducing the number of stores used. 194a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Bytes = unsigned(End-Start); 195a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NumPointerStores = Bytes/TD.getPointerSize(); 196a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 197a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Assume the remaining bytes if any are done a byte at a time. 198a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NumByteStores = Bytes - NumPointerStores*TD.getPointerSize(); 199a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 200a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we will reduce the # stores (according to this heuristic), do the 201a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32 202a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // etc. 203a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return TheStores.size() > NumPointerStores+NumByteStores; 204a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 205a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 206a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 207a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 208a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonclass MemsetRanges { 209a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// Ranges - A sorted list of the memset ranges. We use std::list here 210a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// because each element is relatively large and expensive to copy. 211a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson std::list<MemsetRange> Ranges; 212a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson typedef std::list<MemsetRange>::iterator range_iterator; 213a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD; 214a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonpublic: 215a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRanges(TargetData &td) : TD(td) {} 216a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 217a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson typedef std::list<MemsetRange>::const_iterator const_iterator; 218a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const_iterator begin() const { return Ranges.begin(); } 219a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const_iterator end() const { return Ranges.end(); } 220a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool empty() const { return Ranges.empty(); } 221a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 222a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson void addStore(int64_t OffsetFromFirst, StoreInst *SI); 223a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson}; 224a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 225a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} // end anon namespace 226a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 227a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 228a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// addStore - Add a new store to the MemsetRanges data structure. This adds a 229a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// new range for the specified store at the specified offset, merging into 230a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// existing ranges as appropriate. 231a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonvoid MemsetRanges::addStore(int64_t Start, StoreInst *SI) { 232a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t End = Start+TD.getTypeStoreSize(SI->getOperand(0)->getType()); 233a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 234a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Do a linear search of the ranges to see if this can be joined and/or to 235a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // find the insertion point in the list. We keep the ranges sorted for 236a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // simplicity here. This is a linear search of a linked list, which is ugly, 237a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // however the number of ranges is limited, so this won't get crazy slow. 238a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson range_iterator I = Ranges.begin(), E = Ranges.end(); 239a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 240a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (I != E && Start > I->End) 241a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++I; 242a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 243a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We now know that I == E, in which case we didn't find anything to merge 244a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // with, or that Start <= I->End. If End < I->Start or I == E, then we need 245a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to insert a new range. Handle this now. 246a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (I == E || End < I->Start) { 247a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRange &R = *Ranges.insert(I, MemsetRange()); 248a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.Start = Start; 249a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.End = End; 250a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.StartPtr = SI->getPointerOperand(); 251a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.Alignment = SI->getAlignment(); 252a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.TheStores.push_back(SI); 253a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return; 254a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 255a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 256a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This store overlaps with I, add it. 257a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.push_back(SI); 258a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 259a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // At this point, we may have an interval that completely contains our store. 260a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If so, just add it to the interval and return. 261a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (I->Start <= Start && I->End >= End) 262a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return; 263a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 264a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and End >= I->Start so the range overlaps 265a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // but is not entirely contained within the range. 266a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 267a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // See if the range extends the start of the range. In this case, it couldn't 268a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // possibly cause it to join the prior range, because otherwise we would have 269a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // stopped on *it*. 270a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Start < I->Start) { 271a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->Start = Start; 272a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->StartPtr = SI->getPointerOperand(); 273a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 274a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 275a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and Start >= I->Start (so the startpoint 276a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // is in or right at the end of I), and that End >= I->Start. Extend I out to 277a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // End. 278a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (End > I->End) { 279a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = End; 2809c0f146d50ccc3ba780d4854b8e14422430013efNick Lewycky range_iterator NextI = I; 281a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (++NextI != E && End >= NextI->Start) { 282a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Merge the range in. 283a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end()); 284a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextI->End > I->End) 285a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = NextI->End; 286a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.erase(NextI); 287a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson NextI = I; 288a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 289a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 290a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 291a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 292a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 293a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt Pass 294a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 295a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 296a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 297a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 298a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson class VISIBILITY_HIDDEN MemCpyOpt : public FunctionPass { 299a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool runOnFunction(Function &F); 300a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson public: 301a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson static char ID; // Pass identification, replacement for typeid 302ae73dc1448d25b02cabc7c64c86c64371453dda8Dan Gohman MemCpyOpt() : FunctionPass(&ID) {} 303a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 304a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson private: 305a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This transformation requires dominator postdominator info 306a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson virtual void getAnalysisUsage(AnalysisUsage &AU) const { 307a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.setPreservesCFG(); 308a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<DominatorTree>(); 309a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<MemoryDependenceAnalysis>(); 310a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<AliasAnalysis>(); 311a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<TargetData>(); 312a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<AliasAnalysis>(); 313a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<MemoryDependenceAnalysis>(); 314a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<TargetData>(); 315a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 316a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 317a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Helper fuctions 318a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson bool processStore(StoreInst *SI, BasicBlock::iterator& BBI); 319a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson bool processMemCpy(MemCpyInst* M); 320a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson bool performCallSlotOptzn(MemCpyInst* cpy, CallInst* C); 321a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool iterateOnFunction(Function &F); 322a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 323a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 324a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson char MemCpyOpt::ID = 0; 325a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 326a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 327a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// createMemCpyOptPass - The public interface to this file... 328a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonFunctionPass *llvm::createMemCpyOptPass() { return new MemCpyOpt(); } 329a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 330a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic RegisterPass<MemCpyOpt> X("memcpyopt", 331a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson "MemCpy Optimization"); 332a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 333a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 334a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 335a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// processStore - When GVN is scanning forward over instructions, we look for 336a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// some other patterns to fold away. In particular, this looks for stores to 337a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// neighboring locations of memory. If it sees enough consequtive ones 338a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// (currently 4) it attempts to merge them together into a memcpy/memset. 339a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator& BBI) { 340a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (SI->isVolatile()) return false; 341a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 342a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // There are two cases that are interesting for this code to handle: memcpy 343a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // and memset. Right now we only handle memset. 344a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 345a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Ensure that the value being stored is something that can be memset'able a 346a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // byte at a time like "0" or "-1" or any width, as well as things like 347a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 0xA0A0A0A0 and 0.0. 348a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *ByteVal = isBytewiseValue(SI->getOperand(0)); 349a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!ByteVal) 350a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 351a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 352a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD = getAnalysis<TargetData>(); 353a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 354a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 355a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Okay, so we now have a single store that can be splatable. Scan to find 356a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // all subsequent stores of the same value to offset from the same pointer. 357a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Join these together into ranges, so we can decide whether contiguous blocks 358a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // are stored. 359a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRanges Ranges(TD); 360a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 361a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr = SI->getPointerOperand(); 362a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 363a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator BI = SI; 364a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (++BI; !isa<TerminatorInst>(BI); ++BI) { 365a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) { 366a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the call is readnone, ignore it, otherwise bail out. We don't even 367a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // allow readonly here because we don't want something like: 368a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A). 369a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.getModRefBehavior(CallSite::get(BI)) == 370a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::DoesNotAccessMemory) 371a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 372a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 373a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // TODO: If this is a memset, try to join it in. 374a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 375a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 376a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (isa<VAArgInst>(BI) || isa<LoadInst>(BI)) 377a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 378a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 379a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a non-store instruction it is fine, ignore it. 380a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StoreInst *NextStore = dyn_cast<StoreInst>(BI); 381a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore == 0) continue; 382a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 383a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a store, see if we can merge it in. 384a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore->isVolatile()) break; 385a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 386a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this stored value is of the same byte-splattable value. 387a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ByteVal != isBytewiseValue(NextStore->getOperand(0))) 388a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 389a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 390a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this store is to a constant offset from the start ptr. 391a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset; 392a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, TD)) 393a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 394a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 395a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(Offset, NextStore); 396a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 397a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 398a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have no ranges, then we just had a single store with nothing that 399a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // could be merged in. This is a very common case of course. 400a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Ranges.empty()) 401a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 402a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 403a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we had at least one store that could be merged in, add the starting 404a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // store as well. We try to avoid this unless there is at least something 405a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // interesting as a small compile-time optimization. 406a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(0, SI); 407a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 408a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 409a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Function *MemSetF = 0; 410a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 411a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now that we have full information about ranges, loop over the ranges and 412a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // emit memset's for anything big enough to be worthwhile. 413a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool MadeChange = false; 414a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end(); 415a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) { 416a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const MemsetRange &Range = *I; 417a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 418a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Range.TheStores.size() == 1) continue; 419a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 420a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If it is profitable to lower this range to memset, do so now. 421a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!Range.isProfitableToUseMemset(TD)) 422a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 423a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 424a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we do want to transform this! Create a new memset. We put 425a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memset right before the first instruction that isn't part of this 426a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset block. This ensure that the memset is dominated by any addressing 427a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // instruction needed by the start of the block. 428a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator InsertPt = BI; 429a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 430824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner if (MemSetF == 0) { 431824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner const Type *Tys[] = {Type::Int64Ty}; 432a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemSetF = Intrinsic::getDeclaration(SI->getParent()->getParent() 433824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner ->getParent(), Intrinsic::memset, 434824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner Tys, 1); 435824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner } 436a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 437a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Get the starting pointer of the block. 438a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr = Range.StartPtr; 439a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 440a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Cast the start ptr to be i8* as memset requires. 441a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const Type *i8Ptr = PointerType::getUnqual(Type::Int8Ty); 442a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (StartPtr->getType() != i8Ptr) 443a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr = new BitCastInst(StartPtr, i8Ptr, StartPtr->getNameStart(), 444a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson InsertPt); 445a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 446a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *Ops[] = { 447a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr, ByteVal, // Start, value 448a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt::get(Type::Int64Ty, Range.End-Range.Start), // size 449a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt::get(Type::Int32Ty, Range.Alignment) // align 450a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 451a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *C = CallInst::Create(MemSetF, Ops, Ops+4, "", InsertPt); 452a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson DEBUG(cerr << "Replace stores:\n"; 453a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i) 454a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cerr << *Range.TheStores[i]; 455a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cerr << "With: " << *C); C=C; 456a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 457a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Don't invalidate the iterator 458a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson BBI = BI; 459a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 460a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Zap all the stores. 461a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (SmallVector<StoreInst*, 16>::const_iterator SI = Range.TheStores.begin(), 462a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson SE = Range.TheStores.end(); SI != SE; ++SI) 463a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson (*SI)->eraseFromParent(); 464a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++NumMemSetInfer; 465a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MadeChange = true; 466a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 467a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 468a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return MadeChange; 469a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 470a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 471a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 472a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// performCallSlotOptzn - takes a memcpy and a call that it depends on, 473a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// and checks for the possibility of a call slot optimization by having 474a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the call write its result directly into the destination of the memcpy. 475a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool MemCpyOpt::performCallSlotOptzn(MemCpyInst *cpy, CallInst *C) { 476a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The general transformation to keep in mind is 477a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 478a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., src, ...) 479a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 480a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 481a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // -> 482a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 483a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 484a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., dest, ...) 485a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 486a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since moving the memcpy is technically awkward, we additionally check that 487a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // src only holds uninitialized values at the moment of the call, meaning that 488a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy can be discarded rather than moved. 489a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 490a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Deliberately get the source and destination with bitcasts stripped away, 491a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // because we'll need to do type comparisons based on the underlying type. 492a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value* cpyDest = cpy->getDest(); 493a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value* cpySrc = cpy->getSource(); 494a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson CallSite CS = CallSite::get(C); 495a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 496a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We need to be able to reason about the size of the memcpy, so we require 497a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that it be a constant. 498a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* cpyLength = dyn_cast<ConstantInt>(cpy->getLength()); 499a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!cpyLength) 500a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 501a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 502a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Require that src be an alloca. This simplifies the reasoning considerably. 503a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AllocaInst* srcAlloca = dyn_cast<AllocaInst>(cpySrc); 504a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcAlloca) 505a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 506a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 507a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that all of src is copied to dest. 508a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData& TD = getAnalysis<TargetData>(); 509a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 510a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize()); 511a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcArraySize) 512a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 513a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 514777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t srcSize = TD.getTypeAllocSize(srcAlloca->getAllocatedType()) * 515a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcArraySize->getZExtValue(); 516a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 517a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpyLength->getZExtValue() < srcSize) 518a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 519a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 520a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that accessing the first srcSize bytes of dest will not cause a 521a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // trap. Otherwise the transform is invalid since it might cause a trap 522a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to occur earlier than it otherwise would. 523a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AllocaInst* A = dyn_cast<AllocaInst>(cpyDest)) { 524a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The destination is an alloca. Check it is larger than srcSize. 525a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* destArraySize = dyn_cast<ConstantInt>(A->getArraySize()); 526a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!destArraySize) 527a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 528a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 529777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t destSize = TD.getTypeAllocSize(A->getAllocatedType()) * 530a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson destArraySize->getZExtValue(); 531a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 532a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 533a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 534a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (Argument* A = dyn_cast<Argument>(cpyDest)) { 535a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the destination is an sret parameter then only accesses that are 536a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // outside of the returned struct type can trap. 537a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!A->hasStructRetAttr()) 538a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 539a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 540a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const Type* StructTy = cast<PointerType>(A->getType())->getElementType(); 541777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t destSize = TD.getTypeAllocSize(StructTy); 542a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 543a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 544a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 545a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else { 546a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 547a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 548a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 549a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that src is not accessed except via the call and the memcpy. This 550a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // guarantees that it holds only undefined values when passed in (so the final 551a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy can be dropped), that it is not read or written between the call and 552a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy, and that writing beyond the end of it is undefined. 553a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(), 554a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcAlloca->use_end()); 555a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (!srcUseList.empty()) { 556a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson User* UI = srcUseList.back(); 557a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.pop_back(); 558a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 559009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (isa<BitCastInst>(UI)) { 560a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 561a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) 562a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.push_back(*I); 563009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson } else if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(UI)) { 564009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (G->hasAllZeroIndices()) 565009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 566009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson I != E; ++I) 567009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson srcUseList.push_back(*I); 568009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson else 569009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson return false; 570a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (UI != C && UI != cpy) { 571a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 572a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 573a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 574a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 575a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we're changing the parameter to the callsite, we need to make sure 576a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that what would be the new parameter dominates the callsite. 577a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson DominatorTree& DT = getAnalysis<DominatorTree>(); 578a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Instruction* cpyDestInst = dyn_cast<Instruction>(cpyDest)) 579a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!DT.dominates(cpyDestInst, C)) 580a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 581a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 582a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // In addition to knowing that the call does not access src in some 583a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // unexpected manner, for example via a global, which we deduce from 584a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the use analysis, we also need to know that it does not sneakily 585a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // access dest. We rely on AA to figure this out for us. 586a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis& AA = getAnalysis<AliasAnalysis>(); 587a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.getModRefInfo(C, cpy->getRawDest(), srcSize) != 588a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoModRef) 589a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 590a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 591a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All the checks have passed, so do the transformation. 59212cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson bool changedArgument = false; 593a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0; i < CS.arg_size(); ++i) 594009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (CS.getArgument(i)->stripPointerCasts() == cpySrc) { 595a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpySrc->getType() != cpyDest->getType()) 5967cbd8a3e92221437048b484d5ef9c0a22d0f8c58Gabor Greif cpyDest = CastInst::CreatePointerCast(cpyDest, cpySrc->getType(), 597a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cpyDest->getName(), C); 59812cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson changedArgument = true; 599009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (CS.getArgument(i)->getType() != cpyDest->getType()) 600009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.setArgument(i, CastInst::CreatePointerCast(cpyDest, 601009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.getArgument(i)->getType(), cpyDest->getName(), C)); 602009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson else 603009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.setArgument(i, cpyDest); 604a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 605a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 60612cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson if (!changedArgument) 60712cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson return false; 60812cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson 609a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Drop any cached information about the call, because we may have changed 610a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // its dependence information by changing its parameter. 611a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>(); 6124f8c18c7c757875cfa45383e7cf33d65d2c4d564Chris Lattner MD.removeInstruction(C); 613a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 614a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Remove the memcpy 615a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MD.removeInstruction(cpy); 616a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson cpy->eraseFromParent(); 617a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson NumMemCpyInstr++; 618a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 619a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 620a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 621a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 622a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which 623a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be 624a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// a memcpy from X to Z (or potentially a memmove, depending on circumstances). 625a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// This allows later passes to remove the first memcpy altogether. 626a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool MemCpyOpt::processMemCpy(MemCpyInst* M) { 627a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>(); 628a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 629a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // The are two possible optimizations we can do for memcpy: 630a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // a) memcpy-memcpy xform which exposes redundance for DSE 631a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // b) call-memcpy xform for return slot optimization 6324c724006256032e827177afeae04ea62436796e7Chris Lattner MemDepResult dep = MD.getDependency(M); 633b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner if (!dep.isClobber()) 634a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson return false; 635b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner if (!isa<MemCpyInst>(dep.getInst())) { 6364c724006256032e827177afeae04ea62436796e7Chris Lattner if (CallInst* C = dyn_cast<CallInst>(dep.getInst())) 6379dcace3cafb4da5c3d94f3b89e54ea0d7164a286Owen Anderson return performCallSlotOptzn(M, C); 638b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner return false; 6399dcace3cafb4da5c3d94f3b89e54ea0d7164a286Owen Anderson } 640a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 6414c724006256032e827177afeae04ea62436796e7Chris Lattner MemCpyInst* MDep = cast<MemCpyInst>(dep.getInst()); 642a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 643a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can only transforms memcpy's where the dest of one is the source of the 644a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // other 645a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (M->getSource() != MDep->getDest()) 646a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 647a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 648a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Second, the length of the memcpy's must be the same, or the preceeding one 649a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // must be larger than the following one. 650a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* C1 = dyn_cast<ConstantInt>(MDep->getLength()); 651a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* C2 = dyn_cast<ConstantInt>(M->getLength()); 652a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!C1 || !C2) 653a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 654a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 655a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t DepSize = C1->getValue().getZExtValue(); 656a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t CpySize = C2->getValue().getZExtValue(); 657a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 658a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (DepSize < CpySize) 659a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 660a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 661a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Finally, we have to make sure that the dest of the second does not 662a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // alias the source of the first 663a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis& AA = getAnalysis<AliasAnalysis>(); 664a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) != 665a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoAlias) 666a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 667a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) != 668a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoAlias) 669a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 670a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize) 671a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson != AliasAnalysis::NoAlias) 672a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 673a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 674a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If all checks passed, then we can transform these memcpy's 675824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner const Type *Tys[1]; 676824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner Tys[0] = M->getLength()->getType(); 677a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Function* MemCpyFun = Intrinsic::getDeclaration( 678a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson M->getParent()->getParent()->getParent(), 679824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner M->getIntrinsicID(), Tys, 1); 680a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 681dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner Value *Args[4] = { 682dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner M->getRawDest(), MDep->getRawSource(), M->getLength(), M->getAlignmentCst() 683dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner }; 684a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 685dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner CallInst* C = CallInst::Create(MemCpyFun, Args, Args+4, "", M); 686a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 68702e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson 68802e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // If C and M don't interfere, then this is a valid transformation. If they 68902e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // did, this would mean that the two sources overlap, which would be bad. 69039f372e23e49cecb8db2eb7120eb331173e50c74Chris Lattner if (MD.getDependency(C) == dep) { 6914f8c18c7c757875cfa45383e7cf33d65d2c4d564Chris Lattner MD.removeInstruction(M); 692a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson M->eraseFromParent(); 69302e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson NumMemCpyInstr++; 694a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 695a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 696a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 69702e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // Otherwise, there was no point in doing this, so we remove the call we 69802e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // inserted and act like nothing happened. 699a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MD.removeInstruction(C); 700a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson C->eraseFromParent(); 70102e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson return false; 702a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 703a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 704a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt::runOnFunction - This is the main transformation entry point for a 705a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// function. 706a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 707a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemCpyOpt::runOnFunction(Function& F) { 708a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 709a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool changed = false; 710a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool shouldContinue = true; 711a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 712a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (shouldContinue) { 713a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson shouldContinue = iterateOnFunction(F); 714a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson changed |= shouldContinue; 715a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 716a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 717a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return changed; 718a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 719a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 720a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 721a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt::iterateOnFunction - Executes one iteration of GVN 722a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemCpyOpt::iterateOnFunction(Function &F) { 723a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool changed_function = false; 724a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 725a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Walk all instruction in the function 726a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) { 727a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); 728a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BI != BE;) { 729a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Avoid invalidating the iterator 730a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson Instruction* I = BI++; 731a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 732a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson if (StoreInst *SI = dyn_cast<StoreInst>(I)) 733a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson changed_function |= processStore(SI, BI); 734529bd53411c6f583fd8ed435adf4c0f923d185fdTorok Edwin else if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) { 735a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson changed_function |= processMemCpy(M); 736a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson } 737a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 738a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 739a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 740a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return changed_function; 741a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 742