MemCpyOptimizer.cpp revision e922c0201916e0b980ab3cfe91e1413e68d55647
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" 27a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Target/TargetData.h" 28a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include <list> 29a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonusing namespace llvm; 30a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 31a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonSTATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted"); 32a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonSTATISTIC(NumMemSetInfer, "Number of memsets inferred"); 33a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 34a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// isBytewiseValue - If the specified value can be set by repeating the same 35a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// byte in memory, return the i8 value that it is represented with. This is 36a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// true for all i8 values obviously, but is also true for i32 0, i32 -1, 37a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated 38a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// byte store (e.g. i16 0x1234), return null. 39e922c0201916e0b980ab3cfe91e1413e68d55647Owen Andersonstatic Value *isBytewiseValue(Value *V, LLVMContext& Context) { 40a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All byte-wide stores are splatable, even of arbitrary variables. 41a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (V->getType() == Type::Int8Ty) return V; 42a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 43a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Constant float and double values can be handled as integer values if the 44a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // corresponding integer value is "byteable". An important case is 0.0. 45a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { 46a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (CFP->getType() == Type::FloatTy) 47e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson V = Context.getConstantExprBitCast(CFP, Type::Int32Ty); 48a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (CFP->getType() == Type::DoubleTy) 49e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson V = Context.getConstantExprBitCast(CFP, Type::Int64Ty); 50a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Don't handle long double formats, which have strange constraints. 51a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 52a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 53a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can handle constant integers that are power of two in size and a 54a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // multiple of 8 bits. 55a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { 56a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Width = CI->getBitWidth(); 57a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isPowerOf2_32(Width) && Width > 8) { 58a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can handle this value if the recursive binary decomposition is the 59a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // same at all levels. 60a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson APInt Val = CI->getValue(); 61a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson APInt Val2; 62a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (Val.getBitWidth() != 8) { 63a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NextWidth = Val.getBitWidth()/2; 64a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val2 = Val.lshr(NextWidth); 65a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val2.trunc(Val.getBitWidth()/2); 66a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Val.trunc(Val.getBitWidth()/2); 67a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 68a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the top/bottom halves aren't the same, reject it. 69a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Val != Val2) 70a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return 0; 71a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 72e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson return Context.getConstantInt(Val); 73a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 74a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 75a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 76a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Conceptually, we could handle things like: 77a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %a = zext i8 %X to i16 78a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %b = shl i16 %a, 8 79a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // %c = or i16 %a, %b 80a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // but until there is an example that actually needs this, it doesn't seem 81a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // worth worrying about. 82a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return 0; 83a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 84a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 85a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic int64_t GetOffsetFromIndex(const GetElementPtrInst *GEP, unsigned Idx, 86a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool &VariableIdxFound, TargetData &TD) { 87a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Skip over the first indices. 88a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson gep_type_iterator GTI = gep_type_begin(GEP); 89a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 1; i != Idx; ++i, ++GTI) 90a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /*skip along*/; 91a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 92a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Compute the offset implied by the rest of the indices. 93a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset = 0; 94a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { 95a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i)); 96a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (OpC == 0) 97a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return VariableIdxFound = true; 98a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (OpC->isZero()) continue; // No offset. 99a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 100a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Handle struct indices, which add their field offset to the pointer. 101a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (const StructType *STy = dyn_cast<StructType>(*GTI)) { 102a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); 103a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 104a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 105a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 106a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we have a sequential type like an array or vector. Multiply 107a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the index by the ElementSize. 108777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); 109a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset += Size*OpC->getSExtValue(); 110a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 111a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 112a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return Offset; 113a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 114a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 115a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// IsPointerOffset - Return true if Ptr1 is provably equal to Ptr2 plus a 116a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// constant offset, and return that constant offset. For example, Ptr1 might 117a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// be &A[42], and Ptr2 might be &A[40]. In this case offset would be -8. 118a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstatic bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset, 119a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD) { 120a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical 121a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // base. After that base, they may have some number of common (and 122a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // potentially variable) indices. After that they handle some constant 123a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // offset, which determines their offset from each other. At this point, we 124a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // handle no other case. 125a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(Ptr1); 126a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(Ptr2); 127a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0)) 128a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 129a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 130a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Skip any common indices and track the GEP types. 131a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Idx = 1; 132a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx) 133a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx)) 134a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 135a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 136a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool VariableIdxFound = false; 137a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, TD); 138a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, TD); 139a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (VariableIdxFound) return false; 140a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 141a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Offset = Offset2-Offset1; 142a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 143a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 144a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 145a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 146a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// MemsetRange - Represents a range of memset'd bytes with the ByteVal value. 147a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// This allows us to analyze stores like: 148a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+1 149a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+0 150a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+3 151a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// store 0 -> P+2 152a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// which sometimes happens with stores to arrays of structs etc. When we see 153a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the first store, we make a range [1, 2). The second store extends the range 154a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// to [0, 2). The third makes a new range [2, 3). The fourth store joins the 155a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// two ranges into [0, 3) which is memset'able. 156a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 157a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonstruct MemsetRange { 158a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Start/End - A semi range that describes the span that this range covers. 159a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The range is closed at the start and open at the end: [Start, End). 160a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Start, End; 161a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 162a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// StartPtr - The getelementptr instruction that points to the start of the 163a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// range. 164a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr; 165a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 166a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// Alignment - The known alignment of the first store. 167a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Alignment; 168a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 169a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// TheStores - The actual stores that make up this range. 170a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<StoreInst*, 16> TheStores; 171a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 172a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool isProfitableToUseMemset(const TargetData &TD) const; 173a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 174a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson}; 175a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} // end anon namespace 176a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 177a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const { 178a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we found more than 8 stores to merge or 64 bytes, use memset. 179a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (TheStores.size() >= 8 || End-Start >= 64) return true; 180a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 181a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Assume that the code generator is capable of merging pairs of stores 182a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // together if it wants to. 183a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (TheStores.size() <= 2) return false; 184a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 185a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have fewer than 8 stores, it can still be worthwhile to do this. 186a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // For example, merging 4 i8 stores into an i32 store is useful almost always. 187a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // However, merging 2 32-bit stores isn't useful on a 32-bit architecture (the 188a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset will be split into 2 32-bit stores anyway) and doing so can 189a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // pessimize the llvm optimizer. 190a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 191a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we don't have perfect knowledge here, make some assumptions: assume 192a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the maximum GPR width is the same size as the pointer size and assume that 193a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // this width can be stored. If so, check to see whether we will end up 194a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // actually reducing the number of stores used. 195a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned Bytes = unsigned(End-Start); 196a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NumPointerStores = Bytes/TD.getPointerSize(); 197a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 198a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Assume the remaining bytes if any are done a byte at a time. 199a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson unsigned NumByteStores = Bytes - NumPointerStores*TD.getPointerSize(); 200a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 201a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we will reduce the # stores (according to this heuristic), do the 202a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32 203a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // etc. 204a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return TheStores.size() > NumPointerStores+NumByteStores; 205a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 206a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 207a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 208a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 209a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonclass MemsetRanges { 210a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// Ranges - A sorted list of the memset ranges. We use std::list here 211a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson /// because each element is relatively large and expensive to copy. 212a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson std::list<MemsetRange> Ranges; 213a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson typedef std::list<MemsetRange>::iterator range_iterator; 214a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD; 215a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonpublic: 216a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRanges(TargetData &td) : TD(td) {} 217a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 218a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson typedef std::list<MemsetRange>::const_iterator const_iterator; 219a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const_iterator begin() const { return Ranges.begin(); } 220a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const_iterator end() const { return Ranges.end(); } 221a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool empty() const { return Ranges.empty(); } 222a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 223a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson void addStore(int64_t OffsetFromFirst, StoreInst *SI); 224a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson}; 225a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 226a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} // end anon namespace 227a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 228a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 229a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// addStore - Add a new store to the MemsetRanges data structure. This adds a 230a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// new range for the specified store at the specified offset, merging into 231a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// existing ranges as appropriate. 232a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonvoid MemsetRanges::addStore(int64_t Start, StoreInst *SI) { 233a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t End = Start+TD.getTypeStoreSize(SI->getOperand(0)->getType()); 234a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 235a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Do a linear search of the ranges to see if this can be joined and/or to 236a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // find the insertion point in the list. We keep the ranges sorted for 237a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // simplicity here. This is a linear search of a linked list, which is ugly, 238a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // however the number of ranges is limited, so this won't get crazy slow. 239a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson range_iterator I = Ranges.begin(), E = Ranges.end(); 240a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 241a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (I != E && Start > I->End) 242a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++I; 243a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 244a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We now know that I == E, in which case we didn't find anything to merge 245a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // with, or that Start <= I->End. If End < I->Start or I == E, then we need 246a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to insert a new range. Handle this now. 247a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (I == E || End < I->Start) { 248a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRange &R = *Ranges.insert(I, MemsetRange()); 249a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.Start = Start; 250a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.End = End; 251a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.StartPtr = SI->getPointerOperand(); 252a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.Alignment = SI->getAlignment(); 253a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson R.TheStores.push_back(SI); 254a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return; 255a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 256a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 257a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This store overlaps with I, add it. 258a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.push_back(SI); 259a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 260a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // At this point, we may have an interval that completely contains our store. 261a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If so, just add it to the interval and return. 262a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (I->Start <= Start && I->End >= End) 263a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return; 264a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 265a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and End >= I->Start so the range overlaps 266a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // but is not entirely contained within the range. 267a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 268a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // See if the range extends the start of the range. In this case, it couldn't 269a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // possibly cause it to join the prior range, because otherwise we would have 270a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // stopped on *it*. 271a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Start < I->Start) { 272a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->Start = Start; 273a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->StartPtr = SI->getPointerOperand(); 274a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 275a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 276a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and Start >= I->Start (so the startpoint 277a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // is in or right at the end of I), and that End >= I->Start. Extend I out to 278a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // End. 279a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (End > I->End) { 280a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = End; 2819c0f146d50ccc3ba780d4854b8e14422430013efNick Lewycky range_iterator NextI = I; 282a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (++NextI != E && End >= NextI->Start) { 283a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Merge the range in. 284a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end()); 285a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextI->End > I->End) 286a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = NextI->End; 287a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.erase(NextI); 288a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson NextI = I; 289a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 290a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 291a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 292a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 293a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 294a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt Pass 295a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 296a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 297a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 298a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 299a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson class VISIBILITY_HIDDEN MemCpyOpt : public FunctionPass { 300a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool runOnFunction(Function &F); 301a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson public: 302a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson static char ID; // Pass identification, replacement for typeid 303ae73dc1448d25b02cabc7c64c86c64371453dda8Dan Gohman MemCpyOpt() : FunctionPass(&ID) {} 304a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 305a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson private: 306a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This transformation requires dominator postdominator info 307a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson virtual void getAnalysisUsage(AnalysisUsage &AU) const { 308a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.setPreservesCFG(); 309a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<DominatorTree>(); 310a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<MemoryDependenceAnalysis>(); 311a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<AliasAnalysis>(); 312a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<TargetData>(); 313a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<AliasAnalysis>(); 314a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<MemoryDependenceAnalysis>(); 315a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<TargetData>(); 316a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 317a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 318a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Helper fuctions 319a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson bool processStore(StoreInst *SI, BasicBlock::iterator& BBI); 320a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson bool processMemCpy(MemCpyInst* M); 321a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 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. 340a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool 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 353a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData &TD = getAnalysis<TargetData>(); 354a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 355a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 356a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Okay, so we now have a single store that can be splatable. Scan to find 357a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // all subsequent stores of the same value to offset from the same pointer. 358a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Join these together into ranges, so we can decide whether contiguous blocks 359a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // are stored. 360a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemsetRanges Ranges(TD); 361a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 362a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr = SI->getPointerOperand(); 363a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 364a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator BI = SI; 365a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (++BI; !isa<TerminatorInst>(BI); ++BI) { 366a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) { 367a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the call is readnone, ignore it, otherwise bail out. We don't even 368a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // allow readonly here because we don't want something like: 369a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A). 370a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.getModRefBehavior(CallSite::get(BI)) == 371a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::DoesNotAccessMemory) 372a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 373a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 374a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // TODO: If this is a memset, try to join it in. 375a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 376a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 377a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (isa<VAArgInst>(BI) || isa<LoadInst>(BI)) 378a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 379a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 380a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a non-store instruction it is fine, ignore it. 381a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StoreInst *NextStore = dyn_cast<StoreInst>(BI); 382a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore == 0) continue; 383a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 384a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a store, see if we can merge it in. 385a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore->isVolatile()) break; 386a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 387a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this stored value is of the same byte-splattable value. 388e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson if (ByteVal != isBytewiseValue(NextStore->getOperand(0), 389e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson NextStore->getContext())) 390a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 391a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 392a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this store is to a constant offset from the start ptr. 393a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset; 394a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, TD)) 395a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 396a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 397a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(Offset, NextStore); 398a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 399a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 400a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have no ranges, then we just had a single store with nothing that 401a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // could be merged in. This is a very common case of course. 402a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Ranges.empty()) 403a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 404a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 405a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we had at least one store that could be merged in, add the starting 406a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // store as well. We try to avoid this unless there is at least something 407a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // interesting as a small compile-time optimization. 408a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(0, SI); 409a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 410a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 411a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Function *MemSetF = 0; 412a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 413a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now that we have full information about ranges, loop over the ranges and 414a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // emit memset's for anything big enough to be worthwhile. 415a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool MadeChange = false; 416a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end(); 417a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) { 418a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const MemsetRange &Range = *I; 419a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 420a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Range.TheStores.size() == 1) continue; 421a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 422a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If it is profitable to lower this range to memset, do so now. 423a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!Range.isProfitableToUseMemset(TD)) 424a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 425a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 426a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we do want to transform this! Create a new memset. We put 427a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memset right before the first instruction that isn't part of this 428a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset block. This ensure that the memset is dominated by any addressing 429a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // instruction needed by the start of the block. 430a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator InsertPt = BI; 431a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 432824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner if (MemSetF == 0) { 433824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner const Type *Tys[] = {Type::Int64Ty}; 434a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemSetF = Intrinsic::getDeclaration(SI->getParent()->getParent() 435824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner ->getParent(), Intrinsic::memset, 436824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner Tys, 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. 443e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson const Type *i8Ptr = SI->getContext().getPointerTypeUnqual(Type::Int8Ty); 444a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (StartPtr->getType() != i8Ptr) 445a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr = new BitCastInst(StartPtr, i8Ptr, StartPtr->getNameStart(), 446a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson InsertPt); 447a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 448a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *Ops[] = { 449a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr, ByteVal, // Start, value 450e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson // size 451e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson SI->getContext().getConstantInt(Type::Int64Ty, Range.End-Range.Start), 452e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson // align 453e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson SI->getContext().getConstantInt(Type::Int32Ty, Range.Alignment) 454a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 455a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *C = CallInst::Create(MemSetF, Ops, Ops+4, "", InsertPt); 456a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson DEBUG(cerr << "Replace stores:\n"; 457a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i) 458a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cerr << *Range.TheStores[i]; 459a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cerr << "With: " << *C); C=C; 460a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 461a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Don't invalidate the iterator 462a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson BBI = BI; 463a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 464a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Zap all the stores. 465a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (SmallVector<StoreInst*, 16>::const_iterator SI = Range.TheStores.begin(), 466a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson SE = Range.TheStores.end(); SI != SE; ++SI) 467a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson (*SI)->eraseFromParent(); 468a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++NumMemSetInfer; 469a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MadeChange = true; 470a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 471a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 472a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return MadeChange; 473a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 474a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 475a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 476a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// performCallSlotOptzn - takes a memcpy and a call that it depends on, 477a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// and checks for the possibility of a call slot optimization by having 478a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the call write its result directly into the destination of the memcpy. 479a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool MemCpyOpt::performCallSlotOptzn(MemCpyInst *cpy, CallInst *C) { 480a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The general transformation to keep in mind is 481a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 482a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., src, ...) 483a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 484a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 485a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // -> 486a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 487a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 488a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., dest, ...) 489a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 490a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since moving the memcpy is technically awkward, we additionally check that 491a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // src only holds uninitialized values at the moment of the call, meaning that 492a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy can be discarded rather than moved. 493a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 494a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Deliberately get the source and destination with bitcasts stripped away, 495a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // because we'll need to do type comparisons based on the underlying type. 496a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value* cpyDest = cpy->getDest(); 497a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value* cpySrc = cpy->getSource(); 498a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson CallSite CS = CallSite::get(C); 499a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 500a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We need to be able to reason about the size of the memcpy, so we require 501a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that it be a constant. 502a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* cpyLength = dyn_cast<ConstantInt>(cpy->getLength()); 503a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!cpyLength) 504a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 505a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 506a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Require that src be an alloca. This simplifies the reasoning considerably. 507a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AllocaInst* srcAlloca = dyn_cast<AllocaInst>(cpySrc); 508a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcAlloca) 509a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 510a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 511a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that all of src is copied to dest. 512a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson TargetData& TD = getAnalysis<TargetData>(); 513a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 514a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize()); 515a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcArraySize) 516a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 517a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 518777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t srcSize = TD.getTypeAllocSize(srcAlloca->getAllocatedType()) * 519a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcArraySize->getZExtValue(); 520a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 521a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpyLength->getZExtValue() < srcSize) 522a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 523a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 524a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that accessing the first srcSize bytes of dest will not cause a 525a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // trap. Otherwise the transform is invalid since it might cause a trap 526a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to occur earlier than it otherwise would. 527a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AllocaInst* A = dyn_cast<AllocaInst>(cpyDest)) { 528a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The destination is an alloca. Check it is larger than srcSize. 529a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* destArraySize = dyn_cast<ConstantInt>(A->getArraySize()); 530a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!destArraySize) 531a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 532a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 533777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t destSize = TD.getTypeAllocSize(A->getAllocatedType()) * 534a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson destArraySize->getZExtValue(); 535a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 536a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 537a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 538a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (Argument* A = dyn_cast<Argument>(cpyDest)) { 539a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the destination is an sret parameter then only accesses that are 540a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // outside of the returned struct type can trap. 541a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!A->hasStructRetAttr()) 542a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 543a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 544a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const Type* StructTy = cast<PointerType>(A->getType())->getElementType(); 545777d2306b36816a53bc1ae1244c0dc7d998ae691Duncan Sands uint64_t destSize = TD.getTypeAllocSize(StructTy); 546a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 547a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 548a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 549a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else { 550a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 551a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 552a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 553a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that src is not accessed except via the call and the memcpy. This 554a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // guarantees that it holds only undefined values when passed in (so the final 555a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy can be dropped), that it is not read or written between the call and 556a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy, and that writing beyond the end of it is undefined. 557a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(), 558a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcAlloca->use_end()); 559a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (!srcUseList.empty()) { 560a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson User* UI = srcUseList.back(); 561a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.pop_back(); 562a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 563009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (isa<BitCastInst>(UI)) { 564a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 565a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) 566a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.push_back(*I); 567009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson } else if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(UI)) { 568009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (G->hasAllZeroIndices()) 569009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 570009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson I != E; ++I) 571009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson srcUseList.push_back(*I); 572009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson else 573009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson return false; 574a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (UI != C && UI != cpy) { 575a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 576a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 577a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 578a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 579a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we're changing the parameter to the callsite, we need to make sure 580a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that what would be the new parameter dominates the callsite. 581a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson DominatorTree& DT = getAnalysis<DominatorTree>(); 582a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Instruction* cpyDestInst = dyn_cast<Instruction>(cpyDest)) 583a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!DT.dominates(cpyDestInst, C)) 584a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 585a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 586a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // In addition to knowing that the call does not access src in some 587a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // unexpected manner, for example via a global, which we deduce from 588a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the use analysis, we also need to know that it does not sneakily 589a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // access dest. We rely on AA to figure this out for us. 590a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis& AA = getAnalysis<AliasAnalysis>(); 591a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.getModRefInfo(C, cpy->getRawDest(), srcSize) != 592a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoModRef) 593a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 594a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 595a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All the checks have passed, so do the transformation. 59612cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson bool changedArgument = false; 597a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0; i < CS.arg_size(); ++i) 598009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (CS.getArgument(i)->stripPointerCasts() == cpySrc) { 599a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpySrc->getType() != cpyDest->getType()) 6007cbd8a3e92221437048b484d5ef9c0a22d0f8c58Gabor Greif cpyDest = CastInst::CreatePointerCast(cpyDest, cpySrc->getType(), 601a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cpyDest->getName(), C); 60212cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson changedArgument = true; 603009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (CS.getArgument(i)->getType() != cpyDest->getType()) 604009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.setArgument(i, CastInst::CreatePointerCast(cpyDest, 605009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.getArgument(i)->getType(), cpyDest->getName(), C)); 606009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson else 607009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.setArgument(i, cpyDest); 608a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 609a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 61012cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson if (!changedArgument) 61112cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson return false; 61212cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson 613a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Drop any cached information about the call, because we may have changed 614a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // its dependence information by changing its parameter. 615a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>(); 6164f8c18c7c757875cfa45383e7cf33d65d2c4d564Chris Lattner MD.removeInstruction(C); 617a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 618a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Remove the memcpy 619a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MD.removeInstruction(cpy); 620a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson cpy->eraseFromParent(); 621a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson NumMemCpyInstr++; 622a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 623a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 624a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 625a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 626a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which 627a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be 628a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// a memcpy from X to Z (or potentially a memmove, depending on circumstances). 629a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// This allows later passes to remove the first memcpy altogether. 630a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Andersonbool MemCpyOpt::processMemCpy(MemCpyInst* M) { 631a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>(); 632a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 633a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // The are two possible optimizations we can do for memcpy: 634a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // a) memcpy-memcpy xform which exposes redundance for DSE 635a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // b) call-memcpy xform for return slot optimization 6364c724006256032e827177afeae04ea62436796e7Chris Lattner MemDepResult dep = MD.getDependency(M); 637b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner if (!dep.isClobber()) 638a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson return false; 639b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner if (!isa<MemCpyInst>(dep.getInst())) { 6404c724006256032e827177afeae04ea62436796e7Chris Lattner if (CallInst* C = dyn_cast<CallInst>(dep.getInst())) 6419dcace3cafb4da5c3d94f3b89e54ea0d7164a286Owen Anderson return performCallSlotOptzn(M, C); 642b51deb929ca95ce62e622b0475a05d83f26ab04dChris Lattner return false; 6439dcace3cafb4da5c3d94f3b89e54ea0d7164a286Owen Anderson } 644a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 6454c724006256032e827177afeae04ea62436796e7Chris Lattner MemCpyInst* MDep = cast<MemCpyInst>(dep.getInst()); 646a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 647a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can only transforms memcpy's where the dest of one is the source of the 648a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // other 649a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (M->getSource() != MDep->getDest()) 650a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 651a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 652a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Second, the length of the memcpy's must be the same, or the preceeding one 653a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // must be larger than the following one. 654a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* C1 = dyn_cast<ConstantInt>(MDep->getLength()); 655a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ConstantInt* C2 = dyn_cast<ConstantInt>(M->getLength()); 656a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!C1 || !C2) 657a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 658a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 659a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t DepSize = C1->getValue().getZExtValue(); 660a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t CpySize = C2->getValue().getZExtValue(); 661a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 662a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (DepSize < CpySize) 663a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 664a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 665a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Finally, we have to make sure that the dest of the second does not 666a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // alias the source of the first 667a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis& AA = getAnalysis<AliasAnalysis>(); 668a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) != 669a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoAlias) 670a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 671a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) != 672a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoAlias) 673a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 674a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize) 675a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson != AliasAnalysis::NoAlias) 676a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 677a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 678a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If all checks passed, then we can transform these memcpy's 679824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner const Type *Tys[1]; 680824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner Tys[0] = M->getLength()->getType(); 681a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Function* MemCpyFun = Intrinsic::getDeclaration( 682a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson M->getParent()->getParent()->getParent(), 683824b958e6fb1236e92e4d07f3acf18fca107cdc0Chris Lattner M->getIntrinsicID(), Tys, 1); 684a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 685dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner Value *Args[4] = { 686dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner M->getRawDest(), MDep->getRawSource(), M->getLength(), M->getAlignmentCst() 687dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner }; 688a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 689dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner CallInst* C = CallInst::Create(MemCpyFun, Args, Args+4, "", M); 690a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 69102e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson 69202e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // If C and M don't interfere, then this is a valid transformation. If they 69302e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // did, this would mean that the two sources overlap, which would be bad. 69439f372e23e49cecb8db2eb7120eb331173e50c74Chris Lattner if (MD.getDependency(C) == dep) { 6954f8c18c7c757875cfa45383e7cf33d65d2c4d564Chris Lattner MD.removeInstruction(M); 696a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson M->eraseFromParent(); 69702e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson NumMemCpyInstr++; 698a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 699a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 700a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 70102e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // Otherwise, there was no point in doing this, so we remove the call we 70202e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson // inserted and act like nothing happened. 703a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MD.removeInstruction(C); 704a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson C->eraseFromParent(); 70502e9988020acb3e8b0271aa9ebc7c8e770c8a85fOwen Anderson return false; 706a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 707a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 708a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt::runOnFunction - This is the main transformation entry point for a 709a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// function. 710a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 711a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemCpyOpt::runOnFunction(Function& F) { 712a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 713a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool changed = false; 714a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool shouldContinue = true; 715a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 716a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (shouldContinue) { 717a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson shouldContinue = iterateOnFunction(F); 718a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson changed |= shouldContinue; 719a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 720a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 721a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return changed; 722a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 723a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 724a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 725a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt::iterateOnFunction - Executes one iteration of GVN 726a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemCpyOpt::iterateOnFunction(Function &F) { 727a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool changed_function = false; 728a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 729a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Walk all instruction in the function 730a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) { 731a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); 732a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BI != BE;) { 733a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Avoid invalidating the iterator 734a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson Instruction* I = BI++; 735a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 736a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson if (StoreInst *SI = dyn_cast<StoreInst>(I)) 737a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson changed_function |= processStore(SI, BI); 738529bd53411c6f583fd8ed435adf4c0f923d185fdTorok Edwin else if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) { 739a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson changed_function |= processMemCpy(M); 740a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson } 741a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 742a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 743a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 744a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return changed_function; 745a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 746