MemCpyOptimizer.cpp revision f41eaacee4a4a2d4339dd553626d98c73650c8c7
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" 19fa5cbd6d0fbda23fd669c8718e07b19001b2d21aOwen Anderson#include "llvm/LLVMContext.h" 20a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/ADT/SmallVector.h" 21a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/ADT/Statistic.h" 22a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/Dominators.h" 23a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/AliasAnalysis.h" 24a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/MemoryDependenceAnalysis.h" 25a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Support/Debug.h" 26a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Support/GetElementPtrTypeIterator.h" 27bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner#include "llvm/Support/raw_ostream.h" 28a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Target/TargetData.h" 29a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include <list> 30a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonusing namespace llvm; 31a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 32a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonSTATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted"); 33a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonSTATISTIC(NumMemSetInfer, "Number of memsets inferred"); 34a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 35a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// isBytewiseValue - If the specified value can be set by repeating the same 36a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// byte in memory, return the i8 value that it is represented with. This is 37a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// true for all i8 values obviously, but is also true for i32 0, i32 -1, 38a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated 39a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// byte store (e.g. i16 0x1234), return null. 4061c6ba85715fdcb66f746678879984151f1e5485Chris Lattnerstatic Value *isBytewiseValue(Value *V, LLVMContext &Context) { 41a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All byte-wide stores are splatable, even of arbitrary variables. 421d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson if (V->getType() == Type::getInt8Ty(Context)) return V; 43a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 44a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Constant float and double values can be handled as integer values if the 45a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // corresponding integer value is "byteable". An important case is 0.0. 46a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { 471d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson if (CFP->getType() == Type::getFloatTy(Context)) 481d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(Context)); 491d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson if (CFP->getType() == Type::getDoubleTy(Context)) 501d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(Context)); 51a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Don't handle long double formats, which have strange constraints. 52a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 53a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 54a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can handle constant integers that are power of two in size and a 55a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // multiple of 8 bits. 56a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 57a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Width = CI->getBitWidth(); 58a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isPowerOf2_32(Width) && Width > 8) { 59a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can handle this value if the recursive binary decomposition is the 60a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // same at all levels. 61a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson APInt Val = CI->getValue(); 62a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson APInt Val2; 63a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (Val.getBitWidth() != 8) { 64a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NextWidth = Val.getBitWidth()/2; 65a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val2 = Val.lshr(NextWidth); 66a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val2.trunc(Val.getBitWidth()/2); 67a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val.trunc(Val.getBitWidth()/2); 68a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 69a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the top/bottom halves aren't the same, reject it. 70a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Val != Val2) 71a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return 0; 72a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 73eed707b1e6097aac2bb6b3d47271f6300ace7f2eOwen Anderson return ConstantInt::get(Context, Val); 74a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 75a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 76a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 77a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Conceptually, we could handle things like: 78a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %a = zext i8 %X to i16 79a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %b = shl i16 %a, 8 80a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %c = or i16 %a, %b 81a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // but until there is an example that actually needs this, it doesn't seem 82a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // worth worrying about. 83a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return 0; 84a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 85a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 86a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic int64_t GetOffsetFromIndex(const GetElementPtrInst *GEP, unsigned Idx, 87a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool &VariableIdxFound, TargetData &TD) { 88a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Skip over the first indices. 89a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson gep_type_iterator GTI = gep_type_begin(GEP); 90a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 1; i != Idx; ++i, ++GTI) 91a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /*skip along*/; 92a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 93a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Compute the offset implied by the rest of the indices. 94a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset = 0; 95a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { 96a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i)); 97a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (OpC == 0) 98a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return VariableIdxFound = true; 99a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (OpC->isZero()) continue; // No offset. 100a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 101a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Handle struct indices, which add their field offset to the pointer. 102a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 103a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); 104a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 105a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 106a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 107a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we have a sequential type like an array or vector. Multiply 108a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the index by the ElementSize. 109777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 110a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset += Size*OpC->getSExtValue(); 111a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 112a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 113a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return Offset; 114a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 115a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 116a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// IsPointerOffset - Return true if Ptr1 is provably equal to Ptr2 plus a 117a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// constant offset, and return that constant offset. For example, Ptr1 might 118a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// be &A[42], and Ptr2 might be &A[40]. In this case offset would be -8. 119a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset, 120a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD) { 121a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical 122a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // base. After that base, they may have some number of common (and 123a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // potentially variable) indices. After that they handle some constant 124a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // offset, which determines their offset from each other. At this point, we 125a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // handle no other case. 126a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(Ptr1); 127a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(Ptr2); 128a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0)) 129a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 130a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 131a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Skip any common indices and track the GEP types. 132a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Idx = 1; 133a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx) 134a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx)) 135a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 136a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 137a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool VariableIdxFound = false; 138a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, TD); 139a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, TD); 140a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (VariableIdxFound) return false; 141a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 142a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset = Offset2-Offset1; 143a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 144a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 145a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 146a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 147a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// MemsetRange - Represents a range of memset'd bytes with the ByteVal value. 148a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// This allows us to analyze stores like: 149a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+1 150a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+0 151a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+3 152a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+2 153a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// which sometimes happens with stores to arrays of structs etc. When we see 154a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the first store, we make a range [1, 2). The second store extends the range 155a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// to [0, 2). The third makes a new range [2, 3). The fourth store joins the 156a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// two ranges into [0, 3) which is memset'able. 157a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 158a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstruct MemsetRange { 159a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Start/End - A semi range that describes the span that this range covers. 160a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The range is closed at the start and open at the end: [Start, End). 161a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Start, End; 162a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 163a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// StartPtr - The getelementptr instruction that points to the start of the 164a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// range. 165a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr; 166a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 167a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// Alignment - The known alignment of the first store. 168a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Alignment; 169a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 170a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// TheStores - The actual stores that make up this range. 171a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<StoreInst*, 16> TheStores; 172a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 173a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool isProfitableToUseMemset(const TargetData &TD) const; 174a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 175a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson}; 176a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} // end anon namespace 177a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 178a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const { 179a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we found more than 8 stores to merge or 64 bytes, use memset. 180a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (TheStores.size() >= 8 || End-Start >= 64) return true; 181a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 182a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Assume that the code generator is capable of merging pairs of stores 183a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // together if it wants to. 184a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (TheStores.size() <= 2) return false; 185a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 186a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have fewer than 8 stores, it can still be worthwhile to do this. 187a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // For example, merging 4 i8 stores into an i32 store is useful almost always. 188a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // However, merging 2 32-bit stores isn't useful on a 32-bit architecture (the 189a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset will be split into 2 32-bit stores anyway) and doing so can 190a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // pessimize the llvm optimizer. 191a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 192a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we don't have perfect knowledge here, make some assumptions: assume 193a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the maximum GPR width is the same size as the pointer size and assume that 194a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // this width can be stored. If so, check to see whether we will end up 195a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // actually reducing the number of stores used. 196a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Bytes = unsigned(End-Start); 197a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NumPointerStores = Bytes/TD.getPointerSize(); 198a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 199a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Assume the remaining bytes if any are done a byte at a time. 200a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NumByteStores = Bytes - NumPointerStores*TD.getPointerSize(); 201a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 202a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we will reduce the # stores (according to this heuristic), do the 203a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32 204a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // etc. 205a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return TheStores.size() > NumPointerStores+NumByteStores; 206a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 207a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 208a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 209a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 210a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonclass MemsetRanges { 211a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// Ranges - A sorted list of the memset ranges. We use std::list here 212a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// because each element is relatively large and expensive to copy. 213a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson std::list<MemsetRange> Ranges; 214a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson typedef std::list<MemsetRange>::iterator range_iterator; 215a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD; 216a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonpublic: 217a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRanges(TargetData &td) : TD(td) {} 218a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 219a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson typedef std::list<MemsetRange>::const_iterator const_iterator; 220a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const_iterator begin() const { return Ranges.begin(); } 221a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const_iterator end() const { return Ranges.end(); } 222a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool empty() const { return Ranges.empty(); } 223a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 224a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson void addStore(int64_t OffsetFromFirst, StoreInst *SI); 225a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson}; 226a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 227a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} // end anon namespace 228a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 229a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 230a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// addStore - Add a new store to the MemsetRanges data structure. This adds a 231a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// new range for the specified store at the specified offset, merging into 232a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// existing ranges as appropriate. 233a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonvoid MemsetRanges::addStore(int64_t Start, StoreInst *SI) { 234a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t End = Start+TD.getTypeStoreSize(SI->getOperand(0)->getType()); 235a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 236a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Do a linear search of the ranges to see if this can be joined and/or to 237a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // find the insertion point in the list. We keep the ranges sorted for 238a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // simplicity here. This is a linear search of a linked list, which is ugly, 239a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // however the number of ranges is limited, so this won't get crazy slow. 240a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson range_iterator I = Ranges.begin(), E = Ranges.end(); 241a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 242a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (I != E && Start > I->End) 243a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++I; 244a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 245a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We now know that I == E, in which case we didn't find anything to merge 246a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // with, or that Start <= I->End. If End < I->Start or I == E, then we need 247a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to insert a new range. Handle this now. 248a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (I == E || End < I->Start) { 249a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRange &R = *Ranges.insert(I, MemsetRange()); 250a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.Start = Start; 251a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.End = End; 252a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.StartPtr = SI->getPointerOperand(); 253a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.Alignment = SI->getAlignment(); 254a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.TheStores.push_back(SI); 255a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return; 256a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 257a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 258a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This store overlaps with I, add it. 259a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.push_back(SI); 260a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 261a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // At this point, we may have an interval that completely contains our store. 262a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If so, just add it to the interval and return. 263a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (I->Start <= Start && I->End >= End) 264a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return; 265a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 266a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and End >= I->Start so the range overlaps 267a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // but is not entirely contained within the range. 268a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 269a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // See if the range extends the start of the range. In this case, it couldn't 270a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // possibly cause it to join the prior range, because otherwise we would have 271a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // stopped on *it*. 272a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Start < I->Start) { 273a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->Start = Start; 274a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->StartPtr = SI->getPointerOperand(); 275a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 276a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 277a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and Start >= I->Start (so the startpoint 278a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // is in or right at the end of I), and that End >= I->Start. Extend I out to 279a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // End. 280a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (End > I->End) { 281a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = End; 2829c0f146d50ccc3ba780d4854b8e14422430013efNick Lewycky range_iterator NextI = I; 283a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (++NextI != E && End >= NextI->Start) { 284a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Merge the range in. 285a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end()); 286a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextI->End > I->End) 287a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = NextI->End; 288a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.erase(NextI); 289a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson NextI = I; 290a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 291a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 292a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 293a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 294a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 295a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt Pass 296a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 297a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 298a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 299a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 300a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson class VISIBILITY_HIDDEN MemCpyOpt : public FunctionPass { 301a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool runOnFunction(Function &F); 302a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson public: 303a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson static char ID; // Pass identification, replacement for typeid 304ae73dc1448d25b02cabc7c64c86c64371453dda8Dan Gohman MemCpyOpt() : FunctionPass(&ID) {} 305a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 306a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson private: 307a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This transformation requires dominator postdominator info 308a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson virtual void getAnalysisUsage(AnalysisUsage &AU) const { 309a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.setPreservesCFG(); 310a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<DominatorTree>(); 311a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<MemoryDependenceAnalysis>(); 312a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<AliasAnalysis>(); 313a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<AliasAnalysis>(); 314a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<MemoryDependenceAnalysis>(); 315a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 316a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 317a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Helper fuctions 31861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool processStore(StoreInst *SI, BasicBlock::iterator &BBI); 31961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool processMemCpy(MemCpyInst *M); 320f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner bool processMemMove(MemMoveInst *M); 32161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool performCallSlotOptzn(MemCpyInst *cpy, CallInst *C); 322a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool iterateOnFunction(Function &F); 323a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 324a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 325a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson char MemCpyOpt::ID = 0; 326a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 327a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 328a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// createMemCpyOptPass - The public interface to this file... 329a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonFunctionPass *llvm::createMemCpyOptPass() { return new MemCpyOpt(); } 330a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 331a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic RegisterPass<MemCpyOpt> X("memcpyopt", 332a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson "MemCpy Optimization"); 333a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 334a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 335a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 336a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// processStore - When GVN is scanning forward over instructions, we look for 337a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// some other patterns to fold away. In particular, this looks for stores to 338a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// neighboring locations of memory. If it sees enough consequtive ones 339a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// (currently 4) it attempts to merge them together into a memcpy/memset. 34061c6ba85715fdcb66f746678879984151f1e5485Chris Lattnerbool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) { 341a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (SI->isVolatile()) return false; 342a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 343a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // There are two cases that are interesting for this code to handle: memcpy 344a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // and memset. Right now we only handle memset. 345a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 346a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Ensure that the value being stored is something that can be memset'able a 347a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // byte at a time like "0" or "-1" or any width, as well as things like 348a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 0xA0A0A0A0 and 0.0. 349e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson Value *ByteVal = isBytewiseValue(SI->getOperand(0), SI->getContext()); 350a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!ByteVal) 351a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 352a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 3538942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman TargetData *TD = getAnalysisIfAvailable<TargetData>(); 3548942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!TD) return false; 355a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 356a195b7ffd6612a331751c7b6042d5cd921ee586cDan Gohman Module *M = SI->getParent()->getParent()->getParent(); 357a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 358a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Okay, so we now have a single store that can be splatable. Scan to find 359a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // all subsequent stores of the same value to offset from the same pointer. 360a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Join these together into ranges, so we can decide whether contiguous blocks 361a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // are stored. 3628942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman MemsetRanges Ranges(*TD); 363a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 364a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr = SI->getPointerOperand(); 365a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 366a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator BI = SI; 367a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (++BI; !isa<TerminatorInst>(BI); ++BI) { 368a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) { 369a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the call is readnone, ignore it, otherwise bail out. We don't even 370a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // allow readonly here because we don't want something like: 371a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A). 372a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.getModRefBehavior(CallSite::get(BI)) == 373a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::DoesNotAccessMemory) 374a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 375a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 376a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // TODO: If this is a memset, try to join it in. 377a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 378a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 379a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (isa<VAArgInst>(BI) || isa<LoadInst>(BI)) 380a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 381a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 382a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a non-store instruction it is fine, ignore it. 383a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StoreInst *NextStore = dyn_cast<StoreInst>(BI); 384a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore == 0) continue; 385a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 386a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a store, see if we can merge it in. 387a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore->isVolatile()) break; 388a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 389a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this stored value is of the same byte-splattable value. 390e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson if (ByteVal != isBytewiseValue(NextStore->getOperand(0), 391e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson NextStore->getContext())) 392a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 393a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 394a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this store is to a constant offset from the start ptr. 395a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset; 3968942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, *TD)) 397a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 398a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 399a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(Offset, NextStore); 400a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 401a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 402a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have no ranges, then we just had a single store with nothing that 403a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // could be merged in. This is a very common case of course. 404a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Ranges.empty()) 405a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 406a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 407a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we had at least one store that could be merged in, add the starting 408a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // store as well. We try to avoid this unless there is at least something 409a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // interesting as a small compile-time optimization. 410a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(0, SI); 411a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 412a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 413a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Function *MemSetF = 0; 414a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 415a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now that we have full information about ranges, loop over the ranges and 416a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // emit memset's for anything big enough to be worthwhile. 417a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool MadeChange = false; 418a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end(); 419a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) { 420a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const MemsetRange &Range = *I; 421a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 422a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Range.TheStores.size() == 1) continue; 423a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 424a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If it is profitable to lower this range to memset, do so now. 4258942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!Range.isProfitableToUseMemset(*TD)) 426a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 427a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 428a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we do want to transform this! Create a new memset. We put 429a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memset right before the first instruction that isn't part of this 430a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset block. This ensure that the memset is dominated by any addressing 431a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // instruction needed by the start of the block. 432a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator InsertPt = BI; 433a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 434824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner if (MemSetF == 0) { 435f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner const Type *Ty = Type::getInt64Ty(SI->getContext()); 436f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner MemSetF = Intrinsic::getDeclaration(M, Intrinsic::memset, &Ty, 1); 437824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner } 438a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 439a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Get the starting pointer of the block. 440a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr = Range.StartPtr; 441a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 442a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Cast the start ptr to be i8* as memset requires. 4431d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson const Type *i8Ptr = 4441d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson PointerType::getUnqual(Type::getInt8Ty(SI->getContext())); 445a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (StartPtr->getType() != i8Ptr) 446460f656475738d1a95a6be95346908ce1597df25Daniel Dunbar StartPtr = new BitCastInst(StartPtr, i8Ptr, StartPtr->getName(), 447a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson InsertPt); 448a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 449a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *Ops[] = { 450a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr, ByteVal, // Start, value 451e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson // size 4521d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ConstantInt::get(Type::getInt64Ty(SI->getContext()), 4531d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson Range.End-Range.Start), 454e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson // align 4551d0be15f89cb5056e20e2d24faa8d6afb1573bcaOwen Anderson ConstantInt::get(Type::getInt32Ty(SI->getContext()), Range.Alignment) 456a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 457a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *C = CallInst::Create(MemSetF, Ops, Ops+4, "", InsertPt); 458bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner DEBUG(errs() << "Replace stores:\n"; 459a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i) 460bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner errs() << *Range.TheStores[i]; 461bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner errs() << "With: " << *C); C=C; 462a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 463a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Don't invalidate the iterator 464a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson BBI = BI; 465a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 466a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Zap all the stores. 467a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (SmallVector<StoreInst*, 16>::const_iterator SI = Range.TheStores.begin(), 468a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson SE = Range.TheStores.end(); SI != SE; ++SI) 469a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson (*SI)->eraseFromParent(); 470a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++NumMemSetInfer; 471a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MadeChange = true; 472a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 473a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 474a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return MadeChange; 475a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 476a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 477a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 478a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// performCallSlotOptzn - takes a memcpy and a call that it depends on, 479a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// and checks for the possibility of a call slot optimization by having 480a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the call write its result directly into the destination of the memcpy. 481a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool MemCpyOpt::performCallSlotOptzn(MemCpyInst *cpy, CallInst *C) { 482a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The general transformation to keep in mind is 483a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 484a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., src, ...) 485a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 486a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 487a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // -> 488a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 489a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 490a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., dest, ...) 491a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 492a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since moving the memcpy is technically awkward, we additionally check that 493a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // src only holds uninitialized values at the moment of the call, meaning that 494a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy can be discarded rather than moved. 495a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 496a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Deliberately get the source and destination with bitcasts stripped away, 497a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // because we'll need to do type comparisons based on the underlying type. 49861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner Value *cpyDest = cpy->getDest(); 49961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner Value *cpySrc = cpy->getSource(); 500a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson CallSite CS = CallSite::get(C); 501a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 502a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We need to be able to reason about the size of the memcpy, so we require 503a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that it be a constant. 50461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *cpyLength = dyn_cast<ConstantInt>(cpy->getLength()); 505a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!cpyLength) 506a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 507a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 508a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Require that src be an alloca. This simplifies the reasoning considerably. 50961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner AllocaInst *srcAlloca = dyn_cast<AllocaInst>(cpySrc); 510a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcAlloca) 511a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 512a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 513a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that all of src is copied to dest. 51461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner TargetData *TD = getAnalysisIfAvailable<TargetData>(); 5158942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!TD) return false; 516a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 51761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize()); 518a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcArraySize) 519a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 520a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 5218942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman uint64_t srcSize = TD->getTypeAllocSize(srcAlloca->getAllocatedType()) * 522a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcArraySize->getZExtValue(); 523a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 524a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpyLength->getZExtValue() < srcSize) 525a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 526a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 527a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that accessing the first srcSize bytes of dest will not cause a 528a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // trap. Otherwise the transform is invalid since it might cause a trap 529a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to occur earlier than it otherwise would. 53061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (AllocaInst *A = dyn_cast<AllocaInst>(cpyDest)) { 531a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The destination is an alloca. Check it is larger than srcSize. 53261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *destArraySize = dyn_cast<ConstantInt>(A->getArraySize()); 533a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!destArraySize) 534a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 535a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 5368942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman uint64_t destSize = TD->getTypeAllocSize(A->getAllocatedType()) * 537a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson destArraySize->getZExtValue(); 538a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 539a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 540a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 54161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner } else if (Argument *A = dyn_cast<Argument>(cpyDest)) { 542a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the destination is an sret parameter then only accesses that are 543a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // outside of the returned struct type can trap. 544a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!A->hasStructRetAttr()) 545a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 546a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 54761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner const Type *StructTy = cast<PointerType>(A->getType())->getElementType(); 5488942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman uint64_t destSize = TD->getTypeAllocSize(StructTy); 549a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 550a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 551a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 552a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else { 553a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 554a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 555a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 556a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that src is not accessed except via the call and the memcpy. This 557a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // guarantees that it holds only undefined values when passed in (so the final 558a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy can be dropped), that it is not read or written between the call and 559a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy, and that writing beyond the end of it is undefined. 560a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(), 561a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcAlloca->use_end()); 562a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (!srcUseList.empty()) { 56361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner User *UI = srcUseList.back(); 564a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.pop_back(); 565a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 566009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (isa<BitCastInst>(UI)) { 567a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 568a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) 569a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.push_back(*I); 57061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner } else if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(UI)) { 571009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (G->hasAllZeroIndices()) 572009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 573009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson I != E; ++I) 574009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson srcUseList.push_back(*I); 575009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson else 576009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson return false; 577a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (UI != C && UI != cpy) { 578a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 579a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 580a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 581a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 582a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we're changing the parameter to the callsite, we need to make sure 583a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that what would be the new parameter dominates the callsite. 58461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner DominatorTree &DT = getAnalysis<DominatorTree>(); 58561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (Instruction *cpyDestInst = dyn_cast<Instruction>(cpyDest)) 586a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!DT.dominates(cpyDestInst, C)) 587a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 588a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 589a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // In addition to knowing that the call does not access src in some 590a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // unexpected manner, for example via a global, which we deduce from 591a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the use analysis, we also need to know that it does not sneakily 592a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // access dest. We rely on AA to figure this out for us. 59361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 594a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.getModRefInfo(C, cpy->getRawDest(), srcSize) != 595a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoModRef) 596a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 597a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 598a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All the checks have passed, so do the transformation. 59912cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson bool changedArgument = false; 600a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0; i < CS.arg_size(); ++i) 601009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (CS.getArgument(i)->stripPointerCasts() == cpySrc) { 602a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpySrc->getType() != cpyDest->getType()) 6037cbd8a3e92221437048b484d5ef9c0a22d0f8c58Gabor Greif cpyDest = CastInst::CreatePointerCast(cpyDest, cpySrc->getType(), 604a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cpyDest->getName(), C); 60512cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson changedArgument = true; 60661c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (CS.getArgument(i)->getType() == cpyDest->getType()) 607009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.setArgument(i, cpyDest); 60861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner else 60961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner CS.setArgument(i, CastInst::CreatePointerCast(cpyDest, 61061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner CS.getArgument(i)->getType(), cpyDest->getName(), C)); 611a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 612a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 61312cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson if (!changedArgument) 61412cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson return false; 61512cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson 616a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Drop any cached information about the call, because we may have changed 617a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // its dependence information by changing its parameter. 61861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MemoryDependenceAnalysis &MD = getAnalysis<MemoryDependenceAnalysis>(); 6194f8c18c7c757875cfa45383e7cf33d65d2c4d564Chris Lattner MD.removeInstruction(C); 620a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 621a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Remove the memcpy 622a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MD.removeInstruction(cpy); 623a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson cpy->eraseFromParent(); 624a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson NumMemCpyInstr++; 625a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 626a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 627a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 628a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 629a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which 630a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be 631a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// a memcpy from X to Z (or potentially a memmove, depending on circumstances). 632a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// This allows later passes to remove the first memcpy altogether. 63361c6ba85715fdcb66f746678879984151f1e5485Chris Lattnerbool MemCpyOpt::processMemCpy(MemCpyInst *M) { 63461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MemoryDependenceAnalysis &MD = getAnalysis<MemoryDependenceAnalysis>(); 635a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 636a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // The are two possible optimizations we can do for memcpy: 63761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner // a) memcpy-memcpy xform which exposes redundance for DSE. 63861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner // b) call-memcpy xform for return slot optimization. 6394c724006256032e827177afeae04ea62436796e7Chris Lattner MemDepResult dep = MD.getDependency(M); 640b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner if (!dep.isClobber()) 641a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson return false; 642b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner if (!isa<MemCpyInst>(dep.getInst())) { 64361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (CallInst *C = dyn_cast<CallInst>(dep.getInst())) 6449dcace3cafb4da5c3d94f3b89e54ea0d7164a286Owen Anderson return performCallSlotOptzn(M, C); 645b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner return false; 6469dcace3cafb4da5c3d94f3b89e54ea0d7164a286Owen Anderson } 647a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 64861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MemCpyInst *MDep = cast<MemCpyInst>(dep.getInst()); 649a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 650a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can only transforms memcpy's where the dest of one is the source of the 651a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // other 652a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (M->getSource() != MDep->getDest()) 653a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 654a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 655a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Second, the length of the memcpy's must be the same, or the preceeding one 656a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // must be larger than the following one. 65761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *C1 = dyn_cast<ConstantInt>(MDep->getLength()); 65861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *C2 = dyn_cast<ConstantInt>(M->getLength()); 659a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!C1 || !C2) 660a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 661a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 662a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t DepSize = C1->getValue().getZExtValue(); 663a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t CpySize = C2->getValue().getZExtValue(); 664a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 665a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (DepSize < CpySize) 666a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 667a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 668a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Finally, we have to make sure that the dest of the second does not 669a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // alias the source of the first 67061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 671a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) != 672a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoAlias) 673a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 674a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) != 675a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoAlias) 676a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 677a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize) 678a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson != AliasAnalysis::NoAlias) 679a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 680a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 681a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If all checks passed, then we can transform these memcpy's 682f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner const Type *Ty = M->getLength()->getType(); 68361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner Function *MemCpyFun = Intrinsic::getDeclaration( 684a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson M->getParent()->getParent()->getParent(), 685f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner M->getIntrinsicID(), &Ty, 1); 686a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 687dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner Value *Args[4] = { 688dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner M->getRawDest(), MDep->getRawSource(), M->getLength(), M->getAlignmentCst() 689dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner }; 690a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 69161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner CallInst *C = CallInst::Create(MemCpyFun, Args, Args+4, "", M); 692a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 69302e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson 69402e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // If C and M don't interfere, then this is a valid transformation. If they 69502e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // did, this would mean that the two sources overlap, which would be bad. 69639f372e23e49cecb8db2eb7120eb331173e50c74Chris Lattner if (MD.getDependency(C) == dep) { 6974f8c18c7c757875cfa45383e7cf33d65d2c4d564Chris Lattner MD.removeInstruction(M); 698a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson M->eraseFromParent(); 69902e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson NumMemCpyInstr++; 700a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 701a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 702a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 70302e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // Otherwise, there was no point in doing this, so we remove the call we 70402e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // inserted and act like nothing happened. 705a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MD.removeInstruction(C); 706a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson C->eraseFromParent(); 70702e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson return false; 708a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 709a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 710f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner/// processMemMove - Transforms memmove calls to memcpy calls when the src/dst 711f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner/// are guaranteed not to alias. 712f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattnerbool MemCpyOpt::processMemMove(MemMoveInst *M) { 713f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 714f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 715f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // If the memmove is a constant size, use it for the alias query, this allows 716f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // us to optimize things like: memmove(P, P+64, 64); 717f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner uint64_t MemMoveSize = ~0ULL; 718f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner if (ConstantInt *Len = dyn_cast<ConstantInt>(M->getLength())) 719f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner MemMoveSize = Len->getZExtValue(); 720f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 721f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // See if the pointers alias. 722f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner if (AA.alias(M->getRawDest(), MemMoveSize, M->getRawSource(), MemMoveSize) != 723f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner AliasAnalysis::NoAlias) 724f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner return false; 725f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 726f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner DEBUG(errs() << "MemCpyOpt: Optimizing memmove -> memcpy: " << *M << "\n"); 727f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 728f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // If not, then we know we can transform this. 729f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner Module *Mod = M->getParent()->getParent()->getParent(); 730f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner const Type *Ty = M->getLength()->getType(); 731f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner M->setOperand(0, Intrinsic::getDeclaration(Mod, Intrinsic::memcpy, &Ty, 1)); 732f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 733f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // MemDep may have over conservative information about this instruction, just 734f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // conservatively flush it from the cache. 735f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner getAnalysis<MemoryDependenceAnalysis>().removeInstruction(M); 736f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner return true; 737f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner} 738f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 739f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 74061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// MemCpyOpt::iterateOnFunction - Executes one iteration of GVN. 741a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemCpyOpt::iterateOnFunction(Function &F) { 74261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool MadeChange = false; 743a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 74461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner // Walk all instruction in the function. 745a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) { 746a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); 747a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BI != BE;) { 74861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner // Avoid invalidating the iterator. 74961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner Instruction *I = BI++; 750a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 751a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson if (StoreInst *SI = dyn_cast<StoreInst>(I)) 75261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MadeChange |= processStore(SI, BI); 75361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner else if (MemCpyInst *M = dyn_cast<MemCpyInst>(I)) 75461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MadeChange |= processMemCpy(M); 755f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner else if (MemMoveInst *M = dyn_cast<MemMoveInst>(I)) { 756f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner if (processMemMove(M)) { 757f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner --BI; // Reprocess the new memcpy. 758f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner MadeChange = true; 759f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner } 760f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner } 761a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 762a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 763a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 76461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner return MadeChange; 765a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 76661c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 76761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// MemCpyOpt::runOnFunction - This is the main transformation entry point for a 76861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// function. 76961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// 77061c6ba85715fdcb66f746678879984151f1e5485Chris Lattnerbool MemCpyOpt::runOnFunction(Function &F) { 77161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool MadeChange = false; 77261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner while (1) { 77361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (!iterateOnFunction(F)) 77461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner break; 77561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MadeChange = true; 77661c6ba85715fdcb66f746678879984151f1e5485Chris Lattner } 77761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 77861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner return MadeChange; 77961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner} 78061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 78161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 78261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 783