Loads.h revision 210299
1//===- Loads.h - Local load analysis --------------------------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file declares simple local analyses for load instructions. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_ANALYSIS_LOADS_H 15#define LLVM_ANALYSIS_LOADS_H 16 17#include "llvm/BasicBlock.h" 18 19namespace llvm { 20 21class AliasAnalysis; 22class TargetData; 23 24/// isSafeToLoadUnconditionally - Return true if we know that executing a load 25/// from this value cannot trap. If it is not obviously safe to load from the 26/// specified pointer, we do a quick local scan of the basic block containing 27/// ScanFrom, to determine if the address is already accessed. 28bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom, 29 unsigned Align, const TargetData *TD = 0); 30 31/// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at 32/// the instruction before ScanFrom) checking to see if we have the value at 33/// the memory address *Ptr locally available within a small number of 34/// instructions. If the value is available, return it. 35/// 36/// If not, return the iterator for the last validated instruction that the 37/// value would be live through. If we scanned the entire block and didn't 38/// find something that invalidates *Ptr or provides it, ScanFrom would be 39/// left at begin() and this returns null. ScanFrom could also be left 40/// 41/// MaxInstsToScan specifies the maximum instructions to scan in the block. 42/// If it is set to 0, it will scan the whole block. You can also optionally 43/// specify an alias analysis implementation, which makes this more precise. 44Value *FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, 45 BasicBlock::iterator &ScanFrom, 46 unsigned MaxInstsToScan = 6, 47 AliasAnalysis *AA = 0); 48 49} 50 51#endif 52