MemCpyOptimizer.cpp revision 8fdca6a8738c1ad7091137688ee48c9e623b75bb
1a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===- MemCpyOptimizer.cpp - Optimize use of memcpy and friends -----------===// 2a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 3a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// The LLVM Compiler Infrastructure 4a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 5a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// This file is distributed under the University of Illinois Open Source 6a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// License. See LICENSE.TXT for details. 7a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 8a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 9a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 10a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// This pass performs various transformations related to eliminating memcpy 11a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// calls, or transforming sets of stores into memset's. 12a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// 13a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 14a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 15a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#define DEBUG_TYPE "memcpyopt" 16a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Transforms/Scalar.h" 17a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/IntrinsicInst.h" 18a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Instructions.h" 19a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/ADT/SmallVector.h" 20a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/ADT/Statistic.h" 21a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/Dominators.h" 22a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/AliasAnalysis.h" 23a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Analysis/MemoryDependenceAnalysis.h" 24a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Support/Debug.h" 25a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson#include "llvm/Support/GetElementPtrTypeIterator.h" 26bdff548e4dd577a72094d57b282de4e765643b96Chris Lattner#include "llvm/Support/raw_ostream.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"); 3305cd03b33559732f8ed55e5ff7554fd06d59eb6aDuncan SandsSTATISTIC(NumMoveToCpy, "Number of memmoves converted to memcpy"); 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. 40cf0fe8d813727383d630055bb9d1cde21b00b7e7Chris Lattnerstatic Value *isBytewiseValue(Value *V) { 41a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All byte-wide stores are splatable, even of arbitrary variables. 42b0bc6c361da9009e8414efde317d9bbff755f6c0Duncan Sands if (V->getType()->isIntegerTy(8)) 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)) { 47cf0fe8d813727383d630055bb9d1cde21b00b7e7Chris Lattner if (CFP->getType()->isFloatTy()) 487a0b4fdd143a8333453dbfa1a85af641c98b5ca4Chris Lattner V = ConstantExpr::getBitCast(CFP, Type::getInt32Ty(V->getContext())); 49cf0fe8d813727383d630055bb9d1cde21b00b7e7Chris Lattner if (CFP->getType()->isDoubleTy()) 507a0b4fdd143a8333453dbfa1a85af641c98b5ca4Chris Lattner V = ConstantExpr::getBitCast(CFP, Type::getInt64Ty(V->getContext())); 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); 6640f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad Val2 = Val2.trunc(Val.getBitWidth()/2); 6740f8f6264d5af2c38e797e0dc59827cd231e8ff7Jay Foad Val = 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 } 737a0b4fdd143a8333453dbfa1a85af641c98b5ca4Chris Lattner return ConstantInt::get(V->getContext(), 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(); 275264d245851173bbace9281a2378a6cc51162b030Dan Gohman I->Alignment = SI->getAlignment(); 276a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 277a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 278a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now we know that Start <= I->End and Start >= I->Start (so the startpoint 279a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // is in or right at the end of I), and that End >= I->Start. Extend I out to 280a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // End. 281a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (End > I->End) { 282a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = End; 2839c0f146d50ccc3ba780d4854b8e14422430013efNick Lewycky range_iterator NextI = I; 284a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (++NextI != E && End >= NextI->Start) { 285a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Merge the range in. 286a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end()); 287a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextI->End > I->End) 288a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I->End = NextI->End; 289a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.erase(NextI); 290a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson NextI = I; 291a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 292a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 293a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 294a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 295a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 296a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// MemCpyOpt Pass 297a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson//===----------------------------------------------------------------------===// 298a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 299a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonnamespace { 3003e8b6631e67e01e4960a7ba4668a50c596607473Chris Lattner class MemCpyOpt : public FunctionPass { 3012f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MemoryDependenceAnalysis *MD; 302a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool runOnFunction(Function &F); 303a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson public: 304a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson static char ID; // Pass identification, replacement for typeid 305081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson MemCpyOpt() : FunctionPass(ID) { 306081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson initializeMemCpyOptPass(*PassRegistry::getPassRegistry()); 3072f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD = 0; 308081c34b725980f995be9080eaec24cd3dfaaf065Owen Anderson } 309a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 310a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson private: 311a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // This transformation requires dominator postdominator info 312a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson virtual void getAnalysisUsage(AnalysisUsage &AU) const { 313a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.setPreservesCFG(); 314a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<DominatorTree>(); 315a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<MemoryDependenceAnalysis>(); 316a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addRequired<AliasAnalysis>(); 317a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<AliasAnalysis>(); 318a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AU.addPreserved<MemoryDependenceAnalysis>(); 319a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 320a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 321a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Helper fuctions 32261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool processStore(StoreInst *SI, BasicBlock::iterator &BBI); 32361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool processMemCpy(MemCpyInst *M); 324f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner bool processMemMove(MemMoveInst *M); 3256549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson bool performCallSlotOptzn(Instruction *cpy, Value *cpyDst, Value *cpySrc, 3266549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson uint64_t cpyLen, CallInst *C); 32743f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner bool processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep, 32843f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner uint64_t MSize); 3292f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner bool processByValArgument(CallSite CS, unsigned ArgNo); 330a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool iterateOnFunction(Function &F); 331a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 332a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 333a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson char MemCpyOpt::ID = 0; 334a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 335a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 336a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson// createMemCpyOptPass - The public interface to this file... 337a723d1e48f4a261512c28845c53eda569fa5218cOwen AndersonFunctionPass *llvm::createMemCpyOptPass() { return new MemCpyOpt(); } 338a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 3392ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_BEGIN(MemCpyOpt, "memcpyopt", "MemCpy Optimization", 3402ab36d350293c77fc8941ce1023e4899df7e3a82Owen Anderson false, false) 3412ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(DominatorTree) 3422ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_DEPENDENCY(MemoryDependenceAnalysis) 3432ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_AG_DEPENDENCY(AliasAnalysis) 3442ab36d350293c77fc8941ce1023e4899df7e3a82Owen AndersonINITIALIZE_PASS_END(MemCpyOpt, "memcpyopt", "MemCpy Optimization", 3452ab36d350293c77fc8941ce1023e4899df7e3a82Owen Anderson false, false) 346a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 347a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// processStore - When GVN is scanning forward over instructions, we look for 348a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// some other patterns to fold away. In particular, this looks for stores to 349a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// neighboring locations of memory. If it sees enough consequtive ones 350a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// (currently 4) it attempts to merge them together into a memcpy/memset. 35161c6ba85715fdcb66f746678879984151f1e5485Chris Lattnerbool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) { 352a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (SI->isVolatile()) return false; 353a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 3546549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson TargetData *TD = getAnalysisIfAvailable<TargetData>(); 3556549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (!TD) return false; 3566549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson 3576549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson // Detect cases where we're performing call slot forwarding, but 3586549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson // happen to be using a load-store pair to implement it, rather than 3596549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson // a memcpy. 3606549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (LoadInst *LI = dyn_cast<LoadInst>(SI->getOperand(0))) { 3616549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (!LI->isVolatile() && LI->hasOneUse()) { 3622f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MemDepResult dep = MD->getDependency(LI); 3636549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson CallInst *C = 0; 3646549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (dep.isClobber() && !isa<MemCpyInst>(dep.getInst())) 3656549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson C = dyn_cast<CallInst>(dep.getInst()); 3666549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson 3676549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (C) { 3686549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson bool changed = performCallSlotOptzn(LI, 3696549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson SI->getPointerOperand()->stripPointerCasts(), 3706549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson LI->getPointerOperand()->stripPointerCasts(), 3716549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson TD->getTypeStoreSize(SI->getOperand(0)->getType()), C); 3726549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (changed) { 3732f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD->removeInstruction(SI); 3746549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson SI->eraseFromParent(); 3756549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson LI->eraseFromParent(); 3766549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson ++NumMemCpyInstr; 3776549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson return true; 3786549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson } 3796549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson } 3806549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson } 3816549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson } 3826549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson 383ff1e98c72ae5f2aa805112925fd5c06049aa8e79Chris Lattner LLVMContext &Context = SI->getContext(); 384ff1e98c72ae5f2aa805112925fd5c06049aa8e79Chris Lattner 385a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // There are two cases that are interesting for this code to handle: memcpy 386a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // and memset. Right now we only handle memset. 387a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 388a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Ensure that the value being stored is something that can be memset'able a 389a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // byte at a time like "0" or "-1" or any width, as well as things like 390a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 0xA0A0A0A0 and 0.0. 391cf0fe8d813727383d630055bb9d1cde21b00b7e7Chris Lattner Value *ByteVal = isBytewiseValue(SI->getOperand(0)); 392a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!ByteVal) 393a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 394a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 395a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 396a195b7ffd6612a331751c7b6042d5cd921ee586cDan Gohman Module *M = SI->getParent()->getParent()->getParent(); 397a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 398a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Okay, so we now have a single store that can be splatable. Scan to find 399a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // all subsequent stores of the same value to offset from the same pointer. 400a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Join these together into ranges, so we can decide whether contiguous blocks 401a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // are stored. 4028942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman MemsetRanges Ranges(*TD); 403a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 404a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *StartPtr = SI->getPointerOperand(); 405a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 406a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator BI = SI; 407a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (++BI; !isa<TerminatorInst>(BI); ++BI) { 408a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) { 409a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the call is readnone, ignore it, otherwise bail out. We don't even 410a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // allow readonly here because we don't want something like: 411a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A). 412a292b2f49f1557f234e9fa987da690c6d24118e5Gabor Greif if (AA.getModRefBehavior(CallSite(BI)) == 413a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::DoesNotAccessMemory) 414a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 415a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 416a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // TODO: If this is a memset, try to join it in. 417a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 418a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 419a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (isa<VAArgInst>(BI) || isa<LoadInst>(BI)) 420a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 421a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 422a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a non-store instruction it is fine, ignore it. 423a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StoreInst *NextStore = dyn_cast<StoreInst>(BI); 424a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore == 0) continue; 425a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 426a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If this is a store, see if we can merge it in. 427a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (NextStore->isVolatile()) break; 428a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 429a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this stored value is of the same byte-splattable value. 430cf0fe8d813727383d630055bb9d1cde21b00b7e7Chris Lattner if (ByteVal != isBytewiseValue(NextStore->getOperand(0))) 431a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 432a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 433a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check to see if this store is to a constant offset from the start ptr. 434a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson int64_t Offset; 4358942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, *TD)) 436a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson break; 437a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 438a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(Offset, NextStore); 439a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 440a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 441a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we have no ranges, then we just had a single store with nothing that 442a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // could be merged in. This is a very common case of course. 443a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Ranges.empty()) 444a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 445a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 446a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If we had at least one store that could be merged in, add the starting 447a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // store as well. We try to avoid this unless there is at least something 448a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // interesting as a small compile-time optimization. 449a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Ranges.addStore(0, SI); 450a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 451a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 452a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Now that we have full information about ranges, loop over the ranges and 453a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // emit memset's for anything big enough to be worthwhile. 454a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson bool MadeChange = false; 455a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end(); 456a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) { 457a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson const MemsetRange &Range = *I; 458a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 459a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (Range.TheStores.size() == 1) continue; 460a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 461a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If it is profitable to lower this range to memset, do so now. 4628942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!Range.isProfitableToUseMemset(*TD)) 463a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson continue; 464a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 465a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Otherwise, we do want to transform this! Create a new memset. We put 466a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memset right before the first instruction that isn't part of this 467a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memset block. This ensure that the memset is dominated by any addressing 468a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // instruction needed by the start of the block. 469a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson BasicBlock::iterator InsertPt = BI; 47020adc9dc4650313f017b27d9818eb2176238113dMon P Wang 471a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Get the starting pointer of the block. 472a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr = Range.StartPtr; 47320adc9dc4650313f017b27d9818eb2176238113dMon P Wang 47420adc9dc4650313f017b27d9818eb2176238113dMon P Wang // Determine alignment 47520adc9dc4650313f017b27d9818eb2176238113dMon P Wang unsigned Alignment = Range.Alignment; 47620adc9dc4650313f017b27d9818eb2176238113dMon P Wang if (Alignment == 0) { 47720adc9dc4650313f017b27d9818eb2176238113dMon P Wang const Type *EltType = 47820adc9dc4650313f017b27d9818eb2176238113dMon P Wang cast<PointerType>(StartPtr->getType())->getElementType(); 47920adc9dc4650313f017b27d9818eb2176238113dMon P Wang Alignment = TD->getABITypeAlignment(EltType); 48020adc9dc4650313f017b27d9818eb2176238113dMon P Wang } 48120adc9dc4650313f017b27d9818eb2176238113dMon P Wang 482a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Cast the start ptr to be i8* as memset requires. 48320adc9dc4650313f017b27d9818eb2176238113dMon P Wang const PointerType* StartPTy = cast<PointerType>(StartPtr->getType()); 48420adc9dc4650313f017b27d9818eb2176238113dMon P Wang const PointerType *i8Ptr = Type::getInt8PtrTy(Context, 48520adc9dc4650313f017b27d9818eb2176238113dMon P Wang StartPTy->getAddressSpace()); 48620adc9dc4650313f017b27d9818eb2176238113dMon P Wang if (StartPTy!= i8Ptr) 487460f656475738d1a95a6be95346908ce1597df25Daniel Dunbar StartPtr = new BitCastInst(StartPtr, i8Ptr, StartPtr->getName(), 488a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson InsertPt); 48920adc9dc4650313f017b27d9818eb2176238113dMon P Wang 490a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson Value *Ops[] = { 491a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson StartPtr, ByteVal, // Start, value 492e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson // size 493ff1e98c72ae5f2aa805112925fd5c06049aa8e79Chris Lattner ConstantInt::get(Type::getInt64Ty(Context), Range.End-Range.Start), 494e922c0201916e0b980ab3cfe91e1413e68d55647Owen Anderson // align 49520adc9dc4650313f017b27d9818eb2176238113dMon P Wang ConstantInt::get(Type::getInt32Ty(Context), Alignment), 49620adc9dc4650313f017b27d9818eb2176238113dMon P Wang // volatile 497f601d6df6f43bb833461cbcee475c36998e6c259Benjamin Kramer ConstantInt::getFalse(Context), 498a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson }; 49920adc9dc4650313f017b27d9818eb2176238113dMon P Wang const Type *Tys[] = { Ops[0]->getType(), Ops[2]->getType() }; 50020adc9dc4650313f017b27d9818eb2176238113dMon P Wang 50120adc9dc4650313f017b27d9818eb2176238113dMon P Wang Function *MemSetF = Intrinsic::getDeclaration(M, Intrinsic::memset, Tys, 2); 50220adc9dc4650313f017b27d9818eb2176238113dMon P Wang 50320adc9dc4650313f017b27d9818eb2176238113dMon P Wang Value *C = CallInst::Create(MemSetF, Ops, Ops+5, "", InsertPt); 504cb33fd17cce475a1d47b2695e311b6934ad0ef86David Greene DEBUG(dbgs() << "Replace stores:\n"; 505a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i) 5062f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner dbgs() << *Range.TheStores[i] << '\n'; 5072f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner dbgs() << "With: " << *C << '\n'); C=C; 508a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 509a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson // Don't invalidate the iterator 510a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson BBI = BI; 511a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson 512a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Zap all the stores. 513ff1e98c72ae5f2aa805112925fd5c06049aa8e79Chris Lattner for (SmallVector<StoreInst*, 16>::const_iterator 514ff1e98c72ae5f2aa805112925fd5c06049aa8e79Chris Lattner SI = Range.TheStores.begin(), 515a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson SE = Range.TheStores.end(); SI != SE; ++SI) 516a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson (*SI)->eraseFromParent(); 517a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson ++NumMemSetInfer; 518a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson MadeChange = true; 519a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 520a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 521a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return MadeChange; 522a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 523a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 524a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 525a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// performCallSlotOptzn - takes a memcpy and a call that it depends on, 526a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// and checks for the possibility of a call slot optimization by having 527a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson/// the call write its result directly into the destination of the memcpy. 5286549121c660dfd18361cd3daf6c766bee80d3097Owen Andersonbool MemCpyOpt::performCallSlotOptzn(Instruction *cpy, 5296549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson Value *cpyDest, Value *cpySrc, 5306549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson uint64_t cpyLen, CallInst *C) { 531a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The general transformation to keep in mind is 532a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 533a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., src, ...) 534a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 535a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 536a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // -> 537a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 538a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy(dest, src, ...) 539a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // call @func(..., dest, ...) 540a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // 541a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since moving the memcpy is technically awkward, we additionally check that 542a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // src only holds uninitialized values at the moment of the call, meaning that 543a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy can be discarded rather than moved. 544a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 545a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Deliberately get the source and destination with bitcasts stripped away, 546a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // because we'll need to do type comparisons based on the underlying type. 5477d3056b16038a6a09c452c0dfcc3c8f4e421506aGabor Greif CallSite CS(C); 548a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 549a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Require that src be an alloca. This simplifies the reasoning considerably. 55061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner AllocaInst *srcAlloca = dyn_cast<AllocaInst>(cpySrc); 551a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcAlloca) 552a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 553a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 554a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that all of src is copied to dest. 55561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner TargetData *TD = getAnalysisIfAvailable<TargetData>(); 5568942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman if (!TD) return false; 557a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 55861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize()); 559a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!srcArraySize) 560a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 561a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 5628942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman uint64_t srcSize = TD->getTypeAllocSize(srcAlloca->getAllocatedType()) * 563a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcArraySize->getZExtValue(); 564a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 5656549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (cpyLen < srcSize) 566a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 567a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 568a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that accessing the first srcSize bytes of dest will not cause a 569a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // trap. Otherwise the transform is invalid since it might cause a trap 570a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // to occur earlier than it otherwise would. 57161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (AllocaInst *A = dyn_cast<AllocaInst>(cpyDest)) { 572a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // The destination is an alloca. Check it is larger than srcSize. 57361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *destArraySize = dyn_cast<ConstantInt>(A->getArraySize()); 574a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!destArraySize) 575a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 576a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 5778942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman uint64_t destSize = TD->getTypeAllocSize(A->getAllocatedType()) * 578a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson destArraySize->getZExtValue(); 579a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 580a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 581a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 58261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner } else if (Argument *A = dyn_cast<Argument>(cpyDest)) { 583a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // If the destination is an sret parameter then only accesses that are 584a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // outside of the returned struct type can trap. 585a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!A->hasStructRetAttr()) 586a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 587a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 58861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner const Type *StructTy = cast<PointerType>(A->getType())->getElementType(); 5898942f9bb9f8bfb0d113db6d4a1ae7203dcf4510aDan Gohman uint64_t destSize = TD->getTypeAllocSize(StructTy); 590a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 591a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (destSize < srcSize) 592a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 593a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else { 594a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 595a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 596a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 597a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Check that src is not accessed except via the call and the memcpy. This 598a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // guarantees that it holds only undefined values when passed in (so the final 599a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // memcpy can be dropped), that it is not read or written between the call and 600a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the memcpy, and that writing beyond the end of it is undefined. 601a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(), 602a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcAlloca->use_end()); 603a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson while (!srcUseList.empty()) { 604321a813c536e2f1f2f05bbe78a7fbf64046f0557Dan Gohman User *UI = srcUseList.pop_back_val(); 605a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 606009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (isa<BitCastInst>(UI)) { 607a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 608a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson I != E; ++I) 609a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson srcUseList.push_back(*I); 61061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner } else if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(UI)) { 611009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (G->hasAllZeroIndices()) 612009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); 613009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson I != E; ++I) 614009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson srcUseList.push_back(*I); 615009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson else 616009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson return false; 617a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } else if (UI != C && UI != cpy) { 618a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 619a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 620a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 621a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 622a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Since we're changing the parameter to the callsite, we need to make sure 623a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // that what would be the new parameter dominates the callsite. 62461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner DominatorTree &DT = getAnalysis<DominatorTree>(); 62561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (Instruction *cpyDestInst = dyn_cast<Instruction>(cpyDest)) 626a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (!DT.dominates(cpyDestInst, C)) 627a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 628a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 629a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // In addition to knowing that the call does not access src in some 630a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // unexpected manner, for example via a global, which we deduce from 631a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // the use analysis, we also need to know that it does not sneakily 632a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // access dest. We rely on AA to figure this out for us. 63361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 6346549121c660dfd18361cd3daf6c766bee80d3097Owen Anderson if (AA.getModRefInfo(C, cpyDest, srcSize) != 635a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson AliasAnalysis::NoModRef) 636a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 637a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 638a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // All the checks have passed, so do the transformation. 63912cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson bool changedArgument = false; 640a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson for (unsigned i = 0; i < CS.arg_size(); ++i) 641009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson if (CS.getArgument(i)->stripPointerCasts() == cpySrc) { 642a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson if (cpySrc->getType() != cpyDest->getType()) 6437cbd8a3e92221437048b484d5ef9c0a22d0f8c58Gabor Greif cpyDest = CastInst::CreatePointerCast(cpyDest, cpySrc->getType(), 644a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson cpyDest->getName(), C); 64512cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson changedArgument = true; 64661c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (CS.getArgument(i)->getType() == cpyDest->getType()) 647009e4f760969e3530cc2641a9599e646a20580c2Owen Anderson CS.setArgument(i, cpyDest); 64861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner else 64961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner CS.setArgument(i, CastInst::CreatePointerCast(cpyDest, 65061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner CS.getArgument(i)->getType(), cpyDest->getName(), C)); 651a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 652a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 65312cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson if (!changedArgument) 65412cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson return false; 65512cb36c11564e2a7cf85b4b29bddab5c5fd63cf5Owen Anderson 656a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Drop any cached information about the call, because we may have changed 657a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // its dependence information by changing its parameter. 6582f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD->removeInstruction(C); 659a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 6602f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // Remove the memcpy. 6612f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD->removeInstruction(cpy); 662fe60104ac97f3a8736dcfbfdf9547c7b7cc7b951Dan Gohman ++NumMemCpyInstr; 663a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 664a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return true; 665a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 666a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 66743f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// processMemCpyMemCpyDependence - We've found that the (upward scanning) 66843f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// memory dependence of memcpy 'M' is the memcpy 'MDep'. Try to simplify M to 66943f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// copy from MDep's input if we can. MSize is the size of M's copy. 67043f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// 67143f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattnerbool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep, 67243f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner uint64_t MSize) { 673a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // We can only transforms memcpy's where the dest of one is the source of the 67443f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner // other. 6752f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (M->getSource() != MDep->getDest() || MDep->isVolatile()) 676a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 677a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 678f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner // If dep instruction is reading from our current input, then it is a noop 679f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner // transfer and substituting the input won't change this instruction. Just 680f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner // ignore the input and let someone else zap MDep. This handles cases like: 681f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner // memcpy(a <- a) 682f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner // memcpy(b <- a) 683f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner if (M->getSource() == MDep->getSource()) 684f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner return false; 685f7f35467a9aac818bd5813c17e80d7efb66dadd7Chris Lattner 686a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // Second, the length of the memcpy's must be the same, or the preceeding one 687a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson // must be larger than the following one. 68861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner ConstantInt *C1 = dyn_cast<ConstantInt>(MDep->getLength()); 68943f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner if (!C1) return false; 690a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 691a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson uint64_t DepSize = C1->getValue().getZExtValue(); 69243f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner if (DepSize < MSize) 693a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson return false; 694a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 6952f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 696604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner 697604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // Verify that the copied-from memory doesn't change in between the two 698604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // transfers. For example, in: 699604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // memcpy(a <- b) 700604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // *b = 42; 701604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // memcpy(c <- a) 702604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // It would be invalid to transform the second memcpy into memcpy(c <- b). 703604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // 704604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // TODO: If the code between M and MDep is transparent to the destination "c", 705604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // then we could still perform the xform by moving M up to the first memcpy. 706604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // 707604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // NOTE: This is conservative, it will stop on any read from the source loc, 708604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // not just the defining memcpy. 709604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner MemDepResult SourceDep = 710604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner MD->getPointerDependencyFrom(AA.getLocationForSource(MDep), 711604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner false, M, M->getParent()); 712604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner if (!SourceDep.isClobber() || SourceDep.getInst() != MDep) 713604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner return false; 7145a7aeaa01904b9b0adf256108f302f8961295754Chris Lattner 7155a7aeaa01904b9b0adf256108f302f8961295754Chris Lattner // If the dest of the second might alias the source of the first, then the 7165a7aeaa01904b9b0adf256108f302f8961295754Chris Lattner // source and dest might overlap. We still want to eliminate the intermediate 7175a7aeaa01904b9b0adf256108f302f8961295754Chris Lattner // value, but we have to generate a memmove instead of memcpy. 7182f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner Intrinsic::ID ResultFn = Intrinsic::memcpy; 71912f7085027657957e08aea597b5c9fed44052969Chris Lattner if (!AA.isNoAlias(M->getRawDest(), MSize, MDep->getRawSource(), DepSize)) 7205a7aeaa01904b9b0adf256108f302f8961295754Chris Lattner ResultFn = Intrinsic::memmove; 721a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 7222f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // If all checks passed, then we can transform M. 723245b7f6ec26a8d27c984da4cceb7cfc27abcba6bChris Lattner const Type *ArgTys[3] = { 724245b7f6ec26a8d27c984da4cceb7cfc27abcba6bChris Lattner M->getRawDest()->getType(), 72543f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner MDep->getRawSource()->getType(), 726245b7f6ec26a8d27c984da4cceb7cfc27abcba6bChris Lattner M->getLength()->getType() 727245b7f6ec26a8d27c984da4cceb7cfc27abcba6bChris Lattner }; 72843f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner Function *MemCpyFun = 7292f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner Intrinsic::getDeclaration(MDep->getParent()->getParent()->getParent(), 7305a7aeaa01904b9b0adf256108f302f8961295754Chris Lattner ResultFn, ArgTys, 3); 73143f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner 73204fcbf954fef6d9866b5120f406e7401dc9aa29fEric Christopher // Make sure to use the lesser of the alignment of the source and the dest 73304fcbf954fef6d9866b5120f406e7401dc9aa29fEric Christopher // since we're changing where we're reading from, but don't want to increase 73404fcbf954fef6d9866b5120f406e7401dc9aa29fEric Christopher // the alignment past what can be read from or written to. 735c69a00047013a0e2e07ae44c38e013a7d905b10eEric Christopher // TODO: Is this worth it if we're creating a less aligned memcpy? For 736c69a00047013a0e2e07ae44c38e013a7d905b10eEric Christopher // example we could be moving from movaps -> movq on x86. 737d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner unsigned Align = std::min(MDep->getAlignment(), M->getAlignment()); 73820adc9dc4650313f017b27d9818eb2176238113dMon P Wang Value *Args[5] = { 739d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner M->getRawDest(), 740d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner MDep->getRawSource(), 741d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner M->getLength(), 7422f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner ConstantInt::get(Type::getInt32Ty(MemCpyFun->getContext()), Align), 743d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner M->getVolatileCst() 744dfe964ce8c367248e587f2d9ecc7fac5ee2c6fdcChris Lattner }; 745604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner CallInst::Create(MemCpyFun, Args, Args+5, "", M); 746d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner 747604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // Remove the instruction we're replacing. 7482f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD->removeInstruction(M); 749d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner M->eraseFromParent(); 750d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner ++NumMemCpyInstr; 751d528be6636539567194981a8c0f8b90220bec0a5Chris Lattner return true; 752a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 753a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 75443f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner 75543f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// processMemCpy - perform simplification of memcpy's. If we have memcpy A 75643f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// which copies X to Y, and memcpy B which copies Y to Z, then we can rewrite 75743f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// B to be a memcpy from X to Z (or potentially a memmove, depending on 75843f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// circumstances). This allows later passes to remove the first memcpy 75943f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner/// altogether. 76043f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattnerbool MemCpyOpt::processMemCpy(MemCpyInst *M) { 7612f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // We can only optimize statically-sized memcpy's that are non-volatile. 7622f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner ConstantInt *CopySize = dyn_cast<ConstantInt>(M->getLength()); 7632f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (CopySize == 0 || M->isVolatile()) return false; 76443f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner 7658fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner // If the source and destination of the memcpy are the same, then zap it. 7668fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner if (M->getSource() == M->getDest()) { 7678fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner MD->removeInstruction(M); 7688fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner M->eraseFromParent(); 7698fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner return false; 7708fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner } 7718fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner 7728fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner 77343f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner // The are two possible optimizations we can do for memcpy: 77443f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner // a) memcpy-memcpy xform which exposes redundance for DSE. 77543f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner // b) call-memcpy xform for return slot optimization. 7762f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MemDepResult DepInfo = MD->getDependency(M); 7772f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (!DepInfo.isClobber()) 77843f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner return false; 77943f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner 7802f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(DepInfo.getInst())) 7812f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner return processMemCpyMemCpyDependence(M, MDep, CopySize->getZExtValue()); 78243f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner 7832f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) { 7848fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner if (performCallSlotOptzn(M, M->getDest(), M->getSource(), 7858fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner CopySize->getZExtValue(), C)) { 7868fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner M->eraseFromParent(); 7878fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner return true; 7888fdca6a8738c1ad7091137688ee48c9e623b75bbChris Lattner } 78943f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner } 79043f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner return false; 79143f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner} 79243f8e43eb2a166f50c3a077040d8bdb24104433aChris Lattner 793f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner/// processMemMove - Transforms memmove calls to memcpy calls when the src/dst 794f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner/// are guaranteed not to alias. 795f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattnerbool MemCpyOpt::processMemMove(MemMoveInst *M) { 796f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); 797f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 798f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // If the memmove is a constant size, use it for the alias query, this allows 799f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // us to optimize things like: memmove(P, P+64, 64); 8003da848bbda62b25c12335998aaa44ab361f0bf15Dan Gohman uint64_t MemMoveSize = AliasAnalysis::UnknownSize; 801f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner if (ConstantInt *Len = dyn_cast<ConstantInt>(M->getLength())) 802f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner MemMoveSize = Len->getZExtValue(); 803f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 804f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // See if the pointers alias. 805f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner if (AA.alias(M->getRawDest(), MemMoveSize, M->getRawSource(), MemMoveSize) != 806f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner AliasAnalysis::NoAlias) 807f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner return false; 808f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 809cb33fd17cce475a1d47b2695e311b6934ad0ef86David Greene DEBUG(dbgs() << "MemCpyOpt: Optimizing memmove -> memcpy: " << *M << "\n"); 810f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 811f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // If not, then we know we can transform this. 812f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner Module *Mod = M->getParent()->getParent()->getParent(); 81320adc9dc4650313f017b27d9818eb2176238113dMon P Wang const Type *ArgTys[3] = { M->getRawDest()->getType(), 81420adc9dc4650313f017b27d9818eb2176238113dMon P Wang M->getRawSource()->getType(), 81520adc9dc4650313f017b27d9818eb2176238113dMon P Wang M->getLength()->getType() }; 816a399781289092fcdceb58b21174229f4373c4191Gabor Greif M->setCalledFunction(Intrinsic::getDeclaration(Mod, Intrinsic::memcpy, 817a399781289092fcdceb58b21174229f4373c4191Gabor Greif ArgTys, 3)); 81805cd03b33559732f8ed55e5ff7554fd06d59eb6aDuncan Sands 819f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // MemDep may have over conservative information about this instruction, just 820f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner // conservatively flush it from the cache. 8212f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD->removeInstruction(M); 82205cd03b33559732f8ed55e5ff7554fd06d59eb6aDuncan Sands 82305cd03b33559732f8ed55e5ff7554fd06d59eb6aDuncan Sands ++NumMoveToCpy; 824f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner return true; 825f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner} 826f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 8272f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner/// processByValArgument - This is called on every byval argument in call sites. 8282f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattnerbool MemCpyOpt::processByValArgument(CallSite CS, unsigned ArgNo) { 8292f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner TargetData *TD = getAnalysisIfAvailable<TargetData>(); 8302f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (!TD) return false; 831f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner 832604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // Find out what feeds this byval argument. 8332f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner Value *ByValArg = CS.getArgument(ArgNo); 834b5a3196f809e8edb2e9fef09de1de3d382cb852fChris Lattner const Type *ByValTy =cast<PointerType>(ByValArg->getType())->getElementType(); 835b5a3196f809e8edb2e9fef09de1de3d382cb852fChris Lattner uint64_t ByValSize = TD->getTypeAllocSize(ByValTy); 836604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner MemDepResult DepInfo = 837604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner MD->getPointerDependencyFrom(AliasAnalysis::Location(ByValArg, ByValSize), 838604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner true, CS.getInstruction(), 839604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner CS.getInstruction()->getParent()); 8402f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (!DepInfo.isClobber()) 8412f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner return false; 8422f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 8432f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // If the byval argument isn't fed by a memcpy, ignore it. If it is fed by 8442f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // a memcpy, see if we can byval from the source of the memcpy instead of the 8452f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // result. 8462f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MemCpyInst *MDep = dyn_cast<MemCpyInst>(DepInfo.getInst()); 8472f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (MDep == 0 || MDep->isVolatile() || 8482f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner ByValArg->stripPointerCasts() != MDep->getDest()) 8492f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner return false; 8502f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 8512f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // The length of the memcpy must be larger or equal to the size of the byval. 8522f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner ConstantInt *C1 = dyn_cast<ConstantInt>(MDep->getLength()); 853604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner if (C1 == 0 || C1->getValue().getZExtValue() < ByValSize) 8542f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner return false; 8552f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 8562f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // Get the alignment of the byval. If it is greater than the memcpy, then we 8572f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // can't do the substitution. If the call doesn't specify the alignment, then 8582f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // it is some target specific value that we can't know. 8592f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner unsigned ByValAlign = CS.getParamAlignment(ArgNo+1); 8602f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (ByValAlign == 0 || MDep->getAlignment() < ByValAlign) 8612f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner return false; 8622f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 8632f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // Verify that the copied-from memory doesn't change in between the memcpy and 8642f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // the byval call. 8652f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // memcpy(a <- b) 8662f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // *b = 42; 8672f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // foo(*a) 8682f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // It would be invalid to transform the second memcpy into foo(*b). 869604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // 870604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // NOTE: This is conservative, it will stop on any read from the source loc, 871604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner // not just the defining memcpy. 872604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner MemDepResult SourceDep = 873604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner MD->getPointerDependencyFrom(AliasAnalysis::getLocationForSource(MDep), 874604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner false, CS.getInstruction(), MDep->getParent()); 875604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner if (!SourceDep.isClobber() || SourceDep.getInst() != MDep) 876604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner return false; 877604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner 8782f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner Value *TmpCast = MDep->getSource(); 8792f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (MDep->getSource()->getType() != ByValArg->getType()) 8802f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner TmpCast = new BitCastInst(MDep->getSource(), ByValArg->getType(), 8812f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner "tmpcast", CS.getInstruction()); 882604f6fe553eb430c6d991f72baa3633842759b49Chris Lattner 8832f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner DEBUG(dbgs() << "MemCpyOpt: Forwarding memcpy to byval:\n" 8842f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner << " " << *MDep << "\n" 8852f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner << " " << *CS.getInstruction() << "\n"); 8862f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 8872f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // Otherwise we're good! Update the byval argument. 8882f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner CS.setArgument(ArgNo, TmpCast); 8892f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner ++NumMemCpyInstr; 8902f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner return true; 8912f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner} 8922f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 8932f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner/// iterateOnFunction - Executes one iteration of MemCpyOpt. 894a723d1e48f4a261512c28845c53eda569fa5218cOwen Andersonbool MemCpyOpt::iterateOnFunction(Function &F) { 89561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool MadeChange = false; 896a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 89761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner // Walk all instruction in the function. 898a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) { 8992f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) { 90061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner // Avoid invalidating the iterator. 90161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner Instruction *I = BI++; 902a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 9032f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner bool RepeatInstruction = false; 9042f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 905a8bd65835be9e1ce07f5006e92625ec4e9fa387aOwen Anderson if (StoreInst *SI = dyn_cast<StoreInst>(I)) 90661c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MadeChange |= processStore(SI, BI); 9072f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner else if (MemCpyInst *M = dyn_cast<MemCpyInst>(I)) { 9082f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner RepeatInstruction = processMemCpy(M); 9092f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner } else if (MemMoveInst *M = dyn_cast<MemMoveInst>(I)) { 9102f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner RepeatInstruction = processMemMove(M); 9112f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner } else if (CallSite CS = (Value*)I) { 9122f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner for (unsigned i = 0, e = CS.arg_size(); i != e; ++i) 9132f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (CS.paramHasAttr(i+1, Attribute::ByVal)) 9142f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MadeChange |= processByValArgument(CS, i); 9152f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner } 9162f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner 9172f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner // Reprocess the instruction if desired. 9182f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner if (RepeatInstruction) { 9192f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner --BI; 9202f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MadeChange = true; 921f41eaacee4a4a2d4339dd553626d98c73650c8c7Chris Lattner } 922a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 923a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson } 924a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson 92561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner return MadeChange; 926a723d1e48f4a261512c28845c53eda569fa5218cOwen Anderson} 92761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 92861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// MemCpyOpt::runOnFunction - This is the main transformation entry point for a 92961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// function. 93061c6ba85715fdcb66f746678879984151f1e5485Chris Lattner// 93161c6ba85715fdcb66f746678879984151f1e5485Chris Lattnerbool MemCpyOpt::runOnFunction(Function &F) { 93261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner bool MadeChange = false; 9332f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD = &getAnalysis<MemoryDependenceAnalysis>(); 93461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner while (1) { 93561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner if (!iterateOnFunction(F)) 93661c6ba85715fdcb66f746678879984151f1e5485Chris Lattner break; 93761c6ba85715fdcb66f746678879984151f1e5485Chris Lattner MadeChange = true; 93861c6ba85715fdcb66f746678879984151f1e5485Chris Lattner } 93961c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 9402f5f90ad3e9b00cf21ae8e3f55b93f0be1d504c3Chris Lattner MD = 0; 94161c6ba85715fdcb66f746678879984151f1e5485Chris Lattner return MadeChange; 94261c6ba85715fdcb66f746678879984151f1e5485Chris Lattner} 94361c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 94461c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 94561c6ba85715fdcb66f746678879984151f1e5485Chris Lattner 946